[PATCH -mm 00/25] get_user_pages() for dax pte and pmd mappings

[PATCH -mm 00/25] get_user_pages() for dax pte and pmd mappings

[Dan Williams]

Andrew, please pull dax-gup support into -mm.

This series, based on next-20151203, has been out for review in one form
or another since September [1].  The concept was reviewed at Kernel
Summit in the "ZONE_DEVICE" tech-topic presentation.  Since the RFC
posting [2] it has received fixes and is now passing the unit tests from
ndctl [3] and nvml [4].

Logan Gunthorpe has also offered up functional testing of his use case
for devm_memremap_pages() [5] (a "Tested-by" for the latest revision is
still pending).

[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002199.html
[2]: https://lists.01.org/pipermail/linux-nvdimm/2015-November/003033.html
[3]: https://github.com/pmem/ndctl
[4]: https://github.com/pmem/nvml
[5]: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002576.html

A git tree of this set is available here:

  git://git.kernel.org/pub/scm/linux/kernel/git/djbw/nvdimm libnvdimm-pending

The libnvdimm-pending branch has received a build success notification
from the kbuild-test-robot over 105 configs.

---

Summary:

To date, we have implemented two I/O usage models for persistent memory,
PMEM (a persistent "ram disk") and DAX (mmap persistent memory into
userspace).  This series adds a third, DAX-GUP, that allows DAX mappings
to be the target of direct-i/o.  It allows userspace to coordinate
DMA/RDMA from/to persistent memory.

The implementation leverages the ZONE_DEVICE mm-zone that went into
4.3-rc1 (also discussed at kernel summit) to flag pages that are owned
and dynamically mapped by a device driver.  The pmem driver, after
mapping a persistent memory range into the system memmap via
devm_memremap_pages(), arranges for DAX to distinguish pfn-only versus
page-backed pmem-pfns via flags in the new pfn_t type.

The DAX code, upon seeing a PFN_DEV+PFN_MAP flagged pfn, flags the
resulting pte(s) inserted into the process page tables with a new
_PAGE_DEVMAP flag.  Later, when get_user_pages() is walking ptes it keys
off _PAGE_DEVMAP to pin the device hosting the page range active.
Finally, get_page() and put_page() are modified to take references
against the device driver established page mapping.

Finally, this need for "struct page" for persistent memory requires
memory capacity to store the memmap array.  Given the memmap array for a
large pool of persistent may exhaust available DRAM introduce a
mechanism to allocate the memmap from persistent memory.  The new "struct
vmem_altmap *"  parameter to devm_memremap_pages() enables
arch_add_memory() to use reserved pmem capacity rather than the page
allocator.

---

Dan Williams (23):
      pmem, dax: clean up clear_pmem()
      dax: increase granularity of dax_clear_blocks() operations
      dax: guarantee page aligned results from bdev_direct_access()
      dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
      um: kill pfn_t
      kvm: rename pfn_t to kvm_pfn_t
      mm, dax, pmem: introduce pfn_t
      mm: introduce find_dev_pagemap()
      x86, mm: introduce vmem_altmap to augment vmemmap_populate()
      libnvdimm, pfn, pmem: allocate memmap array in persistent memory
      avr32: convert to asm-generic/memory_model.h
      hugetlb: fix compile error on tile
      frv: fix compiler warning from definition of __pmd()
      x86, mm: introduce _PAGE_DEVMAP
      mm, dax, gpu: convert vm_insert_mixed to pfn_t
      mm, dax: convert vmf_insert_pfn_pmd() to pfn_t
      list: introduce list_del_poison()
      libnvdimm, pmem: move request_queue allocation earlier in probe
      mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup
      mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd
      mm, x86: get_user_pages() for dax mappings
      dax: provide diagnostics for pmd mapping failures
      dax: re-enable dax pmd mappings

Ross Zwisler (1):
      mm, dax: fix livelock, allow dax pmd mappings to become writeable

Toshi Kani (1):
      dax: Split pmd map when fallback on COW


 arch/alpha/include/asm/pgtable.h        |    1 
 arch/arm/include/asm/kvm_mmu.h          |    5 -
 arch/arm/kvm/mmu.c                      |   10 +
 arch/arm64/include/asm/kvm_mmu.h        |    3 
 arch/avr32/include/asm/page.h           |    8 -
 arch/frv/include/asm/page.h             |    2 
 arch/ia64/include/asm/page.h            |    1 
 arch/ia64/include/asm/pgtable.h         |    1 
 arch/m68k/include/asm/page_mm.h         |    1 
 arch/m68k/include/asm/page_no.h         |    1 
 arch/mips/include/asm/kvm_host.h        |    6 -
 arch/mips/kvm/emulate.c                 |    2 
 arch/mips/kvm/tlb.c                     |   14 +
 arch/mn10300/include/asm/page.h         |    1 
 arch/parisc/include/asm/pgtable.h       |    1 
 arch/powerpc/include/asm/kvm_book3s.h   |    4 
 arch/powerpc/include/asm/kvm_ppc.h      |    2 
 arch/powerpc/include/asm/pgtable.h      |    1 
 arch/powerpc/kvm/book3s.c               |    6 -
 arch/powerpc/kvm/book3s_32_mmu_host.c   |    2 
 arch/powerpc/kvm/book3s_64_mmu_host.c   |    2 
 arch/powerpc/kvm/e500.h                 |    2 
 arch/powerpc/kvm/e500_mmu_host.c        |    8 -
 arch/powerpc/kvm/trace_pr.h             |    2 
 arch/powerpc/sysdev/axonram.c           |    8 -
 arch/sh/include/asm/pgtable-3level.h    |    1 
 arch/sparc/include/asm/pgtable_64.h     |    2 
 arch/tile/include/asm/pgtable.h         |    1 
 arch/um/include/asm/page.h              |    7 -
 arch/um/include/asm/pgtable-3level.h    |    5 -
 arch/um/include/asm/pgtable.h           |    2 
 arch/x86/include/asm/page_types.h       |    3 
 arch/x86/include/asm/pgtable.h          |   26 +++
 arch/x86/include/asm/pgtable_types.h    |    7 +
 arch/x86/include/asm/pmem.h             |    7 -
 arch/x86/kvm/iommu.c                    |   11 +
 arch/x86/kvm/mmu.c                      |   37 ++--
 arch/x86/kvm/mmu_audit.c                |    2 
 arch/x86/kvm/paging_tmpl.h              |    6 -
 arch/x86/kvm/vmx.c                      |    2 
 arch/x86/kvm/x86.c                      |    2 
 arch/x86/mm/gup.c                       |   56 +++++-
 arch/x86/mm/init_64.c                   |   32 +++
 arch/x86/mm/pat.c                       |    4 
 drivers/block/brd.c                     |    4 
 drivers/gpu/drm/exynos/exynos_drm_gem.c |    3 
 drivers/gpu/drm/gma500/framebuffer.c    |    3 
 drivers/gpu/drm/msm/msm_gem.c           |    3 
 drivers/gpu/drm/omapdrm/omap_gem.c      |    6 -
 drivers/gpu/drm/ttm/ttm_bo_vm.c         |    3 
 drivers/nvdimm/pfn_devs.c               |    3 
 drivers/nvdimm/pmem.c                   |   70 +++++--
 drivers/s390/block/dcssblk.c            |   10 -
 fs/Kconfig                              |    3 
 fs/block_dev.c                          |   15 +-
 fs/dax.c                                |  290 +++++++++++++++++++----------
 include/asm-generic/pgtable.h           |   10 +
 include/linux/blkdev.h                  |   19 ++
 include/linux/huge_mm.h                 |   15 +-
 include/linux/hugetlb.h                 |    1 
 include/linux/io.h                      |   15 --
 include/linux/kvm_host.h                |   37 ++--
 include/linux/kvm_types.h               |    2 
 include/linux/list.h                    |   17 ++
 include/linux/memory_hotplug.h          |    3 
 include/linux/mm.h                      |  310 ++++++++++++++++++++++++++++++-
 include/linux/mm_types.h                |    5 +
 include/linux/pfn.h                     |    9 +
 kernel/memremap.c                       |  188 ++++++++++++++++++-
 lib/list_debug.c                        |    4 
 mm/gup.c                                |   18 ++
 mm/huge_memory.c                        |  131 +++++++++----
 mm/memory.c                             |   25 +--
 mm/memory_hotplug.c                     |   66 +++++--
 mm/mprotect.c                           |    5 -
 mm/page_alloc.c                         |   10 +
 mm/pgtable-generic.c                    |    2 
 mm/sparse-vmemmap.c                     |   37 ++++
 mm/sparse.c                             |    8 +
 mm/swap.c                               |   15 ++
 virt/kvm/kvm_main.c                     |   47 ++---
 81 files changed, 1302 insertions(+), 417 deletions(-)

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[PATCH -mm 01/25] pmem, dax: clean up clear_pmem()

[Dan Williams]

Both, __dax_pmd_fault, and clear_pmem() were taking special steps to
clear memory a page at a time to take advantage of non-temporal
clear_page() implementations.  However, x86_64 does not use
non-temporal instructions for clear_page(), and arch_clear_pmem() was
always incurring the cost of __arch_wb_cache_pmem().

Clean up the assumption that doing clear_pmem() a page at a time is more
performant.

Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/x86/include/asm/pmem.h |    7 +------
 fs/dax.c                    |    4 +---
 2 files changed, 2 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/pmem.h b/arch/x86/include/asm/pmem.h
index d8ce3ec816ab..1544fabcd7f9 100644
--- a/arch/x86/include/asm/pmem.h
+++ b/arch/x86/include/asm/pmem.h
@@ -132,12 +132,7 @@ static inline void arch_clear_pmem(void __pmem *addr, size_t size)
 {
 	void *vaddr = (void __force *)addr;
 
-	/* TODO: implement the zeroing via non-temporal writes */
-	if (size == PAGE_SIZE && ((unsigned long)vaddr & ~PAGE_MASK) == 0)
-		clear_page(vaddr);
-	else
-		memset(vaddr, 0, size);
-
+	memset(vaddr, 0, size);
 	__arch_wb_cache_pmem(vaddr, size);
 }
 
diff --git a/fs/dax.c b/fs/dax.c
index 43671b68220e..19492cc65a30 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -641,9 +641,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 			goto fallback;
 
 		if (buffer_unwritten(&bh) || buffer_new(&bh)) {
-			int i;
-			for (i = 0; i < PTRS_PER_PMD; i++)
-				clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE);
+			clear_pmem(kaddr, PMD_SIZE);
 			wmb_pmem();
 			count_vm_event(PGMAJFAULT);
 			mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);

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[PATCH -mm 02/25] dax: increase granularity of dax_clear_blocks() operations

[Dan Williams]

dax_clear_blocks is currently performing a cond_resched() after every
PAGE_SIZE memset.  We need not check so frequently, for example md-raid
only calls cond_resched() at stripe granularity.  Also, in preparation
for introducing a dax_map_atomic() operation that temporarily pins a dax
mapping move the call to cond_resched() to the outer loop.

Reviewed-by: Jan Kara <jack@suse.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 fs/dax.c |   22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 19492cc65a30..e11d88835bb2 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -28,6 +28,7 @@
 #include <linux/sched.h>
 #include <linux/uio.h>
 #include <linux/vmstat.h>
+#include <linux/sizes.h>
 
 /*
  * dax_clear_blocks() is called from within transaction context from XFS,
@@ -43,24 +44,17 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
 	do {
 		void __pmem *addr;
 		unsigned long pfn;
-		long count;
+		long count, sz;
 
 		count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
 		if (count < 0)
 			return count;
-		BUG_ON(size < count);
-		while (count > 0) {
-			unsigned pgsz = PAGE_SIZE - offset_in_page(addr);
-			if (pgsz > count)
-				pgsz = count;
-			clear_pmem(addr, pgsz);
-			addr += pgsz;
-			size -= pgsz;
-			count -= pgsz;
-			BUG_ON(pgsz & 511);
-			sector += pgsz / 512;
-			cond_resched();
-		}
+		sz = min_t(long, count, SZ_1M);
+		clear_pmem(addr, sz);
+		size -= sz;
+		BUG_ON(sz & 511);
+		sector += sz / 512;
+		cond_resched();
 	} while (size);
 
 	wmb_pmem();

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[PATCH -mm 03/25] dax: guarantee page aligned results from bdev_direct_access()

[Dan Williams]

If a ->direct_access() implementation ever returns a map count less than
PAGE_SIZE, catch the error in bdev_direct_access().  This simplifies
error checking in upper layers.

Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 fs/block_dev.c |    2 ++
 fs/dax.c       |    1 -
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index c27362de0039..653d14ccc86e 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -489,6 +489,8 @@ long bdev_direct_access(struct block_device *bdev, sector_t sector,
 	avail = ops->direct_access(bdev, sector, addr, pfn);
 	if (!avail)
 		return -ERANGE;
+	if (avail > 0 && avail & ~PAGE_MASK)
+		return -ENXIO;
 	return min(avail, size);
 }
 EXPORT_SYMBOL_GPL(bdev_direct_access);
diff --git a/fs/dax.c b/fs/dax.c
index e11d88835bb2..6e498c2570bf 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -52,7 +52,6 @@ int dax_clear_blocks(struct inode *inode, sector_t block, long size)
 		sz = min_t(long, count, SZ_1M);
 		clear_pmem(addr, sz);
 		size -= sz;
-		BUG_ON(sz & 511);
 		sector += sz / 512;
 		cond_resched();
 	} while (size);

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[PATCH -mm 04/25] dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()

[Dan Williams]

The DAX implementation needs to protect new calls to ->direct_access()
and usage of its return value against the driver for the underlying
block device being disabled.  Use blk_queue_enter()/blk_queue_exit() to
hold off blk_cleanup_queue() from proceeding, or otherwise fail new
mapping requests if the request_queue is being torn down.

This also introduces blk_dax_ctl to simplify the interface from fs/dax.c
through dax_map_atomic() to bdev_direct_access().

Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
[willy: fix read() of a hole]
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 fs/block_dev.c         |   13 +--
 fs/dax.c               |  208 ++++++++++++++++++++++++++++++------------------
 include/linux/blkdev.h |   17 +++-
 3 files changed, 150 insertions(+), 88 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 653d14ccc86e..774851b1b201 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -450,10 +450,7 @@ EXPORT_SYMBOL_GPL(bdev_write_page);
 /**
  * bdev_direct_access() - Get the address for directly-accessibly memory
  * @bdev: The device containing the memory
- * @sector: The offset within the device
- * @addr: Where to put the address of the memory
- * @pfn: The Page Frame Number for the memory
- * @size: The number of bytes requested
+ * @dax: control and output parameters for ->direct_access
  *
  * If a block device is made up of directly addressable memory, this function
  * will tell the caller the PFN and the address of the memory.  The address
@@ -464,10 +461,10 @@ EXPORT_SYMBOL_GPL(bdev_write_page);
  * Return: negative errno if an error occurs, otherwise the number of bytes
  * accessible at this address.
  */
-long bdev_direct_access(struct block_device *bdev, sector_t sector,
-			void __pmem **addr, unsigned long *pfn, long size)
+long bdev_direct_access(struct block_device *bdev, struct blk_dax_ctl *dax)
 {
-	long avail;
+	sector_t sector = dax->sector;
+	long avail, size = dax->size;
 	const struct block_device_operations *ops = bdev->bd_disk->fops;
 
 	/*
@@ -486,7 +483,7 @@ long bdev_direct_access(struct block_device *bdev, sector_t sector,
 	sector += get_start_sect(bdev);
 	if (sector % (PAGE_SIZE / 512))
 		return -EINVAL;
-	avail = ops->direct_access(bdev, sector, addr, pfn);
+	avail = ops->direct_access(bdev, sector, &dax->addr, &dax->pfn);
 	if (!avail)
 		return -ERANGE;
 	if (avail > 0 && avail & ~PAGE_MASK)
diff --git a/fs/dax.c b/fs/dax.c
index 6e498c2570bf..68b04de71d19 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -30,45 +30,65 @@
 #include <linux/vmstat.h>
 #include <linux/sizes.h>
 
+static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax)
+{
+	struct request_queue *q = bdev->bd_queue;
+	long rc = -EIO;
+
+	dax->addr = (void __pmem *) ERR_PTR(-EIO);
+	if (blk_queue_enter(q, GFP_NOWAIT) != 0)
+		return rc;
+
+	rc = bdev_direct_access(bdev, dax);
+	if (rc < 0) {
+		dax->addr = (void __pmem *) ERR_PTR(rc);
+		blk_queue_exit(q);
+		return rc;
+	}
+	return rc;
+}
+
+static void dax_unmap_atomic(struct block_device *bdev,
+		const struct blk_dax_ctl *dax)
+{
+	if (IS_ERR(dax->addr))
+		return;
+	blk_queue_exit(bdev->bd_queue);
+}
+
 /*
  * dax_clear_blocks() is called from within transaction context from XFS,
  * and hence this means the stack from this point must follow GFP_NOFS
  * semantics for all operations.
  */
-int dax_clear_blocks(struct inode *inode, sector_t block, long size)
+int dax_clear_blocks(struct inode *inode, sector_t block, long _size)
 {
 	struct block_device *bdev = inode->i_sb->s_bdev;
-	sector_t sector = block << (inode->i_blkbits - 9);
+	struct blk_dax_ctl dax = {
+		.sector = block << (inode->i_blkbits - 9),
+		.size = _size,
+	};
 
 	might_sleep();
 	do {
-		void __pmem *addr;
-		unsigned long pfn;
 		long count, sz;
 
-		count = bdev_direct_access(bdev, sector, &addr, &pfn, size);
+		count = dax_map_atomic(bdev, &dax);
 		if (count < 0)
 			return count;
 		sz = min_t(long, count, SZ_1M);
-		clear_pmem(addr, sz);
-		size -= sz;
-		sector += sz / 512;
+		clear_pmem(dax.addr, sz);
+		dax.size -= sz;
+		dax.sector += sz / 512;
+		dax_unmap_atomic(bdev, &dax);
 		cond_resched();
-	} while (size);
+	} while (dax.size);
 
 	wmb_pmem();
 	return 0;
 }
 EXPORT_SYMBOL_GPL(dax_clear_blocks);
 
-static long dax_get_addr(struct buffer_head *bh, void __pmem **addr,
-		unsigned blkbits)
-{
-	unsigned long pfn;
-	sector_t sector = bh->b_blocknr << (blkbits - 9);
-	return bdev_direct_access(bh->b_bdev, sector, addr, &pfn, bh->b_size);
-}
-
 /* the clear_pmem() calls are ordered by a wmb_pmem() in the caller */
 static void dax_new_buf(void __pmem *addr, unsigned size, unsigned first,
 		loff_t pos, loff_t end)
@@ -98,19 +118,29 @@ static bool buffer_size_valid(struct buffer_head *bh)
 	return bh->b_state != 0;
 }
 
+
+static sector_t to_sector(const struct buffer_head *bh,
+		const struct inode *inode)
+{
+	sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
+
+	return sector;
+}
+
 static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
 		      loff_t start, loff_t end, get_block_t get_block,
 		      struct buffer_head *bh)
 {
-	ssize_t retval = 0;
-	loff_t pos = start;
-	loff_t max = start;
-	loff_t bh_max = start;
-	void __pmem *addr;
-	bool hole = false;
-	bool need_wmb = false;
-
-	if (iov_iter_rw(iter) != WRITE)
+	loff_t pos = start, max = start, bh_max = start;
+	bool hole = false, need_wmb = false;
+	struct block_device *bdev = NULL;
+	int rw = iov_iter_rw(iter), rc;
+	long map_len = 0;
+	struct blk_dax_ctl dax = {
+		.addr = (void __pmem *) ERR_PTR(-EIO),
+	};
+
+	if (rw == READ)
 		end = min(end, i_size_read(inode));
 
 	while (pos < end) {
@@ -125,13 +155,13 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
 			if (pos == bh_max) {
 				bh->b_size = PAGE_ALIGN(end - pos);
 				bh->b_state = 0;
-				retval = get_block(inode, block, bh,
-						   iov_iter_rw(iter) == WRITE);
-				if (retval)
+				rc = get_block(inode, block, bh, rw == WRITE);
+				if (rc)
 					break;
 				if (!buffer_size_valid(bh))
 					bh->b_size = 1 << blkbits;
 				bh_max = pos - first + bh->b_size;
+				bdev = bh->b_bdev;
 			} else {
 				unsigned done = bh->b_size -
 						(bh_max - (pos - first));
@@ -139,47 +169,53 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
 				bh->b_size -= done;
 			}
 
-			hole = iov_iter_rw(iter) != WRITE && !buffer_written(bh);
+			hole = rw == READ && !buffer_written(bh);
 			if (hole) {
-				addr = NULL;
 				size = bh->b_size - first;
 			} else {
-				retval = dax_get_addr(bh, &addr, blkbits);
-				if (retval < 0)
+				dax_unmap_atomic(bdev, &dax);
+				dax.sector = to_sector(bh, inode);
+				dax.size = bh->b_size;
+				map_len = dax_map_atomic(bdev, &dax);
+				if (map_len < 0) {
+					rc = map_len;
 					break;
+				}
 				if (buffer_unwritten(bh) || buffer_new(bh)) {
-					dax_new_buf(addr, retval, first, pos,
-									end);
+					dax_new_buf(dax.addr, map_len, first,
+							pos, end);
 					need_wmb = true;
 				}
-				addr += first;
-				size = retval - first;
+				dax.addr += first;
+				size = map_len - first;
 			}
 			max = min(pos + size, end);
 		}
 
 		if (iov_iter_rw(iter) == WRITE) {
-			len = copy_from_iter_pmem(addr, max - pos, iter);
+			len = copy_from_iter_pmem(dax.addr, max - pos, iter);
 			need_wmb = true;
 		} else if (!hole)
-			len = copy_to_iter((void __force *)addr, max - pos,
+			len = copy_to_iter((void __force *) dax.addr, max - pos,
 					iter);
 		else
 			len = iov_iter_zero(max - pos, iter);
 
 		if (!len) {
-			retval = -EFAULT;
+			rc = -EFAULT;
 			break;
 		}
 
 		pos += len;
-		addr += len;
+		if (!IS_ERR(dax.addr))
+			dax.addr += len;
 	}
 
 	if (need_wmb)
 		wmb_pmem();
+	dax_unmap_atomic(bdev, &dax);
 
-	return (pos == start) ? retval : pos - start;
+	return (pos == start) ? rc : pos - start;
 }
 
 /**
@@ -268,28 +304,35 @@ static int dax_load_hole(struct address_space *mapping, struct page *page,
 	return VM_FAULT_LOCKED;
 }
 
-static int copy_user_bh(struct page *to, struct buffer_head *bh,
-			unsigned blkbits, unsigned long vaddr)
+static int copy_user_bh(struct page *to, struct inode *inode,
+		struct buffer_head *bh, unsigned long vaddr)
 {
-	void __pmem *vfrom;
+	struct blk_dax_ctl dax = {
+		.sector = to_sector(bh, inode),
+		.size = bh->b_size,
+	};
+	struct block_device *bdev = bh->b_bdev;
 	void *vto;
 
-	if (dax_get_addr(bh, &vfrom, blkbits) < 0)
-		return -EIO;
+	if (dax_map_atomic(bdev, &dax) < 0)
+		return PTR_ERR(dax.addr);
 	vto = kmap_atomic(to);
-	copy_user_page(vto, (void __force *)vfrom, vaddr, to);
+	copy_user_page(vto, (void __force *)dax.addr, vaddr, to);
 	kunmap_atomic(vto);
+	dax_unmap_atomic(bdev, &dax);
 	return 0;
 }
 
 static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
 			struct vm_area_struct *vma, struct vm_fault *vmf)
 {
-	struct address_space *mapping = inode->i_mapping;
-	sector_t sector = bh->b_blocknr << (inode->i_blkbits - 9);
 	unsigned long vaddr = (unsigned long)vmf->virtual_address;
-	void __pmem *addr;
-	unsigned long pfn;
+	struct address_space *mapping = inode->i_mapping;
+	struct block_device *bdev = bh->b_bdev;
+	struct blk_dax_ctl dax = {
+		.sector = to_sector(bh, inode),
+		.size = bh->b_size,
+	};
 	pgoff_t size;
 	int error;
 
@@ -308,20 +351,18 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
 		goto out;
 	}
 
-	error = bdev_direct_access(bh->b_bdev, sector, &addr, &pfn, bh->b_size);
-	if (error < 0)
-		goto out;
-	if (error < PAGE_SIZE) {
-		error = -EIO;
+	if (dax_map_atomic(bdev, &dax) < 0) {
+		error = PTR_ERR(dax.addr);
 		goto out;
 	}
 
 	if (buffer_unwritten(bh) || buffer_new(bh)) {
-		clear_pmem(addr, PAGE_SIZE);
+		clear_pmem(dax.addr, PAGE_SIZE);
 		wmb_pmem();
 	}
+	dax_unmap_atomic(bdev, &dax);
 
-	error = vm_insert_mixed(vma, vaddr, pfn);
+	error = vm_insert_mixed(vma, vaddr, dax.pfn);
 
  out:
 	i_mmap_unlock_read(mapping);
@@ -415,7 +456,7 @@ int __dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
 	if (vmf->cow_page) {
 		struct page *new_page = vmf->cow_page;
 		if (buffer_written(&bh))
-			error = copy_user_bh(new_page, &bh, blkbits, vaddr);
+			error = copy_user_bh(new_page, inode, &bh, vaddr);
 		else
 			clear_user_highpage(new_page, vaddr);
 		if (error)
@@ -527,11 +568,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	unsigned blkbits = inode->i_blkbits;
 	unsigned long pmd_addr = address & PMD_MASK;
 	bool write = flags & FAULT_FLAG_WRITE;
-	long length;
-	void __pmem *kaddr;
+	struct block_device *bdev;
 	pgoff_t size, pgoff;
-	sector_t block, sector;
-	unsigned long pfn;
+	sector_t block;
 	int result = 0;
 
 	/* dax pmd mappings are broken wrt gup and fork */
@@ -559,9 +598,9 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
 
 	bh.b_size = PMD_SIZE;
-	length = get_block(inode, block, &bh, write);
-	if (length)
+	if (get_block(inode, block, &bh, write) != 0)
 		return VM_FAULT_SIGBUS;
+	bdev = bh.b_bdev;
 	i_mmap_lock_read(mapping);
 
 	/*
@@ -616,32 +655,40 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		result = VM_FAULT_NOPAGE;
 		spin_unlock(ptl);
 	} else {
-		sector = bh.b_blocknr << (blkbits - 9);
-		length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn,
-						bh.b_size);
+		struct blk_dax_ctl dax = {
+			.sector = to_sector(&bh, inode),
+			.size = PMD_SIZE,
+		};
+		long length = dax_map_atomic(bdev, &dax);
+
 		if (length < 0) {
 			result = VM_FAULT_SIGBUS;
 			goto out;
 		}
-		if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR))
+		if ((length < PMD_SIZE) || (dax.pfn & PG_PMD_COLOUR)) {
+			dax_unmap_atomic(bdev, &dax);
 			goto fallback;
+		}
 
 		/*
 		 * TODO: teach vmf_insert_pfn_pmd() to support
 		 * 'pte_special' for pmds
 		 */
-		if (pfn_valid(pfn))
+		if (pfn_valid(dax.pfn)) {
+			dax_unmap_atomic(bdev, &dax);
 			goto fallback;
+		}
 
 		if (buffer_unwritten(&bh) || buffer_new(&bh)) {
-			clear_pmem(kaddr, PMD_SIZE);
+			clear_pmem(dax.addr, PMD_SIZE);
 			wmb_pmem();
 			count_vm_event(PGMAJFAULT);
 			mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
 			result |= VM_FAULT_MAJOR;
 		}
+		dax_unmap_atomic(bdev, &dax);
 
-		result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write);
+		result |= vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
 	}
 
  out:
@@ -743,12 +790,17 @@ int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length,
 	if (err < 0)
 		return err;
 	if (buffer_written(&bh)) {
-		void __pmem *addr;
-		err = dax_get_addr(&bh, &addr, inode->i_blkbits);
-		if (err < 0)
-			return err;
-		clear_pmem(addr + offset, length);
+		struct block_device *bdev = bh.b_bdev;
+		struct blk_dax_ctl dax = {
+			.sector = to_sector(&bh, inode),
+			.size = PAGE_CACHE_SIZE,
+		};
+
+		if (dax_map_atomic(bdev, &dax) < 0)
+			return PTR_ERR(dax.addr);
+		clear_pmem(dax.addr + offset, length);
 		wmb_pmem();
+		dax_unmap_atomic(bdev, &dax);
 	}
 
 	return 0;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 12df3da13fb2..ae94b18999ab 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1617,6 +1617,20 @@ static inline bool integrity_req_gap_front_merge(struct request *req,
 
 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 
+/**
+ * struct blk_dax_ctl - control and output parameters for ->direct_access
+ * @sector: (input) offset relative to a block_device
+ * @addr: (output) kernel virtual address for @sector populated by driver
+ * @pfn: (output) page frame number for @addr populated by driver
+ * @size: (input) number of bytes requested
+ */
+struct blk_dax_ctl {
+	sector_t sector;
+	void __pmem *addr;
+	long size;
+	unsigned long pfn;
+};
+
 struct block_device_operations {
 	int (*open) (struct block_device *, fmode_t);
 	void (*release) (struct gendisk *, fmode_t);
@@ -1643,8 +1657,7 @@ extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
 extern int bdev_read_page(struct block_device *, sector_t, struct page *);
 extern int bdev_write_page(struct block_device *, sector_t, struct page *,
 						struct writeback_control *);
-extern long bdev_direct_access(struct block_device *, sector_t,
-		void __pmem **addr, unsigned long *pfn, long size);
+extern long bdev_direct_access(struct block_device *, struct blk_dax_ctl *);
 #else /* CONFIG_BLOCK */
 
 struct block_device;

--
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[PATCH -mm 05/25] mm, dax: fix livelock, allow dax pmd mappings to become writeable

[Dan Williams]

From: Ross Zwisler <ross.zwisler@linux.intel.com>

Prior to this change DAX PMD mappings that were made read-only were
never able to be made writable again.  This is because the code in
insert_pfn_pmd() that calls pmd_mkdirty() and pmd_mkwrite() would skip
these calls if the PMD already existed in the page table.

Instead, if we are doing a write always mark the PMD entry as dirty and
writeable.  Without this code we can get into a condition where we mark
the PMD as read-only, and then on a subsequent write fault we get into
an infinite loop of PMD faults where we try unsuccessfully to make the
PMD writeable.

Reported-by: Jeff Moyer <jmoyer@redhat.com>
Reported-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 mm/huge_memory.c |   14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index b41793b12a2d..70323839bd0d 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -967,15 +967,13 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 	spinlock_t *ptl;
 
 	ptl = pmd_lock(mm, pmd);
-	if (pmd_none(*pmd)) {
-		entry = pmd_mkhuge(pfn_pmd(pfn, prot));
-		if (write) {
-			entry = pmd_mkyoung(pmd_mkdirty(entry));
-			entry = maybe_pmd_mkwrite(entry, vma);
-		}
-		set_pmd_at(mm, addr, pmd, entry);
-		update_mmu_cache_pmd(vma, addr, pmd);
+	entry = pmd_mkhuge(pfn_pmd(pfn, prot));
+	if (write) {
+		entry = pmd_mkyoung(pmd_mkdirty(entry));
+		entry = maybe_pmd_mkwrite(entry, vma);
 	}
+	set_pmd_at(mm, addr, pmd, entry);
+	update_mmu_cache_pmd(vma, addr, pmd);
 	spin_unlock(ptl);
 }
 

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[PATCH -mm 06/25] dax: Split pmd map when fallback on COW

[Dan Williams]

From: Toshi Kani <toshi.kani@hpe.com>

An infinite loop of PMD faults was observed when attempted to
mlock() a private read-only PMD mmap'd range of a DAX file.

__dax_pmd_fault() simply returns with VM_FAULT_FALLBACK when
falling back to PTE on COW.  However, __handle_mm_fault()
returns without falling back to handle_pte_fault() because
a PMD map is present in this case.

Change __dax_pmd_fault() to split the PMD map, if present,
before returning with VM_FAULT_FALLBACK.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 fs/dax.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index 68b04de71d19..88e7b3bfef21 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -578,8 +578,10 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		return VM_FAULT_FALLBACK;
 
 	/* Fall back to PTEs if we're going to COW */
-	if (write && !(vma->vm_flags & VM_SHARED))
+	if (write && !(vma->vm_flags & VM_SHARED)) {
+		split_huge_pmd(vma, pmd, address);
 		return VM_FAULT_FALLBACK;
+	}
 	/* If the PMD would extend outside the VMA */
 	if (pmd_addr < vma->vm_start)
 		return VM_FAULT_FALLBACK;

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[PATCH -mm 07/25] um: kill pfn_t

[Dan Williams]

The core has developed a need for a "pfn_t" type [1].  Convert the usage
of pfn_t by usermode-linux to an unsigned long, and update pfn_to_phys()
to drop its expectation of a typed pfn.

[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002199.html

Cc: Dave Hansen <dave@sr71.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/um/include/asm/page.h           |    7 +++----
 arch/um/include/asm/pgtable-3level.h |    4 ++--
 arch/um/include/asm/pgtable.h        |    2 +-
 3 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h
index 71c5d132062a..e13d41c392ae 100644
--- a/arch/um/include/asm/page.h
+++ b/arch/um/include/asm/page.h
@@ -18,6 +18,7 @@
 
 struct page;
 
+#include <linux/pfn.h>
 #include <linux/types.h>
 #include <asm/vm-flags.h>
 
@@ -52,7 +53,6 @@ typedef struct { unsigned long pgd; } pgd_t;
 #define pmd_val(x)	((x).pmd)
 #define __pmd(x) ((pmd_t) { (x) } )
 
-typedef unsigned long long pfn_t;
 typedef unsigned long long phys_t;
 
 #else
@@ -76,7 +76,6 @@ typedef struct { unsigned long pmd; } pmd_t;
 #define pte_is_zero(p) (!((p).pte & ~_PAGE_NEWPAGE))
 #define pte_set_val(p, phys, prot) (p).pte = (phys | pgprot_val(prot))
 
-typedef unsigned long pfn_t;
 typedef unsigned long phys_t;
 
 #endif
@@ -109,8 +108,8 @@ extern unsigned long uml_physmem;
 #define __pa(virt) to_phys((void *) (unsigned long) (virt))
 #define __va(phys) to_virt((unsigned long) (phys))
 
-#define phys_to_pfn(p) ((pfn_t) ((p) >> PAGE_SHIFT))
-#define pfn_to_phys(pfn) ((phys_t) ((pfn) << PAGE_SHIFT))
+#define phys_to_pfn(p) ((p) >> PAGE_SHIFT)
+#define pfn_to_phys(pfn) PFN_PHYS(pfn)
 
 #define pfn_valid(pfn) ((pfn) < max_mapnr)
 #define virt_addr_valid(v) pfn_valid(phys_to_pfn(__pa(v)))
diff --git a/arch/um/include/asm/pgtable-3level.h b/arch/um/include/asm/pgtable-3level.h
index 2b4274e7c095..bae8523a162f 100644
--- a/arch/um/include/asm/pgtable-3level.h
+++ b/arch/um/include/asm/pgtable-3level.h
@@ -98,7 +98,7 @@ static inline unsigned long pte_pfn(pte_t pte)
 	return phys_to_pfn(pte_val(pte));
 }
 
-static inline pte_t pfn_pte(pfn_t page_nr, pgprot_t pgprot)
+static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
 {
 	pte_t pte;
 	phys_t phys = pfn_to_phys(page_nr);
@@ -107,7 +107,7 @@ static inline pte_t pfn_pte(pfn_t page_nr, pgprot_t pgprot)
 	return pte;
 }
 
-static inline pmd_t pfn_pmd(pfn_t page_nr, pgprot_t pgprot)
+static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
 {
 	return __pmd((page_nr << PAGE_SHIFT) | pgprot_val(pgprot));
 }
diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index 18eb9924dda3..7485398d0737 100644
--- a/arch/um/include/asm/pgtable.h
+++ b/arch/um/include/asm/pgtable.h
@@ -271,7 +271,7 @@ static inline int pte_same(pte_t pte_a, pte_t pte_b)
 
 #define phys_to_page(phys) pfn_to_page(phys_to_pfn(phys))
 #define __virt_to_page(virt) phys_to_page(__pa(virt))
-#define page_to_phys(page) pfn_to_phys((pfn_t) page_to_pfn(page))
+#define page_to_phys(page) pfn_to_phys(page_to_pfn(page))
 #define virt_to_page(addr) __virt_to_page((const unsigned long) addr)
 
 #define mk_pte(page, pgprot) \

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[PATCH -mm 08/25] kvm: rename pfn_t to kvm_pfn_t

[Dan Williams]

The core has developed a need for a "pfn_t" type [1].  Move the existing
pfn_t in KVM to kvm_pfn_t [2].

[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002199.html
[2]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002218.html

Cc: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/arm/include/asm/kvm_mmu.h        |    5 ++--
 arch/arm/kvm/mmu.c                    |   10 ++++---
 arch/arm64/include/asm/kvm_mmu.h      |    3 +-
 arch/mips/include/asm/kvm_host.h      |    6 ++--
 arch/mips/kvm/emulate.c               |    2 +
 arch/mips/kvm/tlb.c                   |   14 +++++-----
 arch/powerpc/include/asm/kvm_book3s.h |    4 +--
 arch/powerpc/include/asm/kvm_ppc.h    |    2 +
 arch/powerpc/kvm/book3s.c             |    6 ++--
 arch/powerpc/kvm/book3s_32_mmu_host.c |    2 +
 arch/powerpc/kvm/book3s_64_mmu_host.c |    2 +
 arch/powerpc/kvm/e500.h               |    2 +
 arch/powerpc/kvm/e500_mmu_host.c      |    8 +++---
 arch/powerpc/kvm/trace_pr.h           |    2 +
 arch/x86/kvm/iommu.c                  |   11 ++++----
 arch/x86/kvm/mmu.c                    |   37 +++++++++++++-------------
 arch/x86/kvm/mmu_audit.c              |    2 +
 arch/x86/kvm/paging_tmpl.h            |    6 ++--
 arch/x86/kvm/vmx.c                    |    2 +
 arch/x86/kvm/x86.c                    |    2 +
 include/linux/kvm_host.h              |   37 +++++++++++++-------------
 include/linux/kvm_types.h             |    2 +
 virt/kvm/kvm_main.c                   |   47 +++++++++++++++++----------------
 23 files changed, 110 insertions(+), 104 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 405aa1883307..8ebd282dfc2b 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -182,7 +182,8 @@ static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
 	return (vcpu->arch.cp15[c1_SCTLR] & 0b101) == 0b101;
 }
 
-static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu, pfn_t pfn,
+static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu,
+					       kvm_pfn_t pfn,
 					       unsigned long size,
 					       bool ipa_uncached)
 {
@@ -246,7 +247,7 @@ static inline void __kvm_flush_dcache_pte(pte_t pte)
 static inline void __kvm_flush_dcache_pmd(pmd_t pmd)
 {
 	unsigned long size = PMD_SIZE;
-	pfn_t pfn = pmd_pfn(pmd);
+	kvm_pfn_t pfn = pmd_pfn(pmd);
 
 	while (size) {
 		void *va = kmap_atomic_pfn(pfn);
diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 7dace909d5cf..b821f4b60f08 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -992,9 +992,9 @@ out:
 	return ret;
 }
 
-static bool transparent_hugepage_adjust(pfn_t *pfnp, phys_addr_t *ipap)
+static bool transparent_hugepage_adjust(kvm_pfn_t *pfnp, phys_addr_t *ipap)
 {
-	pfn_t pfn = *pfnp;
+	kvm_pfn_t pfn = *pfnp;
 	gfn_t gfn = *ipap >> PAGE_SHIFT;
 
 	if (PageTransCompound(pfn_to_page(pfn))) {
@@ -1201,7 +1201,7 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 	kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
 }
 
-static void coherent_cache_guest_page(struct kvm_vcpu *vcpu, pfn_t pfn,
+static void coherent_cache_guest_page(struct kvm_vcpu *vcpu, kvm_pfn_t pfn,
 				      unsigned long size, bool uncached)
 {
 	__coherent_cache_guest_page(vcpu, pfn, size, uncached);
@@ -1218,7 +1218,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	struct kvm *kvm = vcpu->kvm;
 	struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
 	struct vm_area_struct *vma;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	pgprot_t mem_type = PAGE_S2;
 	bool fault_ipa_uncached;
 	bool logging_active = memslot_is_logging(memslot);
@@ -1346,7 +1346,7 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
 {
 	pmd_t *pmd;
 	pte_t *pte;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	bool pfn_valid = false;
 
 	trace_kvm_access_fault(fault_ipa);
diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 61505676d085..385fc8cef82d 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -230,7 +230,8 @@ static inline bool vcpu_has_cache_enabled(struct kvm_vcpu *vcpu)
 	return (vcpu_sys_reg(vcpu, SCTLR_EL1) & 0b101) == 0b101;
 }
 
-static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu, pfn_t pfn,
+static inline void __coherent_cache_guest_page(struct kvm_vcpu *vcpu,
+					       kvm_pfn_t pfn,
 					       unsigned long size,
 					       bool ipa_uncached)
 {
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 6ded8d347af9..7c191443c7ea 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -101,9 +101,9 @@
 #define CAUSEF_DC			(_ULCAST_(1) << 27)
 
 extern atomic_t kvm_mips_instance;
-extern pfn_t(*kvm_mips_gfn_to_pfn) (struct kvm *kvm, gfn_t gfn);
-extern void (*kvm_mips_release_pfn_clean) (pfn_t pfn);
-extern bool(*kvm_mips_is_error_pfn) (pfn_t pfn);
+extern kvm_pfn_t (*kvm_mips_gfn_to_pfn)(struct kvm *kvm, gfn_t gfn);
+extern void (*kvm_mips_release_pfn_clean)(kvm_pfn_t pfn);
+extern bool (*kvm_mips_is_error_pfn)(kvm_pfn_t pfn);
 
 struct kvm_vm_stat {
 	u32 remote_tlb_flush;
diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c
index 41b1b090f56f..1b675c7ce89f 100644
--- a/arch/mips/kvm/emulate.c
+++ b/arch/mips/kvm/emulate.c
@@ -1525,7 +1525,7 @@ int kvm_mips_sync_icache(unsigned long va, struct kvm_vcpu *vcpu)
 	struct kvm *kvm = vcpu->kvm;
 	unsigned long pa;
 	gfn_t gfn;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 
 	gfn = va >> PAGE_SHIFT;
 
diff --git a/arch/mips/kvm/tlb.c b/arch/mips/kvm/tlb.c
index aed0ac2a4972..570479c03bdc 100644
--- a/arch/mips/kvm/tlb.c
+++ b/arch/mips/kvm/tlb.c
@@ -38,13 +38,13 @@ atomic_t kvm_mips_instance;
 EXPORT_SYMBOL(kvm_mips_instance);
 
 /* These function pointers are initialized once the KVM module is loaded */
-pfn_t (*kvm_mips_gfn_to_pfn)(struct kvm *kvm, gfn_t gfn);
+kvm_pfn_t (*kvm_mips_gfn_to_pfn)(struct kvm *kvm, gfn_t gfn);
 EXPORT_SYMBOL(kvm_mips_gfn_to_pfn);
 
-void (*kvm_mips_release_pfn_clean)(pfn_t pfn);
+void (*kvm_mips_release_pfn_clean)(kvm_pfn_t pfn);
 EXPORT_SYMBOL(kvm_mips_release_pfn_clean);
 
-bool (*kvm_mips_is_error_pfn)(pfn_t pfn);
+bool (*kvm_mips_is_error_pfn)(kvm_pfn_t pfn);
 EXPORT_SYMBOL(kvm_mips_is_error_pfn);
 
 uint32_t kvm_mips_get_kernel_asid(struct kvm_vcpu *vcpu)
@@ -144,7 +144,7 @@ EXPORT_SYMBOL(kvm_mips_dump_guest_tlbs);
 static int kvm_mips_map_page(struct kvm *kvm, gfn_t gfn)
 {
 	int srcu_idx, err = 0;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 
 	if (kvm->arch.guest_pmap[gfn] != KVM_INVALID_PAGE)
 		return 0;
@@ -262,7 +262,7 @@ int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
 				    struct kvm_vcpu *vcpu)
 {
 	gfn_t gfn;
-	pfn_t pfn0, pfn1;
+	kvm_pfn_t pfn0, pfn1;
 	unsigned long vaddr = 0;
 	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
 	int even;
@@ -313,7 +313,7 @@ EXPORT_SYMBOL(kvm_mips_handle_kseg0_tlb_fault);
 int kvm_mips_handle_commpage_tlb_fault(unsigned long badvaddr,
 	struct kvm_vcpu *vcpu)
 {
-	pfn_t pfn0, pfn1;
+	kvm_pfn_t pfn0, pfn1;
 	unsigned long flags, old_entryhi = 0, vaddr = 0;
 	unsigned long entrylo0 = 0, entrylo1 = 0;
 
@@ -360,7 +360,7 @@ int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
 {
 	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
 	struct kvm *kvm = vcpu->kvm;
-	pfn_t pfn0, pfn1;
+	kvm_pfn_t pfn0, pfn1;
 
 	if ((tlb->tlb_hi & VPN2_MASK) == 0) {
 		pfn0 = 0;
diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index 9fac01cb89c1..8f39796c9da8 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -154,8 +154,8 @@ extern void kvmppc_set_bat(struct kvm_vcpu *vcpu, struct kvmppc_bat *bat,
 			   bool upper, u32 val);
 extern void kvmppc_giveup_ext(struct kvm_vcpu *vcpu, ulong msr);
 extern int kvmppc_emulate_paired_single(struct kvm_run *run, struct kvm_vcpu *vcpu);
-extern pfn_t kvmppc_gpa_to_pfn(struct kvm_vcpu *vcpu, gpa_t gpa, bool writing,
-			bool *writable);
+extern kvm_pfn_t kvmppc_gpa_to_pfn(struct kvm_vcpu *vcpu, gpa_t gpa,
+			bool writing, bool *writable);
 extern void kvmppc_add_revmap_chain(struct kvm *kvm, struct revmap_entry *rev,
 			unsigned long *rmap, long pte_index, int realmode);
 extern void kvmppc_update_rmap_change(unsigned long *rmap, unsigned long psize);
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index c6ef05bd0765..2241d5357129 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -515,7 +515,7 @@ void kvmppc_claim_lpid(long lpid);
 void kvmppc_free_lpid(long lpid);
 void kvmppc_init_lpid(unsigned long nr_lpids);
 
-static inline void kvmppc_mmu_flush_icache(pfn_t pfn)
+static inline void kvmppc_mmu_flush_icache(kvm_pfn_t pfn)
 {
 	struct page *page;
 	/*
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 099c79d8c160..638c6d9be9e0 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -366,7 +366,7 @@ int kvmppc_core_prepare_to_enter(struct kvm_vcpu *vcpu)
 }
 EXPORT_SYMBOL_GPL(kvmppc_core_prepare_to_enter);
 
-pfn_t kvmppc_gpa_to_pfn(struct kvm_vcpu *vcpu, gpa_t gpa, bool writing,
+kvm_pfn_t kvmppc_gpa_to_pfn(struct kvm_vcpu *vcpu, gpa_t gpa, bool writing,
 			bool *writable)
 {
 	ulong mp_pa = vcpu->arch.magic_page_pa & KVM_PAM;
@@ -379,9 +379,9 @@ pfn_t kvmppc_gpa_to_pfn(struct kvm_vcpu *vcpu, gpa_t gpa, bool writing,
 	gpa &= ~0xFFFULL;
 	if (unlikely(mp_pa) && unlikely((gpa & KVM_PAM) == mp_pa)) {
 		ulong shared_page = ((ulong)vcpu->arch.shared) & PAGE_MASK;
-		pfn_t pfn;
+		kvm_pfn_t pfn;
 
-		pfn = (pfn_t)virt_to_phys((void*)shared_page) >> PAGE_SHIFT;
+		pfn = (kvm_pfn_t)virt_to_phys((void*)shared_page) >> PAGE_SHIFT;
 		get_page(pfn_to_page(pfn));
 		if (writable)
 			*writable = true;
diff --git a/arch/powerpc/kvm/book3s_32_mmu_host.c b/arch/powerpc/kvm/book3s_32_mmu_host.c
index d5c9bfeb0c9c..55c4d51ea3e2 100644
--- a/arch/powerpc/kvm/book3s_32_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_32_mmu_host.c
@@ -142,7 +142,7 @@ extern char etext[];
 int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte,
 			bool iswrite)
 {
-	pfn_t hpaddr;
+	kvm_pfn_t hpaddr;
 	u64 vpn;
 	u64 vsid;
 	struct kvmppc_sid_map *map;
diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/book3s_64_mmu_host.c
index 79ad35abd196..913cd2198fa6 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_host.c
@@ -83,7 +83,7 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte,
 			bool iswrite)
 {
 	unsigned long vpn;
-	pfn_t hpaddr;
+	kvm_pfn_t hpaddr;
 	ulong hash, hpteg;
 	u64 vsid;
 	int ret;
diff --git a/arch/powerpc/kvm/e500.h b/arch/powerpc/kvm/e500.h
index 72920bed3ac6..94f04fcb373e 100644
--- a/arch/powerpc/kvm/e500.h
+++ b/arch/powerpc/kvm/e500.h
@@ -41,7 +41,7 @@ enum vcpu_ftr {
 #define E500_TLB_MAS2_ATTR	(0x7f)
 
 struct tlbe_ref {
-	pfn_t pfn;		/* valid only for TLB0, except briefly */
+	kvm_pfn_t pfn;		/* valid only for TLB0, except briefly */
 	unsigned int flags;	/* E500_TLB_* */
 };
 
diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 34c43fff4adb..b0333cc737dd 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -163,9 +163,9 @@ void kvmppc_map_magic(struct kvm_vcpu *vcpu)
 	struct kvm_book3e_206_tlb_entry magic;
 	ulong shared_page = ((ulong)vcpu->arch.shared) & PAGE_MASK;
 	unsigned int stid;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 
-	pfn = (pfn_t)virt_to_phys((void *)shared_page) >> PAGE_SHIFT;
+	pfn = (kvm_pfn_t)virt_to_phys((void *)shared_page) >> PAGE_SHIFT;
 	get_page(pfn_to_page(pfn));
 
 	preempt_disable();
@@ -246,7 +246,7 @@ static inline int tlbe_is_writable(struct kvm_book3e_206_tlb_entry *tlbe)
 
 static inline void kvmppc_e500_ref_setup(struct tlbe_ref *ref,
 					 struct kvm_book3e_206_tlb_entry *gtlbe,
-					 pfn_t pfn, unsigned int wimg)
+					 kvm_pfn_t pfn, unsigned int wimg)
 {
 	ref->pfn = pfn;
 	ref->flags = E500_TLB_VALID;
@@ -309,7 +309,7 @@ static void kvmppc_e500_setup_stlbe(
 	int tsize, struct tlbe_ref *ref, u64 gvaddr,
 	struct kvm_book3e_206_tlb_entry *stlbe)
 {
-	pfn_t pfn = ref->pfn;
+	kvm_pfn_t pfn = ref->pfn;
 	u32 pr = vcpu->arch.shared->msr & MSR_PR;
 
 	BUG_ON(!(ref->flags & E500_TLB_VALID));
diff --git a/arch/powerpc/kvm/trace_pr.h b/arch/powerpc/kvm/trace_pr.h
index 810507cb688a..d44f324184fb 100644
--- a/arch/powerpc/kvm/trace_pr.h
+++ b/arch/powerpc/kvm/trace_pr.h
@@ -30,7 +30,7 @@ TRACE_EVENT(kvm_book3s_reenter,
 #ifdef CONFIG_PPC_BOOK3S_64
 
 TRACE_EVENT(kvm_book3s_64_mmu_map,
-	TP_PROTO(int rflags, ulong hpteg, ulong va, pfn_t hpaddr,
+	TP_PROTO(int rflags, ulong hpteg, ulong va, kvm_pfn_t hpaddr,
 		 struct kvmppc_pte *orig_pte),
 	TP_ARGS(rflags, hpteg, va, hpaddr, orig_pte),
 
diff --git a/arch/x86/kvm/iommu.c b/arch/x86/kvm/iommu.c
index 5c520ebf6343..a22a488b4622 100644
--- a/arch/x86/kvm/iommu.c
+++ b/arch/x86/kvm/iommu.c
@@ -43,11 +43,11 @@ static int kvm_iommu_unmap_memslots(struct kvm *kvm);
 static void kvm_iommu_put_pages(struct kvm *kvm,
 				gfn_t base_gfn, unsigned long npages);
 
-static pfn_t kvm_pin_pages(struct kvm_memory_slot *slot, gfn_t gfn,
+static kvm_pfn_t kvm_pin_pages(struct kvm_memory_slot *slot, gfn_t gfn,
 			   unsigned long npages)
 {
 	gfn_t end_gfn;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 
 	pfn     = gfn_to_pfn_memslot(slot, gfn);
 	end_gfn = gfn + npages;
@@ -62,7 +62,8 @@ static pfn_t kvm_pin_pages(struct kvm_memory_slot *slot, gfn_t gfn,
 	return pfn;
 }
 
-static void kvm_unpin_pages(struct kvm *kvm, pfn_t pfn, unsigned long npages)
+static void kvm_unpin_pages(struct kvm *kvm, kvm_pfn_t pfn,
+		unsigned long npages)
 {
 	unsigned long i;
 
@@ -73,7 +74,7 @@ static void kvm_unpin_pages(struct kvm *kvm, pfn_t pfn, unsigned long npages)
 int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
 	gfn_t gfn, end_gfn;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	int r = 0;
 	struct iommu_domain *domain = kvm->arch.iommu_domain;
 	int flags;
@@ -275,7 +276,7 @@ static void kvm_iommu_put_pages(struct kvm *kvm,
 {
 	struct iommu_domain *domain;
 	gfn_t end_gfn, gfn;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	u64 phys;
 
 	domain  = kvm->arch.iommu_domain;
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index a1a3d1907fdc..c79b790644c7 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -259,7 +259,7 @@ static unsigned get_mmio_spte_access(u64 spte)
 }
 
 static bool set_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn,
-			  pfn_t pfn, unsigned access)
+			  kvm_pfn_t pfn, unsigned access)
 {
 	if (unlikely(is_noslot_pfn(pfn))) {
 		mark_mmio_spte(vcpu, sptep, gfn, access);
@@ -320,7 +320,7 @@ static int is_last_spte(u64 pte, int level)
 	return 0;
 }
 
-static pfn_t spte_to_pfn(u64 pte)
+static kvm_pfn_t spte_to_pfn(u64 pte)
 {
 	return (pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
 }
@@ -582,7 +582,7 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte)
  */
 static int mmu_spte_clear_track_bits(u64 *sptep)
 {
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	u64 old_spte = *sptep;
 
 	if (!spte_has_volatile_bits(old_spte))
@@ -1372,7 +1372,7 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 	int need_flush = 0;
 	u64 new_spte;
 	pte_t *ptep = (pte_t *)data;
-	pfn_t new_pfn;
+	kvm_pfn_t new_pfn;
 
 	WARN_ON(pte_huge(*ptep));
 	new_pfn = pte_pfn(*ptep);
@@ -2458,7 +2458,7 @@ static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn,
 	return 0;
 }
 
-static bool kvm_is_mmio_pfn(pfn_t pfn)
+static bool kvm_is_mmio_pfn(kvm_pfn_t pfn)
 {
 	if (pfn_valid(pfn))
 		return !is_zero_pfn(pfn) && PageReserved(pfn_to_page(pfn));
@@ -2468,7 +2468,7 @@ static bool kvm_is_mmio_pfn(pfn_t pfn)
 
 static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 		    unsigned pte_access, int level,
-		    gfn_t gfn, pfn_t pfn, bool speculative,
+		    gfn_t gfn, kvm_pfn_t pfn, bool speculative,
 		    bool can_unsync, bool host_writable)
 {
 	u64 spte;
@@ -2547,7 +2547,7 @@ done:
 }
 
 static bool mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
-			 int write_fault, int level, gfn_t gfn, pfn_t pfn,
+			 int write_fault, int level, gfn_t gfn, kvm_pfn_t pfn,
 			 bool speculative, bool host_writable)
 {
 	int was_rmapped = 0;
@@ -2610,7 +2610,7 @@ static bool mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
 	return emulate;
 }
 
-static pfn_t pte_prefetch_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn,
+static kvm_pfn_t pte_prefetch_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn,
 				     bool no_dirty_log)
 {
 	struct kvm_memory_slot *slot;
@@ -2692,7 +2692,7 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep)
 }
 
 static int __direct_map(struct kvm_vcpu *vcpu, int write, int map_writable,
-			int level, gfn_t gfn, pfn_t pfn, bool prefault)
+			int level, gfn_t gfn, kvm_pfn_t pfn, bool prefault)
 {
 	struct kvm_shadow_walk_iterator iterator;
 	struct kvm_mmu_page *sp;
@@ -2740,7 +2740,7 @@ static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *
 	send_sig_info(SIGBUS, &info, tsk);
 }
 
-static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, pfn_t pfn)
+static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn)
 {
 	/*
 	 * Do not cache the mmio info caused by writing the readonly gfn
@@ -2760,9 +2760,10 @@ static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, pfn_t pfn)
 }
 
 static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu,
-					gfn_t *gfnp, pfn_t *pfnp, int *levelp)
+					gfn_t *gfnp, kvm_pfn_t *pfnp,
+					int *levelp)
 {
-	pfn_t pfn = *pfnp;
+	kvm_pfn_t pfn = *pfnp;
 	gfn_t gfn = *gfnp;
 	int level = *levelp;
 
@@ -2801,7 +2802,7 @@ static void transparent_hugepage_adjust(struct kvm_vcpu *vcpu,
 }
 
 static bool handle_abnormal_pfn(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn,
-				pfn_t pfn, unsigned access, int *ret_val)
+				kvm_pfn_t pfn, unsigned access, int *ret_val)
 {
 	bool ret = true;
 
@@ -2955,7 +2956,7 @@ exit:
 }
 
 static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
-			 gva_t gva, pfn_t *pfn, bool write, bool *writable);
+			 gva_t gva, kvm_pfn_t *pfn, bool write, bool *writable);
 static void make_mmu_pages_available(struct kvm_vcpu *vcpu);
 
 static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,
@@ -2964,7 +2965,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,
 	int r;
 	int level;
 	bool force_pt_level = false;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	unsigned long mmu_seq;
 	bool map_writable, write = error_code & PFERR_WRITE_MASK;
 
@@ -3418,7 +3419,7 @@ static bool can_do_async_pf(struct kvm_vcpu *vcpu)
 }
 
 static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
-			 gva_t gva, pfn_t *pfn, bool write, bool *writable)
+			 gva_t gva, kvm_pfn_t *pfn, bool write, bool *writable)
 {
 	struct kvm_memory_slot *slot;
 	bool async;
@@ -3456,7 +3457,7 @@ check_hugepage_cache_consistency(struct kvm_vcpu *vcpu, gfn_t gfn, int level)
 static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
 			  bool prefault)
 {
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	int r;
 	int level;
 	bool force_pt_level;
@@ -4607,7 +4608,7 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
 	u64 *sptep;
 	struct rmap_iterator iter;
 	int need_tlb_flush = 0;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	struct kvm_mmu_page *sp;
 
 restart:
diff --git a/arch/x86/kvm/mmu_audit.c b/arch/x86/kvm/mmu_audit.c
index 1cee3ec20dd2..dcce533d420c 100644
--- a/arch/x86/kvm/mmu_audit.c
+++ b/arch/x86/kvm/mmu_audit.c
@@ -97,7 +97,7 @@ static void audit_mappings(struct kvm_vcpu *vcpu, u64 *sptep, int level)
 {
 	struct kvm_mmu_page *sp;
 	gfn_t gfn;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	hpa_t hpa;
 
 	sp = page_header(__pa(sptep));
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 91e939b486d1..6c9fed957cce 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -456,7 +456,7 @@ FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 {
 	unsigned pte_access;
 	gfn_t gfn;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 
 	if (FNAME(prefetch_invalid_gpte)(vcpu, sp, spte, gpte))
 		return false;
@@ -551,7 +551,7 @@ static void FNAME(pte_prefetch)(struct kvm_vcpu *vcpu, struct guest_walker *gw,
 static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
 			 struct guest_walker *gw,
 			 int write_fault, int hlevel,
-			 pfn_t pfn, bool map_writable, bool prefault)
+			 kvm_pfn_t pfn, bool map_writable, bool prefault)
 {
 	struct kvm_mmu_page *sp = NULL;
 	struct kvm_shadow_walk_iterator it;
@@ -694,7 +694,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
 	int user_fault = error_code & PFERR_USER_MASK;
 	struct guest_walker walker;
 	int r;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 	int level = PT_PAGE_TABLE_LEVEL;
 	bool force_pt_level = false;
 	unsigned long mmu_seq;
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1a8bfaab89c7..98d59459f626 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4185,7 +4185,7 @@ out:
 static int init_rmode_identity_map(struct kvm *kvm)
 {
 	int i, idx, r = 0;
-	pfn_t identity_map_pfn;
+	kvm_pfn_t identity_map_pfn;
 	u32 tmp;
 
 	if (!enable_ept)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f1d6501180ec..b0b51751d7b1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5129,7 +5129,7 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gva_t cr2,
 				  int emulation_type)
 {
 	gpa_t gpa = cr2;
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 
 	if (emulation_type & EMULTYPE_NO_REEXECUTE)
 		return false;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 590c46e672df..08df2fa794ca 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -66,7 +66,7 @@
  * error pfns indicate that the gfn is in slot but faild to
  * translate it to pfn on host.
  */
-static inline bool is_error_pfn(pfn_t pfn)
+static inline bool is_error_pfn(kvm_pfn_t pfn)
 {
 	return !!(pfn & KVM_PFN_ERR_MASK);
 }
@@ -76,13 +76,13 @@ static inline bool is_error_pfn(pfn_t pfn)
  * translated to pfn - it is not in slot or failed to
  * translate it to pfn.
  */
-static inline bool is_error_noslot_pfn(pfn_t pfn)
+static inline bool is_error_noslot_pfn(kvm_pfn_t pfn)
 {
 	return !!(pfn & KVM_PFN_ERR_NOSLOT_MASK);
 }
 
 /* noslot pfn indicates that the gfn is not in slot. */
-static inline bool is_noslot_pfn(pfn_t pfn)
+static inline bool is_noslot_pfn(kvm_pfn_t pfn)
 {
 	return pfn == KVM_PFN_NOSLOT;
 }
@@ -614,19 +614,20 @@ void kvm_release_page_clean(struct page *page);
 void kvm_release_page_dirty(struct page *page);
 void kvm_set_page_accessed(struct page *page);
 
-pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn);
-pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
-pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
+kvm_pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn);
+kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn);
+kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
 		      bool *writable);
-pfn_t gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn);
-pfn_t gfn_to_pfn_memslot_atomic(struct kvm_memory_slot *slot, gfn_t gfn);
-pfn_t __gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn, bool atomic,
-			   bool *async, bool write_fault, bool *writable);
+kvm_pfn_t gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn);
+kvm_pfn_t gfn_to_pfn_memslot_atomic(struct kvm_memory_slot *slot, gfn_t gfn);
+kvm_pfn_t __gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn,
+			       bool atomic, bool *async, bool write_fault,
+			       bool *writable);
 
-void kvm_release_pfn_clean(pfn_t pfn);
-void kvm_set_pfn_dirty(pfn_t pfn);
-void kvm_set_pfn_accessed(pfn_t pfn);
-void kvm_get_pfn(pfn_t pfn);
+void kvm_release_pfn_clean(kvm_pfn_t pfn);
+void kvm_set_pfn_dirty(kvm_pfn_t pfn);
+void kvm_set_pfn_accessed(kvm_pfn_t pfn);
+void kvm_get_pfn(kvm_pfn_t pfn);
 
 int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
 			int len);
@@ -652,8 +653,8 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn);
 
 struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu);
 struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn);
-pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn);
-pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
+kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn);
+kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn);
 struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn);
 unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn);
 unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable);
@@ -836,7 +837,7 @@ void kvm_arch_sync_events(struct kvm *kvm);
 int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu);
 void kvm_vcpu_kick(struct kvm_vcpu *vcpu);
 
-bool kvm_is_reserved_pfn(pfn_t pfn);
+bool kvm_is_reserved_pfn(kvm_pfn_t pfn);
 
 struct kvm_irq_ack_notifier {
 	struct hlist_node link;
@@ -990,7 +991,7 @@ static inline gfn_t gpa_to_gfn(gpa_t gpa)
 	return (gfn_t)(gpa >> PAGE_SHIFT);
 }
 
-static inline hpa_t pfn_to_hpa(pfn_t pfn)
+static inline hpa_t pfn_to_hpa(kvm_pfn_t pfn)
 {
 	return (hpa_t)pfn << PAGE_SHIFT;
 }
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index 1b47a185c2f0..8bf259dae9f6 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -53,7 +53,7 @@ typedef unsigned long  hva_t;
 typedef u64            hpa_t;
 typedef u64            hfn_t;
 
-typedef hfn_t pfn_t;
+typedef hfn_t kvm_pfn_t;
 
 struct gfn_to_hva_cache {
 	u64 generation;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index be3cef12706c..fa2e296df24f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -111,7 +111,7 @@ static void hardware_disable_all(void);
 
 static void kvm_io_bus_destroy(struct kvm_io_bus *bus);
 
-static void kvm_release_pfn_dirty(pfn_t pfn);
+static void kvm_release_pfn_dirty(kvm_pfn_t pfn);
 static void mark_page_dirty_in_slot(struct kvm_memory_slot *memslot, gfn_t gfn);
 
 __visible bool kvm_rebooting;
@@ -119,7 +119,7 @@ EXPORT_SYMBOL_GPL(kvm_rebooting);
 
 static bool largepages_enabled = true;
 
-bool kvm_is_reserved_pfn(pfn_t pfn)
+bool kvm_is_reserved_pfn(kvm_pfn_t pfn)
 {
 	if (pfn_valid(pfn))
 		return PageReserved(pfn_to_page(pfn));
@@ -1299,7 +1299,7 @@ static inline int check_user_page_hwpoison(unsigned long addr)
  * true indicates success, otherwise false is returned.
  */
 static bool hva_to_pfn_fast(unsigned long addr, bool atomic, bool *async,
-			    bool write_fault, bool *writable, pfn_t *pfn)
+			    bool write_fault, bool *writable, kvm_pfn_t *pfn)
 {
 	struct page *page[1];
 	int npages;
@@ -1332,7 +1332,7 @@ static bool hva_to_pfn_fast(unsigned long addr, bool atomic, bool *async,
  * 1 indicates success, -errno is returned if error is detected.
  */
 static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault,
-			   bool *writable, pfn_t *pfn)
+			   bool *writable, kvm_pfn_t *pfn)
 {
 	struct page *page[1];
 	int npages = 0;
@@ -1396,11 +1396,11 @@ static bool vma_is_valid(struct vm_area_struct *vma, bool write_fault)
  * 2): @write_fault = false && @writable, @writable will tell the caller
  *     whether the mapping is writable.
  */
-static pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
+static kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
 			bool write_fault, bool *writable)
 {
 	struct vm_area_struct *vma;
-	pfn_t pfn = 0;
+	kvm_pfn_t pfn = 0;
 	int npages;
 
 	/* we can do it either atomically or asynchronously, not both */
@@ -1441,8 +1441,9 @@ exit:
 	return pfn;
 }
 
-pfn_t __gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn, bool atomic,
-			   bool *async, bool write_fault, bool *writable)
+kvm_pfn_t __gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn,
+			       bool atomic, bool *async, bool write_fault,
+			       bool *writable)
 {
 	unsigned long addr = __gfn_to_hva_many(slot, gfn, NULL, write_fault);
 
@@ -1463,7 +1464,7 @@ pfn_t __gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn, bool atomic,
 }
 EXPORT_SYMBOL_GPL(__gfn_to_pfn_memslot);
 
-pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
+kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
 		      bool *writable)
 {
 	return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, false, NULL,
@@ -1471,37 +1472,37 @@ pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn_prot);
 
-pfn_t gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn)
+kvm_pfn_t gfn_to_pfn_memslot(struct kvm_memory_slot *slot, gfn_t gfn)
 {
 	return __gfn_to_pfn_memslot(slot, gfn, false, NULL, true, NULL);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot);
 
-pfn_t gfn_to_pfn_memslot_atomic(struct kvm_memory_slot *slot, gfn_t gfn)
+kvm_pfn_t gfn_to_pfn_memslot_atomic(struct kvm_memory_slot *slot, gfn_t gfn)
 {
 	return __gfn_to_pfn_memslot(slot, gfn, true, NULL, true, NULL);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot_atomic);
 
-pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn)
+kvm_pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn)
 {
 	return gfn_to_pfn_memslot_atomic(gfn_to_memslot(kvm, gfn), gfn);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn_atomic);
 
-pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn)
+kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
 	return gfn_to_pfn_memslot_atomic(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_pfn_atomic);
 
-pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
+kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
 {
 	return gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn);
 }
 EXPORT_SYMBOL_GPL(gfn_to_pfn);
 
-pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn)
+kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
 	return gfn_to_pfn_memslot(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn);
 }
@@ -1524,7 +1525,7 @@ int gfn_to_page_many_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
 }
 EXPORT_SYMBOL_GPL(gfn_to_page_many_atomic);
 
-static struct page *kvm_pfn_to_page(pfn_t pfn)
+static struct page *kvm_pfn_to_page(kvm_pfn_t pfn)
 {
 	if (is_error_noslot_pfn(pfn))
 		return KVM_ERR_PTR_BAD_PAGE;
@@ -1539,7 +1540,7 @@ static struct page *kvm_pfn_to_page(pfn_t pfn)
 
 struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 {
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 
 	pfn = gfn_to_pfn(kvm, gfn);
 
@@ -1549,7 +1550,7 @@ EXPORT_SYMBOL_GPL(gfn_to_page);
 
 struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
-	pfn_t pfn;
+	kvm_pfn_t pfn;
 
 	pfn = kvm_vcpu_gfn_to_pfn(vcpu, gfn);
 
@@ -1565,7 +1566,7 @@ void kvm_release_page_clean(struct page *page)
 }
 EXPORT_SYMBOL_GPL(kvm_release_page_clean);
 
-void kvm_release_pfn_clean(pfn_t pfn)
+void kvm_release_pfn_clean(kvm_pfn_t pfn)
 {
 	if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn))
 		put_page(pfn_to_page(pfn));
@@ -1580,13 +1581,13 @@ void kvm_release_page_dirty(struct page *page)
 }
 EXPORT_SYMBOL_GPL(kvm_release_page_dirty);
 
-static void kvm_release_pfn_dirty(pfn_t pfn)
+static void kvm_release_pfn_dirty(kvm_pfn_t pfn)
 {
 	kvm_set_pfn_dirty(pfn);
 	kvm_release_pfn_clean(pfn);
 }
 
-void kvm_set_pfn_dirty(pfn_t pfn)
+void kvm_set_pfn_dirty(kvm_pfn_t pfn)
 {
 	if (!kvm_is_reserved_pfn(pfn)) {
 		struct page *page = pfn_to_page(pfn);
@@ -1597,14 +1598,14 @@ void kvm_set_pfn_dirty(pfn_t pfn)
 }
 EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);
 
-void kvm_set_pfn_accessed(pfn_t pfn)
+void kvm_set_pfn_accessed(kvm_pfn_t pfn)
 {
 	if (!kvm_is_reserved_pfn(pfn))
 		mark_page_accessed(pfn_to_page(pfn));
 }
 EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);
 
-void kvm_get_pfn(pfn_t pfn)
+void kvm_get_pfn(kvm_pfn_t pfn)
 {
 	if (!kvm_is_reserved_pfn(pfn))
 		get_page(pfn_to_page(pfn));

--
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[PATCH -mm 09/25] mm, dax, pmem: introduce pfn_t

[Dan Williams]

For the purpose of communicating the optional presence of a 'struct
page' for the pfn returned from ->direct_access(), introduce a type that
encapsulates a page-frame-number plus flags.  These flags contain the
historical "page_link" encoding for a scatterlist entry, but can also
denote "device memory".  Where "device memory" is a set of pfns that are
not part of the kernel's linear mapping by default, but are accessed via
the same memory controller as ram.

The motivation for this new type is large capacity persistent memory
that needs struct page entries in the 'memmap' to support 3rd party DMA
(i.e. O_DIRECT I/O with a persistent memory source/target).  However, we
also need it in support of maintaining a list of mapped inodes which
need to be unmapped at driver teardown or freeze_bdev() time.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Hansen <dave@sr71.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/powerpc/sysdev/axonram.c |    8 ++---
 drivers/block/brd.c           |    4 +-
 drivers/nvdimm/pmem.c         |   12 +++++--
 drivers/s390/block/dcssblk.c  |   10 ++----
 fs/dax.c                      |   10 ++++--
 include/linux/blkdev.h        |    4 +-
 include/linux/mm.h            |   66 +++++++++++++++++++++++++++++++++++++++++
 include/linux/pfn.h           |    9 ++++++
 8 files changed, 100 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/sysdev/axonram.c b/arch/powerpc/sysdev/axonram.c
index c713b349d967..801e22fa0b02 100644
--- a/arch/powerpc/sysdev/axonram.c
+++ b/arch/powerpc/sysdev/axonram.c
@@ -142,15 +142,13 @@ axon_ram_make_request(struct request_queue *queue, struct bio *bio)
  */
 static long
 axon_ram_direct_access(struct block_device *device, sector_t sector,
-		       void __pmem **kaddr, unsigned long *pfn)
+		       void __pmem **kaddr, pfn_t *pfn)
 {
 	struct axon_ram_bank *bank = device->bd_disk->private_data;
 	loff_t offset = (loff_t)sector << AXON_RAM_SECTOR_SHIFT;
-	void *addr = (void *)(bank->ph_addr + offset);
-
-	*kaddr = (void __pmem *)addr;
-	*pfn = virt_to_phys(addr) >> PAGE_SHIFT;
 
+	*kaddr = (void __pmem __force *) bank->io_addr + offset;
+	*pfn = phys_to_pfn_t(bank->ph_addr + offset, PFN_DEV);
 	return bank->size - offset;
 }
 
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index a5880f4ab40e..13e5c2fe9f7c 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -378,7 +378,7 @@ static int brd_rw_page(struct block_device *bdev, sector_t sector,
 
 #ifdef CONFIG_BLK_DEV_RAM_DAX
 static long brd_direct_access(struct block_device *bdev, sector_t sector,
-			void __pmem **kaddr, unsigned long *pfn)
+			void __pmem **kaddr, pfn_t *pfn)
 {
 	struct brd_device *brd = bdev->bd_disk->private_data;
 	struct page *page;
@@ -389,7 +389,7 @@ static long brd_direct_access(struct block_device *bdev, sector_t sector,
 	if (!page)
 		return -ENOSPC;
 	*kaddr = (void __pmem *)page_address(page);
-	*pfn = page_to_pfn(page);
+	*pfn = page_to_pfn_t(page);
 
 	return PAGE_SIZE;
 }
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 8ee79893d2f5..157951043b34 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -39,6 +39,7 @@ struct pmem_device {
 	phys_addr_t		phys_addr;
 	/* when non-zero this device is hosting a 'pfn' instance */
 	phys_addr_t		data_offset;
+	unsigned long		pfn_flags;
 	void __pmem		*virt_addr;
 	size_t			size;
 };
@@ -101,13 +102,13 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
 }
 
 static long pmem_direct_access(struct block_device *bdev, sector_t sector,
-		      void __pmem **kaddr, unsigned long *pfn)
+		      void __pmem **kaddr, pfn_t *pfn)
 {
 	struct pmem_device *pmem = bdev->bd_disk->private_data;
 	resource_size_t offset = sector * 512 + pmem->data_offset;
 
 	*kaddr = pmem->virt_addr + offset;
-	*pfn = (pmem->phys_addr + offset) >> PAGE_SHIFT;
+	*pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);
 
 	return pmem->size - offset;
 }
@@ -140,9 +141,11 @@ static struct pmem_device *pmem_alloc(struct device *dev,
 		return ERR_PTR(-EBUSY);
 	}
 
-	if (pmem_should_map_pages(dev))
+	pmem->pfn_flags = PFN_DEV;
+	if (pmem_should_map_pages(dev)) {
 		pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, res);
-	else
+		pmem->pfn_flags |= PFN_MAP;
+	} else
 		pmem->virt_addr = (void __pmem *) devm_memremap(dev,
 				pmem->phys_addr, pmem->size,
 				ARCH_MEMREMAP_PMEM);
@@ -353,6 +356,7 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
 	pmem = dev_get_drvdata(dev);
 	devm_memunmap(dev, (void __force *) pmem->virt_addr);
 	pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, &nsio->res);
+	pmem->pfn_flags |= PFN_MAP;
 	if (IS_ERR(pmem->virt_addr)) {
 		rc = PTR_ERR(pmem->virt_addr);
 		goto err;
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 94a8f4ab57bc..b50c5cb5601f 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -30,7 +30,7 @@ static void dcssblk_release(struct gendisk *disk, fmode_t mode);
 static blk_qc_t dcssblk_make_request(struct request_queue *q,
 						struct bio *bio);
 static long dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
-			 void __pmem **kaddr, unsigned long *pfn);
+			 void __pmem **kaddr, pfn_t *pfn);
 
 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
 
@@ -883,20 +883,18 @@ fail:
 
 static long
 dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
-			void __pmem **kaddr, unsigned long *pfn)
+			void __pmem **kaddr, pfn_t *pfn)
 {
 	struct dcssblk_dev_info *dev_info;
 	unsigned long offset, dev_sz;
-	void *addr;
 
 	dev_info = bdev->bd_disk->private_data;
 	if (!dev_info)
 		return -ENODEV;
 	dev_sz = dev_info->end - dev_info->start;
 	offset = secnum * 512;
-	addr = (void *) (dev_info->start + offset);
-	*pfn = virt_to_phys(addr) >> PAGE_SHIFT;
-	*kaddr = (void __pmem *) addr;
+	*kaddr = (void __pmem *) (dev_info->start + offset);
+	*pfn = phys_to_pfn_t(dev_info->start + offset, PFN_DEV);
 
 	return dev_sz - offset;
 }
diff --git a/fs/dax.c b/fs/dax.c
index 88e7b3bfef21..82897cf3cca0 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -362,7 +362,7 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
 	}
 	dax_unmap_atomic(bdev, &dax);
 
-	error = vm_insert_mixed(vma, vaddr, dax.pfn);
+	error = vm_insert_mixed(vma, vaddr, pfn_t_to_pfn(dax.pfn));
 
  out:
 	i_mmap_unlock_read(mapping);
@@ -667,7 +667,8 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 			result = VM_FAULT_SIGBUS;
 			goto out;
 		}
-		if ((length < PMD_SIZE) || (dax.pfn & PG_PMD_COLOUR)) {
+		if (length < PMD_SIZE
+				|| (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR)) {
 			dax_unmap_atomic(bdev, &dax);
 			goto fallback;
 		}
@@ -676,7 +677,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		 * TODO: teach vmf_insert_pfn_pmd() to support
 		 * 'pte_special' for pmds
 		 */
-		if (pfn_valid(dax.pfn)) {
+		if (pfn_t_has_page(dax.pfn)) {
 			dax_unmap_atomic(bdev, &dax);
 			goto fallback;
 		}
@@ -690,7 +691,8 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		}
 		dax_unmap_atomic(bdev, &dax);
 
-		result |= vmf_insert_pfn_pmd(vma, address, pmd, dax.pfn, write);
+		result |= vmf_insert_pfn_pmd(vma, address, pmd,
+				pfn_t_to_pfn(dax.pfn), write);
 	}
 
  out:
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ae94b18999ab..444002f98051 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1628,7 +1628,7 @@ struct blk_dax_ctl {
 	sector_t sector;
 	void __pmem *addr;
 	long size;
-	unsigned long pfn;
+	pfn_t pfn;
 };
 
 struct block_device_operations {
@@ -1638,7 +1638,7 @@ struct block_device_operations {
 	int (*ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
 	int (*compat_ioctl) (struct block_device *, fmode_t, unsigned, unsigned long);
 	long (*direct_access)(struct block_device *, sector_t, void __pmem **,
-			unsigned long *pfn);
+			pfn_t *);
 	unsigned int (*check_events) (struct gendisk *disk,
 				      unsigned int clearing);
 	/* ->media_changed() is DEPRECATED, use ->check_events() instead */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d988dd725b5c..9eab91af1e32 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -880,6 +880,72 @@ static inline void set_page_memcg(struct page *page, struct mem_cgroup *memcg)
 #endif
 
 /*
+ * PFN_FLAGS_MASK - mask of all the possible valid pfn_t flags
+ * PFN_SG_CHAIN - pfn is a pointer to the next scatterlist entry
+ * PFN_SG_LAST - pfn references a page and is the last scatterlist entry
+ * PFN_DEV - pfn is not covered by system memmap by default
+ * PFN_MAP - pfn has a dynamic page mapping established by a device driver
+ */
+#define PFN_FLAGS_MASK (((unsigned long) ~PAGE_MASK) \
+		<< (BITS_PER_LONG - PAGE_SHIFT))
+#define PFN_SG_CHAIN (1UL << (BITS_PER_LONG - 1))
+#define PFN_SG_LAST (1UL << (BITS_PER_LONG - 2))
+#define PFN_DEV (1UL << (BITS_PER_LONG - 3))
+#define PFN_MAP (1UL << (BITS_PER_LONG - 4))
+
+static inline pfn_t __pfn_to_pfn_t(unsigned long pfn, unsigned long flags)
+{
+	pfn_t pfn_t = { .val = pfn | (flags & PFN_FLAGS_MASK), };
+
+	return pfn_t;
+}
+
+/* a default pfn to pfn_t conversion assumes that @pfn is pfn_valid() */
+static inline pfn_t pfn_to_pfn_t(unsigned long pfn)
+{
+	return __pfn_to_pfn_t(pfn, 0);
+}
+
+static inline pfn_t phys_to_pfn_t(dma_addr_t addr, unsigned long flags)
+{
+	return __pfn_to_pfn_t(addr >> PAGE_SHIFT, flags);
+}
+
+static inline bool pfn_t_has_page(pfn_t pfn)
+{
+	return (pfn.val & PFN_MAP) == PFN_MAP || (pfn.val & PFN_DEV) == 0;
+}
+
+static inline unsigned long pfn_t_to_pfn(pfn_t pfn)
+{
+	return pfn.val & ~PFN_FLAGS_MASK;
+}
+
+static inline struct page *pfn_t_to_page(pfn_t pfn)
+{
+	if (pfn_t_has_page(pfn))
+		return pfn_to_page(pfn_t_to_pfn(pfn));
+	return NULL;
+}
+
+static inline dma_addr_t pfn_t_to_phys(pfn_t pfn)
+{
+	return PFN_PHYS(pfn_t_to_pfn(pfn));
+}
+
+static inline void *pfn_t_to_virt(pfn_t pfn)
+{
+	if (pfn_t_has_page(pfn))
+		return __va(pfn_t_to_phys(pfn));
+	return NULL;
+}
+
+static inline pfn_t page_to_pfn_t(struct page *page)
+{
+	return pfn_to_pfn_t(page_to_pfn(page));
+}
+
+/*
  * Some inline functions in vmstat.h depend on page_zone()
  */
 #include <linux/vmstat.h>
diff --git a/include/linux/pfn.h b/include/linux/pfn.h
index 97f3e88aead4..2d8e49711b63 100644
--- a/include/linux/pfn.h
+++ b/include/linux/pfn.h
@@ -3,6 +3,15 @@
 
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
+
+/*
+ * pfn_t: encapsulates a page-frame number that is optionally backed
+ * by memmap (struct page).  Whether a pfn_t has a 'struct page'
+ * backing is indicated by flags in the high bits of the value.
+ */
+typedef struct {
+	unsigned long val;
+} pfn_t;
 #endif
 
 #define PFN_ALIGN(x)	(((unsigned long)(x) + (PAGE_SIZE - 1)) & PAGE_MASK)

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[PATCH -mm 10/25] mm: introduce find_dev_pagemap()

[Dan Williams]

There are several scenarios where we need to retrieve and update
metadata associated with a given devm_memremap_pages() mapping, and the
only lookup key available is a pfn in the range:

1/ We want to augment vmemmap_populate() (called via arch_add_memory())
   to allocate memmap storage from pre-allocated pages reserved by the
   device driver.  At vmemmap_alloc_block_buf() time it grabs device pages
   rather than page allocator pages.  This is in support of
   devm_memremap_pages() mappings where the memmap is too large to fit in
   main memory (i.e. large persistent memory devices).

2/ Taking a reference against the mapping when inserting device pages
   into the address_space radix of a given inode.  This facilitates
   unmap_mapping_range() and truncate_inode_pages() operations when the
   driver is tearing down the mapping.

3/ get_user_pages() operations on ZONE_DEVICE memory require taking a
   reference against the mapping so that the driver teardown path can
   revoke and drain usage of device pages.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 include/linux/io.h |   15 ---------
 include/linux/mm.h |   33 ++++++++++++++++++++
 kernel/memremap.c  |   84 +++++++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 109 insertions(+), 23 deletions(-)

diff --git a/include/linux/io.h b/include/linux/io.h
index 72c35e0a41d1..32403b5716e5 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -90,21 +90,6 @@ void devm_memunmap(struct device *dev, void *addr);
 
 void *__devm_memremap_pages(struct device *dev, struct resource *res);
 
-#ifdef CONFIG_ZONE_DEVICE
-void *devm_memremap_pages(struct device *dev, struct resource *res);
-#else
-static inline void *devm_memremap_pages(struct device *dev, struct resource *res)
-{
-	/*
-	 * Fail attempts to call devm_memremap_pages() without
-	 * ZONE_DEVICE support enabled, this requires callers to fall
-	 * back to plain devm_memremap() based on config
-	 */
-	WARN_ON_ONCE(1);
-	return ERR_PTR(-ENXIO);
-}
-#endif
-
 /*
  * Some systems do not have legacy ISA devices.
  * /dev/port is not a valid interface on these systems.
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9eab91af1e32..5155a448a7f5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -670,6 +670,39 @@ static inline enum zone_type page_zonenum(const struct page *page)
 	return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;
 }
 
+struct resource;
+struct device;
+/**
+ * struct dev_pagemap - metadata for ZONE_DEVICE mappings
+ * @dev: host device of the mapping for debug
+ */
+struct dev_pagemap {
+	/* TODO: vmem_altmap and percpu_ref count */
+	struct device *dev;
+};
+
+#ifdef CONFIG_ZONE_DEVICE
+void *devm_memremap_pages(struct device *dev, struct resource *res);
+struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
+#else
+static inline void *devm_memremap_pages(struct device *dev,
+		struct resource *res)
+{
+	/*
+	 * Fail attempts to call devm_memremap_pages() without
+	 * ZONE_DEVICE support enabled, this requires callers to fall
+	 * back to plain devm_memremap() based on config
+	 */
+	WARN_ON_ONCE(1);
+	return ERR_PTR(-ENXIO);
+}
+
+static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
+{
+	return NULL;
+}
+#endif
+
 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
 #define SECTION_IN_PAGE_FLAGS
 #endif
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 7658d32c5c78..9698d82e5e48 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -10,6 +10,7 @@
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  */
+#include <linux/radix-tree.h>
 #include <linux/device.h>
 #include <linux/types.h>
 #include <linux/io.h>
@@ -148,22 +149,57 @@ void devm_memunmap(struct device *dev, void *addr)
 EXPORT_SYMBOL(devm_memunmap);
 
 #ifdef CONFIG_ZONE_DEVICE
+static DEFINE_MUTEX(pgmap_lock);
+static RADIX_TREE(pgmap_radix, GFP_KERNEL);
+#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)
+#define SECTION_SIZE (1UL << PA_SECTION_SHIFT)
+
 struct page_map {
 	struct resource res;
+	struct percpu_ref *ref;
+	struct dev_pagemap pgmap;
 };
 
-static void devm_memremap_pages_release(struct device *dev, void *res)
+static void pgmap_radix_release(struct resource *res)
+{
+	resource_size_t key;
+
+	mutex_lock(&pgmap_lock);
+	for (key = res->start; key <= res->end; key += SECTION_SIZE)
+		radix_tree_delete(&pgmap_radix, key >> PA_SECTION_SHIFT);
+	mutex_unlock(&pgmap_lock);
+}
+
+static void devm_memremap_pages_release(struct device *dev, void *data)
 {
-	struct page_map *page_map = res;
+	struct page_map *page_map = data;
+	struct resource *res = &page_map->res;
+	resource_size_t align_start, align_size;
+
+	pgmap_radix_release(res);
 
 	/* pages are dead and unused, undo the arch mapping */
-	arch_remove_memory(page_map->res.start, resource_size(&page_map->res));
+	align_start = res->start & ~(SECTION_SIZE - 1);
+	align_size = ALIGN(resource_size(res), SECTION_SIZE);
+	arch_remove_memory(align_start, align_size);
+}
+
+/* assumes rcu_read_lock() held at entry */
+struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
+{
+	struct page_map *page_map;
+
+	WARN_ON_ONCE(!rcu_read_lock_held());
+
+	page_map = radix_tree_lookup(&pgmap_radix, phys >> PA_SECTION_SHIFT);
+	return page_map ? &page_map->pgmap : NULL;
 }
 
 void *devm_memremap_pages(struct device *dev, struct resource *res)
 {
 	int is_ram = region_intersects(res->start, resource_size(res),
 			"System RAM");
+	resource_size_t key, align_start, align_size;
 	struct page_map *page_map;
 	int error, nid;
 
@@ -183,18 +219,50 @@ void *devm_memremap_pages(struct device *dev, struct resource *res)
 
 	memcpy(&page_map->res, res, sizeof(*res));
 
+	page_map->pgmap.dev = dev;
+	mutex_lock(&pgmap_lock);
+	error = 0;
+	for (key = res->start; key <= res->end; key += SECTION_SIZE) {
+		struct dev_pagemap *dup;
+
+		rcu_read_lock();
+		dup = find_dev_pagemap(key);
+		rcu_read_unlock();
+		if (dup) {
+			dev_err(dev, "%s: %pr collides with mapping for %s\n",
+					__func__, res, dev_name(dup->dev));
+			error = -EBUSY;
+			break;
+		}
+		error = radix_tree_insert(&pgmap_radix, key >> PA_SECTION_SHIFT,
+				page_map);
+		if (error) {
+			dev_err(dev, "%s: failed: %d\n", __func__, error);
+			break;
+		}
+	}
+	mutex_unlock(&pgmap_lock);
+	if (error)
+		goto err_radix;
+
 	nid = dev_to_node(dev);
 	if (nid < 0)
 		nid = numa_mem_id();
 
-	error = arch_add_memory(nid, res->start, resource_size(res), true);
-	if (error) {
-		devres_free(page_map);
-		return ERR_PTR(error);
-	}
+	align_start = res->start & ~(SECTION_SIZE - 1);
+	align_size = ALIGN(resource_size(res), SECTION_SIZE);
+	error = arch_add_memory(nid, align_start, align_size, true);
+	if (error)
+		goto err_add_memory;
 
 	devres_add(dev, page_map);
 	return __va(res->start);
+
+ err_add_memory:
+ err_radix:
+	pgmap_radix_release(res);
+	devres_free(page_map);
+	return ERR_PTR(error);
 }
 EXPORT_SYMBOL(devm_memremap_pages);
 #endif /* CONFIG_ZONE_DEVICE */

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[PATCH -mm 11/25] x86, mm: introduce vmem_altmap to augment vmemmap_populate()

[Dan Williams]

In support of providing struct page for large persistent memory
capacities, use struct vmem_altmap to change the default policy for
allocating memory for the memmap array.  The default vmemmap_populate()
allocates page table storage area from the page allocator.  Given
persistent memory capacities relative to DRAM it may not be feasible to
store the memmap in 'System Memory'.  Instead vmem_altmap represents
pre-allocated "device pages" to satisfy vmemmap_alloc_block_buf()
requests.

Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/m68k/include/asm/page_mm.h |    1 
 arch/m68k/include/asm/page_no.h |    1 
 arch/mn10300/include/asm/page.h |    1 
 arch/x86/mm/init_64.c           |   32 +++++++++++---
 drivers/nvdimm/pmem.c           |    6 ++-
 include/linux/memory_hotplug.h  |    3 +
 include/linux/mm.h              |   92 +++++++++++++++++++++++++++++++++++++--
 kernel/memremap.c               |   61 +++++++++++++++++++++++++-
 mm/memory_hotplug.c             |   66 ++++++++++++++++++++--------
 mm/page_alloc.c                 |   10 ++++
 mm/sparse-vmemmap.c             |   37 +++++++++++++++-
 mm/sparse.c                     |    8 ++-
 12 files changed, 277 insertions(+), 41 deletions(-)

diff --git a/arch/m68k/include/asm/page_mm.h b/arch/m68k/include/asm/page_mm.h
index e7a1946455a8..db4ddc9c7ace 100644
--- a/arch/m68k/include/asm/page_mm.h
+++ b/arch/m68k/include/asm/page_mm.h
@@ -122,6 +122,7 @@ static inline void *__va(unsigned long x)
  */
 #define virt_to_pfn(kaddr)	(__pa(kaddr) >> PAGE_SHIFT)
 #define pfn_to_virt(pfn)	__va((pfn) << PAGE_SHIFT)
+#define	__pfn_to_phys(pfn)	PFN_PHYS(pfn)
 
 extern int m68k_virt_to_node_shift;
 
diff --git a/arch/m68k/include/asm/page_no.h b/arch/m68k/include/asm/page_no.h
index fa7f32d9836b..0a72fb5bcb9d 100644
--- a/arch/m68k/include/asm/page_no.h
+++ b/arch/m68k/include/asm/page_no.h
@@ -21,6 +21,7 @@ extern unsigned long memory_end;
 
 #define virt_to_pfn(kaddr)	(__pa(kaddr) >> PAGE_SHIFT)
 #define pfn_to_virt(pfn)	__va((pfn) << PAGE_SHIFT)
+#define	__pfn_to_phys(pfn)	PFN_PHYS(pfn)
 
 #define virt_to_page(addr)	(mem_map + (((unsigned long)(addr)-PAGE_OFFSET) >> PAGE_SHIFT))
 #define page_to_virt(page)	__va(((((page) - mem_map) << PAGE_SHIFT) + PAGE_OFFSET))
diff --git a/arch/mn10300/include/asm/page.h b/arch/mn10300/include/asm/page.h
index 8288e124165b..3810a6f740fd 100644
--- a/arch/mn10300/include/asm/page.h
+++ b/arch/mn10300/include/asm/page.h
@@ -107,6 +107,7 @@ static inline int get_order(unsigned long size)
 #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
 #define pfn_to_page(pfn)	(mem_map + ((pfn) - __pfn_disp))
 #define page_to_pfn(page)	((unsigned long)((page) - mem_map) + __pfn_disp)
+#define __pfn_to_phys(pfn)	PFN_PHYS(pfn)
 
 #define pfn_valid(pfn)					\
 ({							\
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index ec081fe0ce2c..7e1f83c5a6d0 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -714,6 +714,12 @@ static void __meminit free_pagetable(struct page *page, int order)
 {
 	unsigned long magic;
 	unsigned int nr_pages = 1 << order;
+	struct vmem_altmap *altmap = to_vmem_altmap((unsigned long) page);
+
+	if (altmap) {
+		vmem_altmap_free(altmap, nr_pages);
+		return;
+	}
 
 	/* bootmem page has reserved flag */
 	if (PageReserved(page)) {
@@ -1018,13 +1024,19 @@ int __ref arch_remove_memory(u64 start, u64 size)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
+	struct page *page = pfn_to_page(start_pfn);
+	struct vmem_altmap *altmap;
 	struct zone *zone;
 	int ret;
 
-	zone = page_zone(pfn_to_page(start_pfn));
-	kernel_physical_mapping_remove(start, start + size);
+	/* With altmap the first mapped page is offset from @start */
+	altmap = to_vmem_altmap((unsigned long) page);
+	if (altmap)
+		page += vmem_altmap_offset(altmap);
+	zone = page_zone(page);
 	ret = __remove_pages(zone, start_pfn, nr_pages);
 	WARN_ON_ONCE(ret);
+	kernel_physical_mapping_remove(start, start + size);
 
 	return ret;
 }
@@ -1236,7 +1248,7 @@ static void __meminitdata *p_start, *p_end;
 static int __meminitdata node_start;
 
 static int __meminit vmemmap_populate_hugepages(unsigned long start,
-						unsigned long end, int node)
+		unsigned long end, int node, struct vmem_altmap *altmap)
 {
 	unsigned long addr;
 	unsigned long next;
@@ -1259,7 +1271,7 @@ static int __meminit vmemmap_populate_hugepages(unsigned long start,
 		if (pmd_none(*pmd)) {
 			void *p;
 
-			p = vmemmap_alloc_block_buf(PMD_SIZE, node);
+			p = __vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
 			if (p) {
 				pte_t entry;
 
@@ -1280,7 +1292,8 @@ static int __meminit vmemmap_populate_hugepages(unsigned long start,
 				addr_end = addr + PMD_SIZE;
 				p_end = p + PMD_SIZE;
 				continue;
-			}
+			} else if (altmap)
+				return -ENOMEM; /* no fallback */
 		} else if (pmd_large(*pmd)) {
 			vmemmap_verify((pte_t *)pmd, node, addr, next);
 			continue;
@@ -1294,11 +1307,16 @@ static int __meminit vmemmap_populate_hugepages(unsigned long start,
 
 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
 {
+	struct vmem_altmap *altmap = to_vmem_altmap(start);
 	int err;
 
 	if (cpu_has_pse)
-		err = vmemmap_populate_hugepages(start, end, node);
-	else
+		err = vmemmap_populate_hugepages(start, end, node, altmap);
+	else if (altmap) {
+		pr_err_once("%s: no cpu support for altmap allocations\n",
+				__func__);
+		err = -ENOMEM;
+	} else
 		err = vmemmap_populate_basepages(start, end, node);
 	if (!err)
 		sync_global_pgds(start, end - 1, 0);
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 157951043b34..34fa2f003602 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -143,7 +143,8 @@ static struct pmem_device *pmem_alloc(struct device *dev,
 
 	pmem->pfn_flags = PFN_DEV;
 	if (pmem_should_map_pages(dev)) {
-		pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, res);
+		pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, res,
+				NULL);
 		pmem->pfn_flags |= PFN_MAP;
 	} else
 		pmem->virt_addr = (void __pmem *) devm_memremap(dev,
@@ -355,7 +356,8 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
 	/* establish pfn range for lookup, and switch to direct map */
 	pmem = dev_get_drvdata(dev);
 	devm_memunmap(dev, (void __force *) pmem->virt_addr);
-	pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, &nsio->res);
+	pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, &nsio->res,
+			NULL);
 	pmem->pfn_flags |= PFN_MAP;
 	if (IS_ERR(pmem->virt_addr)) {
 		rc = PTR_ERR(pmem->virt_addr);
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 2ea574ff9714..43405992d027 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -275,7 +275,8 @@ extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
 extern bool is_memblock_offlined(struct memory_block *mem);
 extern void remove_memory(int nid, u64 start, u64 size);
 extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn);
-extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms);
+extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
+		unsigned long map_offset);
 extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
 					  unsigned long pnum);
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5155a448a7f5..c56f63cec895 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -673,20 +673,89 @@ static inline enum zone_type page_zonenum(const struct page *page)
 struct resource;
 struct device;
 /**
+ * struct vmem_altmap - pre-allocated storage for vmemmap_populate
+ * @base_pfn: base of the entire dev_pagemap mapping
+ * @reserve: pages mapped, but reserved for driver use (relative to @base)
+ * @free: free pages set aside in the mapping for memmap storage
+ * @align: pages reserved to meet allocation alignments
+ * @alloc: track pages consumed, private to vmemmap_populate()
+ */
+struct vmem_altmap {
+	const unsigned long base_pfn;
+	const unsigned long reserve;
+	unsigned long free;
+	unsigned long align;
+	unsigned long alloc;
+};
+
+static inline unsigned long vmem_altmap_nr_free(struct vmem_altmap *altmap)
+{
+	unsigned long allocated = altmap->alloc + altmap->align;
+
+	if (altmap->free > allocated)
+		return altmap->free - allocated;
+	return 0;
+}
+
+static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
+{
+	/* number of pfns from base where pfn_to_page() is valid */
+	return altmap->reserve + altmap->free;
+}
+
+static inline unsigned long vmem_altmap_next_pfn(struct vmem_altmap *altmap)
+{
+	return altmap->base_pfn + altmap->reserve + altmap->alloc
+		+ altmap->align;
+}
+
+/**
+ * vmem_altmap_alloc - allocate pages from the vmem_altmap reservation
+ * @altmap - reserved page pool for the allocation
+ * @nr_pfns - size (in pages) of the allocation
+ *
+ * Allocations are aligned to the size of the request
+ */
+static inline unsigned long vmem_altmap_alloc(struct vmem_altmap *altmap,
+		unsigned long nr_pfns)
+{
+	unsigned long pfn = vmem_altmap_next_pfn(altmap);
+	unsigned long nr_align;
+
+	nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
+	nr_align = ALIGN(pfn, nr_align) - pfn;
+
+	if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
+		return ULONG_MAX;
+	altmap->alloc += nr_pfns;
+	altmap->align += nr_align;
+	return pfn + nr_align;
+}
+
+static inline void vmem_altmap_free(struct vmem_altmap *altmap,
+		unsigned long nr_pfns)
+{
+	altmap->alloc -= nr_pfns;
+}
+
+/**
  * struct dev_pagemap - metadata for ZONE_DEVICE mappings
+ * @altmap: pre-allocated/reserved memory for vmemmap allocations
  * @dev: host device of the mapping for debug
  */
 struct dev_pagemap {
-	/* TODO: vmem_altmap and percpu_ref count */
+	struct vmem_altmap *altmap;
+	const struct resource *res;
 	struct device *dev;
 };
 
 #ifdef CONFIG_ZONE_DEVICE
-void *devm_memremap_pages(struct device *dev, struct resource *res);
+void *devm_memremap_pages(struct device *dev, struct resource *res,
+		struct vmem_altmap *altmap);
 struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
 #else
 static inline void *devm_memremap_pages(struct device *dev,
-		struct resource *res)
+		struct resource *res, struct vmem_altmap *altmap)
 {
 	/*
 	 * Fail attempts to call devm_memremap_pages() without
@@ -703,6 +772,15 @@ static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
 }
 #endif
 
+#if defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_ZONE_DEVICE)
+struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start);
+#else
+static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
+{
+	return NULL;
+}
+#endif
+
 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
 #define SECTION_IN_PAGE_FLAGS
 #endif
@@ -2307,7 +2385,13 @@ pud_t *vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node);
 pmd_t *vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node);
 pte_t *vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node);
 void *vmemmap_alloc_block(unsigned long size, int node);
-void *vmemmap_alloc_block_buf(unsigned long size, int node);
+void *__vmemmap_alloc_block_buf(unsigned long size, int node,
+		struct vmem_altmap *altmap);
+static inline void *vmemmap_alloc_block_buf(unsigned long size, int node)
+{
+	return __vmemmap_alloc_block_buf(size, node, NULL);
+}
+
 void vmemmap_verify(pte_t *, int, unsigned long, unsigned long);
 int vmemmap_populate_basepages(unsigned long start, unsigned long end,
 			       int node);
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 9698d82e5e48..1fb887227bcb 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -158,6 +158,7 @@ struct page_map {
 	struct resource res;
 	struct percpu_ref *ref;
 	struct dev_pagemap pgmap;
+	struct vmem_altmap altmap;
 };
 
 static void pgmap_radix_release(struct resource *res)
@@ -175,6 +176,7 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
 	struct page_map *page_map = data;
 	struct resource *res = &page_map->res;
 	resource_size_t align_start, align_size;
+	struct dev_pagemap *pgmap = &page_map->pgmap;
 
 	pgmap_radix_release(res);
 
@@ -182,6 +184,8 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
 	align_start = res->start & ~(SECTION_SIZE - 1);
 	align_size = ALIGN(resource_size(res), SECTION_SIZE);
 	arch_remove_memory(align_start, align_size);
+	dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
+			"%s: failed to free all reserved pages\n", __func__);
 }
 
 /* assumes rcu_read_lock() held at entry */
@@ -195,11 +199,23 @@ struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
 	return page_map ? &page_map->pgmap : NULL;
 }
 
-void *devm_memremap_pages(struct device *dev, struct resource *res)
+/**
+ * devm_memremap_pages - remap and provide memmap backing for the given resource
+ * @dev: hosting device for @res
+ * @res: "host memory" address range
+ * @altmap: optional descriptor for allocating the memmap from @res
+ *
+ * Note, the expectation is that @res is a host memory range that could
+ * feasibly be treated as a "System RAM" range, i.e. not a device mmio
+ * range, but this is not enforced.
+ */
+void *devm_memremap_pages(struct device *dev, struct resource *res,
+		struct vmem_altmap *altmap)
 {
 	int is_ram = region_intersects(res->start, resource_size(res),
 			"System RAM");
 	resource_size_t key, align_start, align_size;
+	struct dev_pagemap *pgmap;
 	struct page_map *page_map;
 	int error, nid;
 
@@ -212,14 +228,27 @@ void *devm_memremap_pages(struct device *dev, struct resource *res)
 	if (is_ram == REGION_INTERSECTS)
 		return __va(res->start);
 
+	if (altmap && !IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) {
+		dev_err(dev, "%s: altmap requires CONFIG_SPARSEMEM_VMEMMAP=y\n",
+				__func__);
+		return ERR_PTR(-ENXIO);
+	}
+
 	page_map = devres_alloc_node(devm_memremap_pages_release,
 			sizeof(*page_map), GFP_KERNEL, dev_to_node(dev));
 	if (!page_map)
 		return ERR_PTR(-ENOMEM);
+	pgmap = &page_map->pgmap;
 
 	memcpy(&page_map->res, res, sizeof(*res));
 
-	page_map->pgmap.dev = dev;
+	pgmap->dev = dev;
+	if (altmap) {
+		memcpy(&page_map->altmap, altmap, sizeof(*altmap));
+		pgmap->altmap = &page_map->altmap;
+	}
+	pgmap->res = &page_map->res;
+
 	mutex_lock(&pgmap_lock);
 	error = 0;
 	for (key = res->start; key <= res->end; key += SECTION_SIZE) {
@@ -266,3 +295,31 @@ void *devm_memremap_pages(struct device *dev, struct resource *res)
 }
 EXPORT_SYMBOL(devm_memremap_pages);
 #endif /* CONFIG_ZONE_DEVICE */
+
+#if defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_ZONE_DEVICE)
+struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
+{
+	/*
+	 * 'memmap_start' is the virtual address for the first "struct
+	 * page" in this range of the vmemmap array.  In the case of
+	 * CONFIG_SPARSE_VMEMMAP a page_to_pfn conversion is simple
+	 * pointer arithmetic, so we can perform this to_vmem_altmap()
+	 * conversion without concern for the initialization state of
+	 * the struct page fields.
+	 */
+	struct page *page = (struct page *) memmap_start;
+	struct dev_pagemap *pgmap;
+
+	/*
+	 * Uncoditionally retrieve a dev_pagemap associated with the
+	 * given physical address, this is only for use in the
+	 * arch_{add|remove}_memory() for setting up and tearing down
+	 * the memmap.
+	 */
+	rcu_read_lock();
+	pgmap = find_dev_pagemap(__pfn_to_phys(page_to_pfn(page)));
+	rcu_read_unlock();
+
+	return pgmap ? pgmap->altmap : NULL;
+}
+#endif /* defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_ZONE_DEVICE) */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 67d488ab495e..fa6a6db8cef6 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -505,10 +505,25 @@ int __ref __add_pages(int nid, struct zone *zone, unsigned long phys_start_pfn,
 	unsigned long i;
 	int err = 0;
 	int start_sec, end_sec;
+	struct vmem_altmap *altmap;
+
 	/* during initialize mem_map, align hot-added range to section */
 	start_sec = pfn_to_section_nr(phys_start_pfn);
 	end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
 
+	altmap = to_vmem_altmap((unsigned long) pfn_to_page(phys_start_pfn));
+	if (altmap) {
+		/*
+		 * Validate altmap is within bounds of the total request
+		 */
+		if (altmap->base_pfn != phys_start_pfn
+				|| vmem_altmap_offset(altmap) > nr_pages) {
+			pr_warn_once("memory add fail, invalid altmap\n");
+			return -EINVAL;
+		}
+		altmap->alloc = 0;
+	}
+
 	for (i = start_sec; i <= end_sec; i++) {
 		err = __add_section(nid, zone, section_nr_to_pfn(i));
 
@@ -730,7 +745,8 @@ static void __remove_zone(struct zone *zone, unsigned long start_pfn)
 	pgdat_resize_unlock(zone->zone_pgdat, &flags);
 }
 
-static int __remove_section(struct zone *zone, struct mem_section *ms)
+static int __remove_section(struct zone *zone, struct mem_section *ms,
+		unsigned long map_offset)
 {
 	unsigned long start_pfn;
 	int scn_nr;
@@ -747,7 +763,7 @@ static int __remove_section(struct zone *zone, struct mem_section *ms)
 	start_pfn = section_nr_to_pfn(scn_nr);
 	__remove_zone(zone, start_pfn);
 
-	sparse_remove_one_section(zone, ms);
+	sparse_remove_one_section(zone, ms, map_offset);
 	return 0;
 }
 
@@ -766,9 +782,32 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 		 unsigned long nr_pages)
 {
 	unsigned long i;
-	int sections_to_remove;
-	resource_size_t start, size;
-	int ret = 0;
+	unsigned long map_offset = 0;
+	int sections_to_remove, ret = 0;
+
+	/* In the ZONE_DEVICE case device driver owns the memory region */
+	if (is_dev_zone(zone)) {
+		struct page *page = pfn_to_page(phys_start_pfn);
+		struct vmem_altmap *altmap;
+
+		altmap = to_vmem_altmap((unsigned long) page);
+		if (altmap)
+			map_offset = vmem_altmap_offset(altmap);
+	} else {
+		resource_size_t start, size;
+
+		start = phys_start_pfn << PAGE_SHIFT;
+		size = nr_pages * PAGE_SIZE;
+
+		ret = release_mem_region_adjustable(&iomem_resource, start,
+					size);
+		if (ret) {
+			resource_size_t endres = start + size - 1;
+
+			pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
+					&start, &endres, ret);
+		}
+	}
 
 	/*
 	 * We can only remove entire sections
@@ -776,23 +815,12 @@ int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 	BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
 	BUG_ON(nr_pages % PAGES_PER_SECTION);
 
-	start = phys_start_pfn << PAGE_SHIFT;
-	size = nr_pages * PAGE_SIZE;
-
-	/* in the ZONE_DEVICE case device driver owns the memory region */
-	if (!is_dev_zone(zone))
-		ret = release_mem_region_adjustable(&iomem_resource, start, size);
-	if (ret) {
-		resource_size_t endres = start + size - 1;
-
-		pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
-				&start, &endres, ret);
-	}
-
 	sections_to_remove = nr_pages / PAGES_PER_SECTION;
 	for (i = 0; i < sections_to_remove; i++) {
 		unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
-		ret = __remove_section(zone, __pfn_to_section(pfn));
+
+		ret = __remove_section(zone, __pfn_to_section(pfn), map_offset);
+		map_offset = 0;
 		if (ret)
 			break;
 	}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d6d7c97c0b28..05bf3f1bf562 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4495,8 +4495,9 @@ static inline unsigned long wait_table_bits(unsigned long size)
 void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 		unsigned long start_pfn, enum memmap_context context)
 {
-	pg_data_t *pgdat = NODE_DATA(nid);
+	struct vmem_altmap *altmap = to_vmem_altmap(__pfn_to_phys(start_pfn));
 	unsigned long end_pfn = start_pfn + size;
+	pg_data_t *pgdat = NODE_DATA(nid);
 	unsigned long pfn;
 	struct zone *z;
 	unsigned long nr_initialised = 0;
@@ -4504,6 +4505,13 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 	if (highest_memmap_pfn < end_pfn - 1)
 		highest_memmap_pfn = end_pfn - 1;
 
+	/*
+	 * Honor reservation requested by the driver for this ZONE_DEVICE
+	 * memory
+	 */
+	if (altmap && start_pfn == altmap->base_pfn)
+		start_pfn += altmap->reserve;
+
 	z = &pgdat->node_zones[zone];
 	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
 		/*
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 4cba9c2783a1..e6b17a05e189 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -70,7 +70,7 @@ void * __meminit vmemmap_alloc_block(unsigned long size, int node)
 }
 
 /* need to make sure size is all the same during early stage */
-void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
+static void * __meminit alloc_block_buf(unsigned long size, int node)
 {
 	void *ptr;
 
@@ -87,6 +87,39 @@ void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
 	return ptr;
 }
 
+static void * __meminit altmap_alloc_block_buf(unsigned long size,
+		struct vmem_altmap *altmap)
+{
+	unsigned long pfn, nr_pfns;
+	void *ptr;
+
+	if (size & ~PAGE_MASK) {
+		pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
+				__func__, size);
+		return NULL;
+	}
+
+	nr_pfns = size >> PAGE_SHIFT;
+	pfn = vmem_altmap_alloc(altmap, nr_pfns);
+	if (pfn < ULONG_MAX)
+		ptr = __va(__pfn_to_phys(pfn));
+	else
+		ptr = NULL;
+	pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
+			__func__, pfn, altmap->alloc, altmap->align, nr_pfns);
+
+	return ptr;
+}
+
+/* need to make sure size is all the same during early stage */
+void * __meminit __vmemmap_alloc_block_buf(unsigned long size, int node,
+		struct vmem_altmap *altmap)
+{
+	if (altmap)
+		return altmap_alloc_block_buf(size, altmap);
+	return alloc_block_buf(size, node);
+}
+
 void __meminit vmemmap_verify(pte_t *pte, int node,
 				unsigned long start, unsigned long end)
 {
@@ -103,7 +136,7 @@ pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
 	pte_t *pte = pte_offset_kernel(pmd, addr);
 	if (pte_none(*pte)) {
 		pte_t entry;
-		void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
+		void *p = alloc_block_buf(PAGE_SIZE, node);
 		if (!p)
 			return NULL;
 		entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
diff --git a/mm/sparse.c b/mm/sparse.c
index d1b48b691ac8..3717ceed4177 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -748,7 +748,7 @@ static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
 	if (!memmap)
 		return;
 
-	for (i = 0; i < PAGES_PER_SECTION; i++) {
+	for (i = 0; i < nr_pages; i++) {
 		if (PageHWPoison(&memmap[i])) {
 			atomic_long_sub(1, &num_poisoned_pages);
 			ClearPageHWPoison(&memmap[i]);
@@ -788,7 +788,8 @@ static void free_section_usemap(struct page *memmap, unsigned long *usemap)
 		free_map_bootmem(memmap);
 }
 
-void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
+void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
+		unsigned long map_offset)
 {
 	struct page *memmap = NULL;
 	unsigned long *usemap = NULL, flags;
@@ -804,7 +805,8 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 	}
 	pgdat_resize_unlock(pgdat, &flags);
 
-	clear_hwpoisoned_pages(memmap, PAGES_PER_SECTION);
+	clear_hwpoisoned_pages(memmap + map_offset,
+			PAGES_PER_SECTION - map_offset);
 	free_section_usemap(memmap, usemap);
 }
 #endif /* CONFIG_MEMORY_HOTREMOVE */

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[PATCH -mm 12/25] libnvdimm, pfn, pmem: allocate memmap array in persistent memory

[Dan Williams]

Use the new vmem_altmap capability to enable the pmem driver to arrange
for a struct page memmap to be established in persistent memory.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/ia64/include/asm/page.h |    1 +
 drivers/nvdimm/pfn_devs.c    |    3 +--
 drivers/nvdimm/pmem.c        |   19 +++++++++++++++++--
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/arch/ia64/include/asm/page.h b/arch/ia64/include/asm/page.h
index ec48bb9f95e1..e8c486ef0d76 100644
--- a/arch/ia64/include/asm/page.h
+++ b/arch/ia64/include/asm/page.h
@@ -105,6 +105,7 @@ extern struct page *vmem_map;
 #ifdef CONFIG_DISCONTIGMEM
 # define page_to_pfn(page)	((unsigned long) (page - vmem_map))
 # define pfn_to_page(pfn)	(vmem_map + (pfn))
+# define __pfn_to_phys(pfn)	PFN_PHYS(pfn)
 #else
 # include <asm-generic/memory_model.h>
 #endif
diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 71805a1aa0f3..a642cfacee07 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -83,8 +83,7 @@ static ssize_t mode_store(struct device *dev,
 
 		if (strncmp(buf, "pmem\n", n) == 0
 				|| strncmp(buf, "pmem", n) == 0) {
-			/* TODO: allocate from PMEM support */
-			rc = -ENOTTY;
+			nd_pfn->mode = PFN_MODE_PMEM;
 		} else if (strncmp(buf, "ram\n", n) == 0
 				|| strncmp(buf, "ram", n) == 0)
 			nd_pfn->mode = PFN_MODE_RAM;
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 34fa2f003602..1d884318c67b 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -315,12 +315,16 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
 	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
 	struct nd_pfn *nd_pfn = to_nd_pfn(ndns->claim);
 	struct device *dev = &nd_pfn->dev;
-	struct vmem_altmap *altmap;
 	struct nd_region *nd_region;
+	struct vmem_altmap *altmap;
 	struct nd_pfn_sb *pfn_sb;
 	struct pmem_device *pmem;
 	phys_addr_t offset;
 	int rc;
+	struct vmem_altmap __altmap = {
+		.base_pfn = __phys_to_pfn(nsio->res.start),
+		.reserve = __phys_to_pfn(SZ_8K),
+	};
 
 	if (!nd_pfn->uuid || !nd_pfn->ndns)
 		return -ENODEV;
@@ -348,6 +352,17 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
 			return -EINVAL;
 		nd_pfn->npfns = le64_to_cpu(pfn_sb->npfns);
 		altmap = NULL;
+	} else if (nd_pfn->mode == PFN_MODE_PMEM) {
+		nd_pfn->npfns = (resource_size(&nsio->res) - offset)
+			/ PAGE_SIZE;
+		if (le64_to_cpu(nd_pfn->pfn_sb->npfns) > nd_pfn->npfns)
+			dev_info(&nd_pfn->dev,
+					"number of pfns truncated from %lld to %ld\n",
+					le64_to_cpu(nd_pfn->pfn_sb->npfns),
+					nd_pfn->npfns);
+		altmap = & __altmap;
+		altmap->free = __phys_to_pfn(offset - SZ_8K);
+		altmap->alloc = 0;
 	} else {
 		rc = -ENXIO;
 		goto err;
@@ -357,7 +372,7 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
 	pmem = dev_get_drvdata(dev);
 	devm_memunmap(dev, (void __force *) pmem->virt_addr);
 	pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, &nsio->res,
-			NULL);
+			altmap);
 	pmem->pfn_flags |= PFN_MAP;
 	if (IS_ERR(pmem->virt_addr)) {
 		rc = PTR_ERR(pmem->virt_addr);

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[PATCH -mm 13/25] avr32: convert to asm-generic/memory_model.h

[Dan Williams]

Switch avr32/include/asm/page.h to use the common defintions for
pfn_to_page(), page_to_pfn(), and ARCH_PFN_OFFSET.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/avr32/include/asm/page.h |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/avr32/include/asm/page.h b/arch/avr32/include/asm/page.h
index f805d1cb11bc..c5d2a3e2c62f 100644
--- a/arch/avr32/include/asm/page.h
+++ b/arch/avr32/include/asm/page.h
@@ -83,11 +83,9 @@ static inline int get_order(unsigned long size)
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
 
-#define PHYS_PFN_OFFSET		(CONFIG_PHYS_OFFSET >> PAGE_SHIFT)
+#define ARCH_PFN_OFFSET		(CONFIG_PHYS_OFFSET >> PAGE_SHIFT)
 
-#define pfn_to_page(pfn)	(mem_map + ((pfn) - PHYS_PFN_OFFSET))
-#define page_to_pfn(page)	((unsigned long)((page) - mem_map) + PHYS_PFN_OFFSET)
-#define pfn_valid(pfn)		((pfn) >= PHYS_PFN_OFFSET && (pfn) < (PHYS_PFN_OFFSET + max_mapnr))
+#define pfn_valid(pfn)		((pfn) >= ARCH_PFN_OFFSET && (pfn) < (ARCH_PFN_OFFSET + max_mapnr))
 #endif /* CONFIG_NEED_MULTIPLE_NODES */
 
 #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
@@ -101,4 +99,6 @@ static inline int get_order(unsigned long size)
  */
 #define HIGHMEM_START		0x20000000UL
 
+#include <asm-generic/memory_model.h>
+
 #endif /* __ASM_AVR32_PAGE_H */

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[PATCH -mm 14/25] hugetlb: fix compile error on tile

[Dan Williams]

Inlude asm/pgtable.h to get the definition for pud_t to fix:

include/linux/hugetlb.h:203:29: error: unknown type name 'pud_t'

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 include/linux/hugetlb.h |    1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 204c7f56f35a..2b61bf566161 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -8,6 +8,7 @@
 #include <linux/cgroup.h>
 #include <linux/list.h>
 #include <linux/kref.h>
+#include <asm/pgtable.h>
 
 struct ctl_table;
 struct user_struct;

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[PATCH -mm 15/25] frv: fix compiler warning from definition of __pmd()

[Dan Williams]

Take into account that the pmd_t type is a array inside a struct, so it
needs two levels of brackets to initialize.  Otherwise, a usage of __pmd
generates a warning:

include/linux/mm.h:986:2: warning: missing braces around initializer [-Wmissing-braces]

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/frv/include/asm/page.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/frv/include/asm/page.h b/arch/frv/include/asm/page.h
index 52ace96a4f55..ec5eebce4fb3 100644
--- a/arch/frv/include/asm/page.h
+++ b/arch/frv/include/asm/page.h
@@ -31,7 +31,7 @@ typedef struct page *pgtable_t;
 #define pgprot_val(x)	((x).pgprot)
 
 #define __pte(x)	((pte_t) { (x) } )
-#define __pmd(x)	((pmd_t) { (x) } )
+#define __pmd(x)	((pmd_t) { { (x) } } )
 #define __pud(x)	((pud_t) { (x) } )
 #define __pgd(x)	((pgd_t) { (x) } )
 #define __pgprot(x)	((pgprot_t) { (x) } )

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[PATCH -mm 16/25] x86, mm: introduce _PAGE_DEVMAP

[Dan Williams]

_PAGE_DEVMAP is a hardware-unused pte bit that will later be used in the
get_user_pages() path to identify pfns backed by the dynamic allocation
established by devm_memremap_pages.  Upon seeing that bit the gup path
will lookup and pin the allocation while the pages are in use.

Since the _PAGE_DEVMAP bit is > 32 it requires workarounds in
pmd_flags() to allow it to build the realmode boot code as well as
satsify pmd_bad();

In file included from ./arch/x86/include/asm/boot.h:5:0,
                 from arch/x86/realmode/rm/../../boot/boot.h:26,
                 from arch/x86/realmode/rm/../../boot/regs.c:19,
                 from arch/x86/realmode/rm/regs.c:1:
./arch/x86/include/asm/pgtable_types.h: In function ‘pmd_pfn_mask’:
./arch/x86/include/asm/pgtable_types.h:310:3: warning: left shift count >= width of type
   return mask ^ _PAGE_DEVMAP;

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/x86/include/asm/page_types.h    |    3 ++-
 arch/x86/include/asm/pgtable_types.h |    7 ++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h
index c5b7fb2774d0..160a19786806 100644
--- a/arch/x86/include/asm/page_types.h
+++ b/arch/x86/include/asm/page_types.h
@@ -15,7 +15,8 @@
 /* Cast PAGE_MASK to a signed type so that it is sign-extended if
    virtual addresses are 32-bits but physical addresses are larger
    (ie, 32-bit PAE). */
-#define PHYSICAL_PAGE_MASK	(((signed long)PAGE_MASK) & __PHYSICAL_MASK)
+#define PHYSICAL_PAGE_MASK	(((signed long)PAGE_MASK) & (__PHYSICAL_MASK \
+						& ~_PAGE_DEVMAP))
 
 #define PMD_PAGE_SIZE		(_AC(1, UL) << PMD_SHIFT)
 #define PMD_PAGE_MASK		(~(PMD_PAGE_SIZE-1))
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 116fc4ee586f..08475aab4c66 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -24,7 +24,9 @@
 #define _PAGE_BIT_CPA_TEST	_PAGE_BIT_SOFTW1
 #define _PAGE_BIT_HIDDEN	_PAGE_BIT_SOFTW3 /* hidden by kmemcheck */
 #define _PAGE_BIT_SOFT_DIRTY	_PAGE_BIT_SOFTW3 /* software dirty tracking */
-#define _PAGE_BIT_NX           63       /* No execute: only valid after cpuid check */
+#define _PAGE_BIT_SOFTW4	58	/* available for programmer */
+#define _PAGE_BIT_DEVMAP		_PAGE_BIT_SOFTW4
+#define _PAGE_BIT_NX		63	/* No execute: only valid after cpuid check */
 
 /* If _PAGE_BIT_PRESENT is clear, we use these: */
 /* - if the user mapped it with PROT_NONE; pte_present gives true */
@@ -83,8 +85,11 @@
 
 #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
 #define _PAGE_NX	(_AT(pteval_t, 1) << _PAGE_BIT_NX)
+#define _PAGE_DEVMAP	(_AT(u64, 1) << _PAGE_BIT_DEVMAP)
+#define __HAVE_ARCH_PTE_DEVMAP
 #else
 #define _PAGE_NX	(_AT(pteval_t, 0))
+#define _PAGE_DEVMAP	(_AT(pteval_t, 0))
 #endif
 
 #define _PAGE_PROTNONE	(_AT(pteval_t, 1) << _PAGE_BIT_PROTNONE)

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[PATCH -mm 16/25] x86, mm: introduce _PAGE_DEVMAP

[Dan Williams]

_PAGE_DEVMAP is a hardware-unused pte bit that will later be used in the
get_user_pages() path to identify pfns backed by the dynamic allocation
established by devm_memremap_pages.  Upon seeing that bit the gup path
will lookup and pin the allocation while the pages are in use.

Since the _PAGE_DEVMAP bit is > 32 it requires workarounds in
pmd_flags() to allow it to build the realmode boot code as well as
satsify pmd_bad();

In file included from ./arch/x86/include/asm/boot.h:5:0,
                 from arch/x86/realmode/rm/../../boot/boot.h:26,
                 from arch/x86/realmode/rm/../../boot/regs.c:19,
                 from arch/x86/realmode/rm/regs.c:1:
./arch/x86/include/asm/pgtable_types.h: In function a??pmd_pfn_maska??:
./arch/x86/include/asm/pgtable_types.h:310:3: warning: left shift count >= width of type
   return mask ^ _PAGE_DEVMAP;

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/x86/include/asm/page_types.h    |    3 ++-
 arch/x86/include/asm/pgtable_types.h |    7 ++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h
index c5b7fb2774d0..160a19786806 100644
--- a/arch/x86/include/asm/page_types.h
+++ b/arch/x86/include/asm/page_types.h
@@ -15,7 +15,8 @@
 /* Cast PAGE_MASK to a signed type so that it is sign-extended if
    virtual addresses are 32-bits but physical addresses are larger
    (ie, 32-bit PAE). */
-#define PHYSICAL_PAGE_MASK	(((signed long)PAGE_MASK) & __PHYSICAL_MASK)
+#define PHYSICAL_PAGE_MASK	(((signed long)PAGE_MASK) & (__PHYSICAL_MASK \
+						& ~_PAGE_DEVMAP))
 
 #define PMD_PAGE_SIZE		(_AC(1, UL) << PMD_SHIFT)
 #define PMD_PAGE_MASK		(~(PMD_PAGE_SIZE-1))
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 116fc4ee586f..08475aab4c66 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -24,7 +24,9 @@
 #define _PAGE_BIT_CPA_TEST	_PAGE_BIT_SOFTW1
 #define _PAGE_BIT_HIDDEN	_PAGE_BIT_SOFTW3 /* hidden by kmemcheck */
 #define _PAGE_BIT_SOFT_DIRTY	_PAGE_BIT_SOFTW3 /* software dirty tracking */
-#define _PAGE_BIT_NX           63       /* No execute: only valid after cpuid check */
+#define _PAGE_BIT_SOFTW4	58	/* available for programmer */
+#define _PAGE_BIT_DEVMAP		_PAGE_BIT_SOFTW4
+#define _PAGE_BIT_NX		63	/* No execute: only valid after cpuid check */
 
 /* If _PAGE_BIT_PRESENT is clear, we use these: */
 /* - if the user mapped it with PROT_NONE; pte_present gives true */
@@ -83,8 +85,11 @@
 
 #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
 #define _PAGE_NX	(_AT(pteval_t, 1) << _PAGE_BIT_NX)
+#define _PAGE_DEVMAP	(_AT(u64, 1) << _PAGE_BIT_DEVMAP)
+#define __HAVE_ARCH_PTE_DEVMAP
 #else
 #define _PAGE_NX	(_AT(pteval_t, 0))
+#define _PAGE_DEVMAP	(_AT(pteval_t, 0))
 #endif
 
 #define _PAGE_PROTNONE	(_AT(pteval_t, 1) << _PAGE_BIT_PROTNONE)

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[PATCH -mm 17/25] mm, dax, gpu: convert vm_insert_mixed to pfn_t

[Dan Williams]

Convert the raw unsigned long 'pfn' argument to pfn_t for the purpose
of evaluating the PFN_MAP and PFN_DEV flags.  When both are set it
triggers _PAGE_DEVMAP to be set in the resulting pte.

There are no functional changes to the gpu drivers as a result of this
conversion.

This uncovered several architectures with no local definition for
pfn_pte(), in response pfn_t_pte() is only defined when an arch opts-in
by "#define pfn_pte pfn_pte".

Cc: Dave Hansen <dave@sr71.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/alpha/include/asm/pgtable.h        |    1 +
 arch/parisc/include/asm/pgtable.h       |    1 +
 arch/powerpc/include/asm/pgtable.h      |    1 +
 arch/sparc/include/asm/pgtable_64.h     |    1 +
 arch/tile/include/asm/pgtable.h         |    1 +
 arch/um/include/asm/pgtable-3level.h    |    1 +
 arch/x86/include/asm/pgtable.h          |   12 +++++++++++
 drivers/gpu/drm/exynos/exynos_drm_gem.c |    3 ++-
 drivers/gpu/drm/gma500/framebuffer.c    |    3 ++-
 drivers/gpu/drm/msm/msm_gem.c           |    3 ++-
 drivers/gpu/drm/omapdrm/omap_gem.c      |    6 ++++--
 drivers/gpu/drm/ttm/ttm_bo_vm.c         |    3 ++-
 fs/dax.c                                |    2 +-
 include/linux/mm.h                      |   33 ++++++++++++++++++++++++++++++-
 mm/memory.c                             |   15 ++++++++------
 15 files changed, 72 insertions(+), 14 deletions(-)

diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h
index a9a119592372..a54050fe867e 100644
--- a/arch/alpha/include/asm/pgtable.h
+++ b/arch/alpha/include/asm/pgtable.h
@@ -216,6 +216,7 @@ extern unsigned long __zero_page(void);
 })
 #endif
 
+#define pfn_pte pfn_pte
 extern inline pte_t pfn_pte(unsigned long physpfn, pgprot_t pgprot)
 { pte_t pte; pte_val(pte) = (PHYS_TWIDDLE(physpfn) << 32) | pgprot_val(pgprot); return pte; }
 
diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm/pgtable.h
index d8534f95915a..14fb76ccefe7 100644
--- a/arch/parisc/include/asm/pgtable.h
+++ b/arch/parisc/include/asm/pgtable.h
@@ -394,6 +394,7 @@ static inline pte_t pte_mkspecial(pte_t pte)	{ return pte; }
 
 #define mk_pte(page, pgprot)	pfn_pte(page_to_pfn(page), (pgprot))
 
+#define pfn_pte pfn_pte
 static inline pte_t pfn_pte(unsigned long pfn, pgprot_t pgprot)
 {
 	pte_t pte;
diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
index b64b4212b71f..38563174acef 100644
--- a/arch/powerpc/include/asm/pgtable.h
+++ b/arch/powerpc/include/asm/pgtable.h
@@ -67,6 +67,7 @@ static inline int pte_present(pte_t pte)
  * Even if PTEs can be unsigned long long, a PFN is always an unsigned
  * long for now.
  */
+#define pfn_pte pfn_pte
 static inline pte_t pfn_pte(unsigned long pfn, pgprot_t pgprot) {
 	return __pte(((pte_basic_t)(pfn) << PTE_RPN_SHIFT) |
 		     pgprot_val(pgprot)); }
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index f5bfcd66aeb5..e1a49f02b5b4 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -234,6 +234,7 @@ extern struct page *mem_map_zero;
  * the first physical page in the machine is at some huge physical address,
  * such as 4GB.   This is common on a partitioned E10000, for example.
  */
+#define pfn_pte pfn_pte
 static inline pte_t pfn_pte(unsigned long pfn, pgprot_t prot)
 {
 	unsigned long paddr = pfn << PAGE_SHIFT;
diff --git a/arch/tile/include/asm/pgtable.h b/arch/tile/include/asm/pgtable.h
index 96cecf55522e..983f1ed37d62 100644
--- a/arch/tile/include/asm/pgtable.h
+++ b/arch/tile/include/asm/pgtable.h
@@ -275,6 +275,7 @@ static inline unsigned long pte_pfn(pte_t pte)
 extern pgprot_t set_remote_cache_cpu(pgprot_t prot, int cpu);
 extern int get_remote_cache_cpu(pgprot_t prot);
 
+#define pfn_pte pfn_pte
 static inline pte_t pfn_pte(unsigned long pfn, pgprot_t prot)
 {
 	return hv_pte_set_pa(prot, PFN_PHYS(pfn));
diff --git a/arch/um/include/asm/pgtable-3level.h b/arch/um/include/asm/pgtable-3level.h
index bae8523a162f..b7b51db14c2f 100644
--- a/arch/um/include/asm/pgtable-3level.h
+++ b/arch/um/include/asm/pgtable-3level.h
@@ -98,6 +98,7 @@ static inline unsigned long pte_pfn(pte_t pte)
 	return phys_to_pfn(pte_val(pte));
 }
 
+#define pfn_pte pfn_pte
 static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
 {
 	pte_t pte;
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 61e706c9f710..d06baa865a50 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -247,6 +247,11 @@ static inline pte_t pte_mkspecial(pte_t pte)
 	return pte_set_flags(pte, _PAGE_SPECIAL);
 }
 
+static inline pte_t pte_mkdevmap(pte_t pte)
+{
+	return pte_set_flags(pte, _PAGE_SPECIAL|_PAGE_DEVMAP);
+}
+
 static inline pmd_t pmd_set_flags(pmd_t pmd, pmdval_t set)
 {
 	pmdval_t v = native_pmd_val(pmd);
@@ -343,6 +348,7 @@ static inline pgprotval_t massage_pgprot(pgprot_t pgprot)
 	return protval;
 }
 
+#define pfn_pte pfn_pte
 static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
 {
 	return __pte(((phys_addr_t)page_nr << PAGE_SHIFT) |
@@ -457,6 +463,12 @@ static inline int pte_present(pte_t a)
 	return pte_flags(a) & (_PAGE_PRESENT | _PAGE_PROTNONE);
 }
 
+#define pte_devmap pte_devmap
+static inline int pte_devmap(pte_t a)
+{
+	return (pte_flags(a) & _PAGE_DEVMAP) == _PAGE_DEVMAP;
+}
+
 #define pte_accessible pte_accessible
 static inline bool pte_accessible(struct mm_struct *mm, pte_t a)
 {
diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 252eb301470c..973df42fc1eb 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -490,7 +490,8 @@ int exynos_drm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	}
 
 	pfn = page_to_pfn(exynos_gem->pages[page_offset]);
-	ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
+	ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address,
+			pfn_to_pfn_t(pfn, PFN_DEV));
 
 out:
 	switch (ret) {
diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c
index ee95c03a8c54..ecb5b1f66f87 100644
--- a/drivers/gpu/drm/gma500/framebuffer.c
+++ b/drivers/gpu/drm/gma500/framebuffer.c
@@ -132,7 +132,8 @@ static int psbfb_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	for (i = 0; i < page_num; i++) {
 		pfn = (phys_addr >> PAGE_SHIFT);
 
-		ret = vm_insert_mixed(vma, address, pfn);
+		ret = vm_insert_mixed(vma, address,
+				__pfn_to_pfn_t(pfn, PFN_DEV));
 		if (unlikely((ret == -EBUSY) || (ret != 0 && i > 0)))
 			break;
 		else if (unlikely(ret != 0)) {
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index c76cc853b08a..0f4ed5bfda83 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -222,7 +222,8 @@ int msm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	VERB("Inserting %p pfn %lx, pa %lx", vmf->virtual_address,
 			pfn, pfn << PAGE_SHIFT);
 
-	ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
+	ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address,
+			pfn_to_pfn_t(pfn, PFN_DEV));
 
 out_unlock:
 	mutex_unlock(&dev->struct_mutex);
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index 7ed08fdc4c42..910cb276a7ea 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -385,7 +385,8 @@ static int fault_1d(struct drm_gem_object *obj,
 	VERB("Inserting %p pfn %lx, pa %lx", vmf->virtual_address,
 			pfn, pfn << PAGE_SHIFT);
 
-	return vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
+	return vm_insert_mixed(vma, (unsigned long)vmf->virtual_address,
+			pfn_to_pfn_t(pfn, PFN_DEV));
 }
 
 /* Special handling for the case of faulting in 2d tiled buffers */
@@ -478,7 +479,8 @@ static int fault_2d(struct drm_gem_object *obj,
 			pfn, pfn << PAGE_SHIFT);
 
 	for (i = n; i > 0; i--) {
-		vm_insert_mixed(vma, (unsigned long)vaddr, pfn);
+		vm_insert_mixed(vma, (unsigned long)vaddr,
+				pfn_to_pfn_t(pfn, PFN_DEV));
 		pfn += usergart[fmt].stride_pfn;
 		vaddr += PAGE_SIZE * m;
 	}
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 8fb7213277cc..bab765a7c501 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -229,7 +229,8 @@ static int ttm_bo_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 		}
 
 		if (vma->vm_flags & VM_MIXEDMAP)
-			ret = vm_insert_mixed(&cvma, address, pfn);
+			ret = vm_insert_mixed(&cvma, address,
+					__pfn_to_pfn_t(pfn, PFN_DEV));
 		else
 			ret = vm_insert_pfn(&cvma, address, pfn);
 
diff --git a/fs/dax.c b/fs/dax.c
index 82897cf3cca0..00088918baf2 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -362,7 +362,7 @@ static int dax_insert_mapping(struct inode *inode, struct buffer_head *bh,
 	}
 	dax_unmap_atomic(bdev, &dax);
 
-	error = vm_insert_mixed(vma, vaddr, pfn_t_to_pfn(dax.pfn));
+	error = vm_insert_mixed(vma, vaddr, dax.pfn);
 
  out:
 	i_mmap_unlock_read(mapping);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c56f63cec895..fb97d2023769 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1056,6 +1056,33 @@ static inline pfn_t page_to_pfn_t(struct page *page)
 	return pfn_to_pfn_t(page_to_pfn(page));
 }
 
+static inline int pfn_t_valid(pfn_t pfn)
+{
+	return pfn_valid(pfn_t_to_pfn(pfn));
+}
+
+#ifdef pfn_pte
+static inline pte_t pfn_t_pte(pfn_t pfn, pgprot_t pgprot)
+{
+	return pfn_pte(pfn_t_to_pfn(pfn), pgprot);
+}
+#endif
+
+#ifdef __HAVE_ARCH_PTE_DEVICE
+static inline bool pfn_t_devmap(pfn_t pfn)
+{
+	const unsigned long flags = PFN_DEV|PFN_MAP;
+
+	return (pfn.val & flags) == flags;
+}
+#else
+static inline bool pfn_t_devmap(pfn_t pfn)
+{
+	return false;
+}
+pte_t pte_mkdevmap(pte_t pte);
+#endif
+
 /*
  * Some inline functions in vmstat.h depend on page_zone()
  */
@@ -1847,6 +1874,10 @@ static inline void pgtable_pmd_page_dtor(struct page *page) {}
 
 #endif
 
+#ifndef pte_devmap
+#define pte_devmap(x) (0)
+#endif
+
 static inline spinlock_t *pmd_lock(struct mm_struct *mm, pmd_t *pmd)
 {
 	spinlock_t *ptl = pmd_lockptr(mm, pmd);
@@ -2266,7 +2297,7 @@ int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn);
 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
-			unsigned long pfn);
+			pfn_t pfn);
 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
 
 
diff --git a/mm/memory.c b/mm/memory.c
index ed00801ce0c7..bba5cfbdf1fe 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1500,7 +1500,7 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 EXPORT_SYMBOL(vm_insert_page);
 
 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
-			unsigned long pfn, pgprot_t prot)
+			pfn_t pfn, pgprot_t prot)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	int retval;
@@ -1516,7 +1516,10 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 		goto out_unlock;
 
 	/* Ok, finally just insert the thing.. */
-	entry = pte_mkspecial(pfn_pte(pfn, prot));
+	if (pfn_t_devmap(pfn))
+		entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
+	else
+		entry = pte_mkspecial(pfn_t_pte(pfn, prot));
 	set_pte_at(mm, addr, pte, entry);
 	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
 
@@ -1566,14 +1569,14 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 	if (track_pfn_insert(vma, &pgprot, pfn))
 		return -EINVAL;
 
-	ret = insert_pfn(vma, addr, pfn, pgprot);
+	ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
 
 	return ret;
 }
 EXPORT_SYMBOL(vm_insert_pfn);
 
 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
-			unsigned long pfn)
+			pfn_t pfn)
 {
 	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
 
@@ -1587,10 +1590,10 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
 	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
 	 * without pte special, it would there be refcounted as a normal page.
 	 */
-	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
+	if (!HAVE_PTE_SPECIAL && pfn_t_valid(pfn)) {
 		struct page *page;
 
-		page = pfn_to_page(pfn);
+		page = pfn_t_to_page(pfn);
 		return insert_page(vma, addr, page, vma->vm_page_prot);
 	}
 	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);

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[PATCH -mm 18/25] mm, dax: convert vmf_insert_pfn_pmd() to pfn_t

[Dan Williams]

Similar to the conversion of vm_insert_mixed() use pfn_t in the
vmf_insert_pfn_pmd() to tag the resulting pte with _PAGE_DEVICE when the
pfn is backed by a devm_memremap_pages() mapping.

Cc: Dave Hansen <dave@sr71.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/sparc/include/asm/pgtable_64.h     |    1 +
 arch/x86/include/asm/pgtable.h          |    6 ++++++
 arch/x86/mm/pat.c                       |    4 ++--
 drivers/gpu/drm/exynos/exynos_drm_gem.c |    2 +-
 drivers/gpu/drm/msm/msm_gem.c           |    2 +-
 drivers/gpu/drm/omapdrm/omap_gem.c      |    4 ++--
 fs/dax.c                                |    2 +-
 include/asm-generic/pgtable.h           |    6 ++++--
 include/linux/huge_mm.h                 |    2 +-
 include/linux/mm.h                      |   10 +++++++++-
 mm/huge_memory.c                        |   10 ++++++----
 mm/memory.c                             |    2 +-
 12 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index e1a49f02b5b4..fdfd8c3a0887 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -245,6 +245,7 @@ static inline pte_t pfn_pte(unsigned long pfn, pgprot_t prot)
 #define mk_pte(page, pgprot)	pfn_pte(page_to_pfn(page), (pgprot))
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pfn_pmd pfn_pmd
 static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
 {
 	pte_t pte = pfn_pte(page_nr, pgprot);
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index d06baa865a50..5209ca1161d2 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -281,6 +281,11 @@ static inline pmd_t pmd_mkdirty(pmd_t pmd)
 	return pmd_set_flags(pmd, _PAGE_DIRTY | _PAGE_SOFT_DIRTY);
 }
 
+static inline pmd_t pmd_mkdevmap(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_DEVMAP);
+}
+
 static inline pmd_t pmd_mkhuge(pmd_t pmd)
 {
 	return pmd_set_flags(pmd, _PAGE_PSE);
@@ -355,6 +360,7 @@ static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
 		     massage_pgprot(pgprot));
 }
 
+#define pfn_pmd pfn_pmd
 static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
 {
 	return __pmd(((phys_addr_t)page_nr << PAGE_SHIFT) |
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 188e3e07eeeb..98efd3c02374 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -949,7 +949,7 @@ int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
 }
 
 int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
-		     unsigned long pfn)
+		     pfn_t pfn)
 {
 	enum page_cache_mode pcm;
 
@@ -957,7 +957,7 @@ int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
 		return 0;
 
 	/* Set prot based on lookup */
-	pcm = lookup_memtype((resource_size_t)pfn << PAGE_SHIFT);
+	pcm = lookup_memtype(pfn_t_to_phys(pfn));
 	*prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) |
 			 cachemode2protval(pcm));
 
diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 973df42fc1eb..d6a6dd7d0ffe 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -491,7 +491,7 @@ int exynos_drm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 
 	pfn = page_to_pfn(exynos_gem->pages[page_offset]);
 	ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address,
-			pfn_to_pfn_t(pfn, PFN_DEV));
+			__pfn_to_pfn_t(pfn, PFN_DEV));
 
 out:
 	switch (ret) {
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 0f4ed5bfda83..6509d9b23912 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -223,7 +223,7 @@ int msm_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 			pfn, pfn << PAGE_SHIFT);
 
 	ret = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address,
-			pfn_to_pfn_t(pfn, PFN_DEV));
+			__pfn_to_pfn_t(pfn, PFN_DEV));
 
 out_unlock:
 	mutex_unlock(&dev->struct_mutex);
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index 910cb276a7ea..94b6d23ec202 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -386,7 +386,7 @@ static int fault_1d(struct drm_gem_object *obj,
 			pfn, pfn << PAGE_SHIFT);
 
 	return vm_insert_mixed(vma, (unsigned long)vmf->virtual_address,
-			pfn_to_pfn_t(pfn, PFN_DEV));
+			__pfn_to_pfn_t(pfn, PFN_DEV));
 }
 
 /* Special handling for the case of faulting in 2d tiled buffers */
@@ -480,7 +480,7 @@ static int fault_2d(struct drm_gem_object *obj,
 
 	for (i = n; i > 0; i--) {
 		vm_insert_mixed(vma, (unsigned long)vaddr,
-				pfn_to_pfn_t(pfn, PFN_DEV));
+				__pfn_to_pfn_t(pfn, PFN_DEV));
 		pfn += usergart[fmt].stride_pfn;
 		vaddr += PAGE_SIZE * m;
 	}
diff --git a/fs/dax.c b/fs/dax.c
index 00088918baf2..b9ab7138f5cb 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -692,7 +692,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		dax_unmap_atomic(bdev, &dax);
 
 		result |= vmf_insert_pfn_pmd(vma, address, pmd,
-				pfn_t_to_pfn(dax.pfn), write);
+				dax.pfn, write);
 	}
 
  out:
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 63abda1ac06d..bdff35e90889 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1,6 +1,8 @@
 #ifndef _ASM_GENERIC_PGTABLE_H
 #define _ASM_GENERIC_PGTABLE_H
 
+#include <linux/pfn.h>
+
 #ifndef __ASSEMBLY__
 #ifdef CONFIG_MMU
 
@@ -549,7 +551,7 @@ static inline int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
  * by vm_insert_pfn().
  */
 static inline int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
-				   unsigned long pfn)
+				   pfn_t pfn)
 {
 	return 0;
 }
@@ -577,7 +579,7 @@ extern int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
 			   unsigned long pfn, unsigned long addr,
 			   unsigned long size);
 extern int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
-			    unsigned long pfn);
+			    pfn_t pfn);
 extern int track_pfn_copy(struct vm_area_struct *vma);
 extern void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
 			unsigned long size);
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 72cd942edb22..0af95c1a2666 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -34,7 +34,7 @@ extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 			unsigned long addr, pgprot_t newprot,
 			int prot_numa);
 int vmf_insert_pfn_pmd(struct vm_area_struct *, unsigned long addr, pmd_t *,
-			unsigned long pfn, bool write);
+			pfn_t pfn, bool write);
 
 enum transparent_hugepage_flag {
 	TRANSPARENT_HUGEPAGE_FLAG,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index fb97d2023769..68b11b68b160 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1068,7 +1068,14 @@ static inline pte_t pfn_t_pte(pfn_t pfn, pgprot_t pgprot)
 }
 #endif
 
-#ifdef __HAVE_ARCH_PTE_DEVICE
+#ifdef pfn_pmd
+static inline pmd_t pfn_t_pmd(pfn_t pfn, pgprot_t pgprot)
+{
+	return pfn_pmd(pfn_t_to_pfn(pfn), pgprot);
+}
+#endif
+
+#ifdef __HAVE_ARCH_PTE_DEVMAP
 static inline bool pfn_t_devmap(pfn_t pfn)
 {
 	const unsigned long flags = PFN_DEV|PFN_MAP;
@@ -1081,6 +1088,7 @@ static inline bool pfn_t_devmap(pfn_t pfn)
 	return false;
 }
 pte_t pte_mkdevmap(pte_t pte);
+pmd_t pmd_mkdevmap(pmd_t pmd);
 #endif
 
 /*
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 70323839bd0d..c1491ce1d8ac 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -960,14 +960,16 @@ int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
 }
 
 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
-		pmd_t *pmd, unsigned long pfn, pgprot_t prot, bool write)
+		pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	pmd_t entry;
 	spinlock_t *ptl;
 
 	ptl = pmd_lock(mm, pmd);
-	entry = pmd_mkhuge(pfn_pmd(pfn, prot));
+	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
+	if (pfn_t_devmap(pfn))
+		entry = pmd_mkdevmap(entry);
 	if (write) {
 		entry = pmd_mkyoung(pmd_mkdirty(entry));
 		entry = maybe_pmd_mkwrite(entry, vma);
@@ -978,7 +980,7 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 }
 
 int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
-			pmd_t *pmd, unsigned long pfn, bool write)
+			pmd_t *pmd, pfn_t pfn, bool write)
 {
 	pgprot_t pgprot = vma->vm_page_prot;
 	/*
@@ -990,7 +992,7 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
 						(VM_PFNMAP|VM_MIXEDMAP));
 	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
-	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
+	BUG_ON(!pfn_t_devmap(pfn));
 
 	if (addr < vma->vm_start || addr >= vma->vm_end)
 		return VM_FAULT_SIGBUS;
diff --git a/mm/memory.c b/mm/memory.c
index bba5cfbdf1fe..42a812d3c3af 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1566,7 +1566,7 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 
 	if (addr < vma->vm_start || addr >= vma->vm_end)
 		return -EFAULT;
-	if (track_pfn_insert(vma, &pgprot, pfn))
+	if (track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)))
 		return -EINVAL;
 
 	ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);

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[PATCH -mm 19/25] list: introduce list_del_poison()

[Dan Williams]

ZONE_DEVICE pages always have an elevated count and will never be on an
lru reclaim list.  That space in 'struct page' can be redirected for
other uses, but for safety introduce a poison value that will always
trip __list_add() to assert.  This allows half of the struct list_head
storage to be reclaimed with some assurance to back up the assumption
that the page count never goes to zero and a list_add() is never
attempted.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 include/linux/list.h |   17 +++++++++++++++++
 lib/list_debug.c     |    4 ++++
 2 files changed, 21 insertions(+)

diff --git a/include/linux/list.h b/include/linux/list.h
index 5356f4d661a7..0d07bc1387aa 100644
--- a/include/linux/list.h
+++ b/include/linux/list.h
@@ -108,9 +108,26 @@ static inline void list_del(struct list_head *entry)
 	entry->next = LIST_POISON1;
 	entry->prev = LIST_POISON2;
 }
+
+#define list_del_poison list_del
 #else
 extern void __list_del_entry(struct list_head *entry);
 extern void list_del(struct list_head *entry);
+extern struct list_head list_force_poison;
+
+/**
+ * list_del_poison - poison an entry to always assert on list_add
+ * @entry: the element to delete and poison
+ *
+ * Note: the assertion on list_add() only occurs when CONFIG_DEBUG_LIST=y,
+ * otherwise this is identical to list_del()
+ */
+static inline void list_del_poison(struct list_head *entry)
+{
+	__list_del(entry->prev, entry->next);
+	entry->next = &list_force_poison;
+	entry->prev = &list_force_poison;
+}
 #endif
 
 /**
diff --git a/lib/list_debug.c b/lib/list_debug.c
index 3859bf63561c..d730c064a4df 100644
--- a/lib/list_debug.c
+++ b/lib/list_debug.c
@@ -12,6 +12,8 @@
 #include <linux/kernel.h>
 #include <linux/rculist.h>
 
+struct list_head list_force_poison;
+
 /*
  * Insert a new entry between two known consecutive entries.
  *
@@ -23,6 +25,8 @@ void __list_add(struct list_head *new,
 			      struct list_head *prev,
 			      struct list_head *next)
 {
+	WARN(new->next == &list_force_poison || new->prev == &list_force_poison,
+		"list_add attempted on force-poisoned entry\n");
 	WARN(next->prev != prev,
 		"list_add corruption. next->prev should be "
 		"prev (%p), but was %p. (next=%p).\n",

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[PATCH -mm 20/25] libnvdimm, pmem: move request_queue allocation earlier in probe

[Dan Williams]

Before the dynamically allocated struct pages from devm_memremap_pages()
can be put to use outside the driver, we need a mechanism to track
whether they are still in use at teardown.  Towards that goal reorder
the initialization sequence to allow the 'q_usage_counter' from the
request_queue to be used by the devm_memremap_pages() implementation (in
subsequent patches).

Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/pmem.c |   33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 1d884318c67b..9060a64628ae 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -124,6 +124,7 @@ static struct pmem_device *pmem_alloc(struct device *dev,
 		struct resource *res, int id)
 {
 	struct pmem_device *pmem;
+	struct request_queue *q;
 
 	pmem = devm_kzalloc(dev, sizeof(*pmem), GFP_KERNEL);
 	if (!pmem)
@@ -141,6 +142,10 @@ static struct pmem_device *pmem_alloc(struct device *dev,
 		return ERR_PTR(-EBUSY);
 	}
 
+	q = blk_alloc_queue_node(GFP_KERNEL, dev_to_node(dev));
+	if (!q)
+		return ERR_PTR(-ENOMEM);
+
 	pmem->pfn_flags = PFN_DEV;
 	if (pmem_should_map_pages(dev)) {
 		pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, res,
@@ -151,9 +156,12 @@ static struct pmem_device *pmem_alloc(struct device *dev,
 				pmem->phys_addr, pmem->size,
 				ARCH_MEMREMAP_PMEM);
 
-	if (IS_ERR(pmem->virt_addr))
+	if (IS_ERR(pmem->virt_addr)) {
+		blk_cleanup_queue(q);
 		return (void __force *) pmem->virt_addr;
+	}
 
+	pmem->pmem_queue = q;
 	return pmem;
 }
 
@@ -173,10 +181,6 @@ static int pmem_attach_disk(struct device *dev,
 	int nid = dev_to_node(dev);
 	struct gendisk *disk;
 
-	pmem->pmem_queue = blk_alloc_queue_node(GFP_KERNEL, nid);
-	if (!pmem->pmem_queue)
-		return -ENOMEM;
-
 	blk_queue_make_request(pmem->pmem_queue, pmem_make_request);
 	blk_queue_physical_block_size(pmem->pmem_queue, PAGE_SIZE);
 	blk_queue_max_hw_sectors(pmem->pmem_queue, UINT_MAX);
@@ -411,19 +415,22 @@ static int nd_pmem_probe(struct device *dev)
 	dev_set_drvdata(dev, pmem);
 	ndns->rw_bytes = pmem_rw_bytes;
 
-	if (is_nd_btt(dev))
+	if (is_nd_btt(dev)) {
+		/* btt allocates its own request_queue */
+		blk_cleanup_queue(pmem->pmem_queue);
+		pmem->pmem_queue = NULL;
 		return nvdimm_namespace_attach_btt(ndns);
+	}
 
 	if (is_nd_pfn(dev))
 		return nvdimm_namespace_attach_pfn(ndns);
 
-	if (nd_btt_probe(ndns, pmem) == 0) {
-		/* we'll come back as btt-pmem */
-		return -ENXIO;
-	}
-
-	if (nd_pfn_probe(ndns, pmem) == 0) {
-		/* we'll come back as pfn-pmem */
+	if (nd_btt_probe(ndns, pmem) == 0 || nd_pfn_probe(ndns, pmem) == 0) {
+		/*
+		 * We'll come back as either btt-pmem, or pfn-pmem, so
+		 * drop the queue allocation for now.
+		 */
+		blk_cleanup_queue(pmem->pmem_queue);
 		return -ENXIO;
 	}
 

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[PATCH -mm 21/25] mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup

[Dan Williams]

get_dev_page() enables paths like get_user_pages() to pin a dynamically
mapped pfn-range (devm_memremap_pages()) while the resulting struct page
objects are in use.  Unlike get_page() it may fail if the device is, or
is in the process of being, disabled.  While the initial lookup of the
range may be an expensive list walk, the result is cached to speed up
subsequent lookups which are likely to be in the same mapped range.

devm_memremap_pages() now requires a reference counter to be specified
at init time.  For pmem this means moving request_queue allocation into
pmem_alloc() so the existing queue usage counter can track "device
pages".

Cc: Dave Hansen <dave@sr71.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/pmem.c    |    6 +++--
 include/linux/mm.h       |   49 +++++++++++++++++++++++++++++++++++++++++--
 include/linux/mm_types.h |    5 ++++
 kernel/memremap.c        |   53 +++++++++++++++++++++++++++++++++++++++++++---
 4 files changed, 105 insertions(+), 8 deletions(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 9060a64628ae..11e483a3fbc9 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -149,7 +149,7 @@ static struct pmem_device *pmem_alloc(struct device *dev,
 	pmem->pfn_flags = PFN_DEV;
 	if (pmem_should_map_pages(dev)) {
 		pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, res,
-				NULL);
+				&q->q_usage_counter, NULL);
 		pmem->pfn_flags |= PFN_MAP;
 	} else
 		pmem->virt_addr = (void __pmem *) devm_memremap(dev,
@@ -323,6 +323,7 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
 	struct vmem_altmap *altmap;
 	struct nd_pfn_sb *pfn_sb;
 	struct pmem_device *pmem;
+	struct request_queue *q;
 	phys_addr_t offset;
 	int rc;
 	struct vmem_altmap __altmap = {
@@ -374,9 +375,10 @@ static int nvdimm_namespace_attach_pfn(struct nd_namespace_common *ndns)
 
 	/* establish pfn range for lookup, and switch to direct map */
 	pmem = dev_get_drvdata(dev);
+	q = pmem->pmem_queue;
 	devm_memunmap(dev, (void __force *) pmem->virt_addr);
 	pmem->virt_addr = (void __pmem *) devm_memremap_pages(dev, &nsio->res,
-			altmap);
+			&q->q_usage_counter, altmap);
 	pmem->pfn_flags |= PFN_MAP;
 	if (IS_ERR(pmem->virt_addr)) {
 		rc = PTR_ERR(pmem->virt_addr);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 68b11b68b160..4166977f51eb 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -15,12 +15,14 @@
 #include <linux/debug_locks.h>
 #include <linux/mm_types.h>
 #include <linux/range.h>
+#include <linux/percpu-refcount.h>
 #include <linux/pfn.h>
 #include <linux/bit_spinlock.h>
 #include <linux/shrinker.h>
 #include <linux/resource.h>
 #include <linux/page_ext.h>
 #include <linux/err.h>
+#include <linux/ioport.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -741,21 +743,25 @@ static inline void vmem_altmap_free(struct vmem_altmap *altmap,
 /**
  * struct dev_pagemap - metadata for ZONE_DEVICE mappings
  * @altmap: pre-allocated/reserved memory for vmemmap allocations
+ * @res: physical address range covered by @ref
+ * @ref: reference count that pins the devm_memremap_pages() mapping
  * @dev: host device of the mapping for debug
  */
 struct dev_pagemap {
 	struct vmem_altmap *altmap;
 	const struct resource *res;
+	struct percpu_ref *ref;
 	struct device *dev;
 };
 
 #ifdef CONFIG_ZONE_DEVICE
 void *devm_memremap_pages(struct device *dev, struct resource *res,
-		struct vmem_altmap *altmap);
+		struct percpu_ref *ref, struct vmem_altmap *altmap);
 struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
 #else
 static inline void *devm_memremap_pages(struct device *dev,
-		struct resource *res, struct vmem_altmap *altmap)
+		struct resource *res, struct percpu_ref *ref,
+		struct vmem_altmap *altmap)
 {
 	/*
 	 * Fail attempts to call devm_memremap_pages() without
@@ -781,6 +787,45 @@ static inline struct vmem_altmap *to_vmem_altmap(unsigned long memmap_start)
 }
 #endif
 
+/**
+ * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
+ * @pfn: page frame number to lookup page_map
+ * @pgmap: optional known pgmap that already has a reference
+ *
+ * @pgmap allows the overhead of a lookup to be bypassed when @pfn lands in the
+ * same mapping.
+ */
+static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
+		struct dev_pagemap *pgmap)
+{
+	const struct resource *res = pgmap ? pgmap->res : NULL;
+	resource_size_t phys = __pfn_to_phys(pfn);
+
+	/*
+	 * In the cached case we're already holding a live reference so
+	 * we can simply do a blind increment
+	 */
+	if (res && phys >= res->start && phys <= res->end) {
+		percpu_ref_get(pgmap->ref);
+		return pgmap;
+	}
+
+	/* fall back to slow path lookup */
+	rcu_read_lock();
+	pgmap = find_dev_pagemap(phys);
+	if (pgmap && !percpu_ref_tryget_live(pgmap->ref))
+		pgmap = NULL;
+	rcu_read_unlock();
+
+	return pgmap;
+}
+
+static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
+{
+	if (pgmap)
+		percpu_ref_put(pgmap->ref);
+}
+
 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
 #define SECTION_IN_PAGE_FLAGS
 #endif
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 22beb225e88f..c67ea476991e 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -116,6 +116,11 @@ struct page {
 					 * Can be used as a generic list
 					 * by the page owner.
 					 */
+		struct dev_pagemap *pgmap; /* ZONE_DEVICE pages are never on an
+					    * lru or handled by a slab
+					    * allocator, this points to the
+					    * hosting device page map.
+					    */
 		struct {		/* slub per cpu partial pages */
 			struct page *next;	/* Next partial slab */
 #ifdef CONFIG_64BIT
diff --git a/kernel/memremap.c b/kernel/memremap.c
index 1fb887227bcb..312e43cd3fa3 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -171,6 +171,29 @@ static void pgmap_radix_release(struct resource *res)
 	mutex_unlock(&pgmap_lock);
 }
 
+static unsigned long pfn_first(struct page_map *page_map)
+{
+	struct dev_pagemap *pgmap = &page_map->pgmap;
+	const struct resource *res = &page_map->res;
+	struct vmem_altmap *altmap = pgmap->altmap;
+	unsigned long pfn;
+
+	pfn = res->start >> PAGE_SHIFT;
+	if (altmap)
+		pfn += vmem_altmap_offset(altmap);
+	return pfn;
+}
+
+static unsigned long pfn_end(struct page_map *page_map)
+{
+	const struct resource *res = &page_map->res;
+
+	return (res->start + resource_size(res)) >> PAGE_SHIFT;
+}
+
+#define for_each_device_pfn(pfn, map) \
+	for (pfn = pfn_first(map); pfn < pfn_end(map); pfn++)
+
 static void devm_memremap_pages_release(struct device *dev, void *data)
 {
 	struct page_map *page_map = data;
@@ -178,6 +201,11 @@ static void devm_memremap_pages_release(struct device *dev, void *data)
 	resource_size_t align_start, align_size;
 	struct dev_pagemap *pgmap = &page_map->pgmap;
 
+	if (percpu_ref_tryget_live(pgmap->ref)) {
+		dev_WARN(dev, "%s: page mapping is still live!\n", __func__);
+		percpu_ref_put(pgmap->ref);
+	}
+
 	pgmap_radix_release(res);
 
 	/* pages are dead and unused, undo the arch mapping */
@@ -203,20 +231,26 @@ struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
  * devm_memremap_pages - remap and provide memmap backing for the given resource
  * @dev: hosting device for @res
  * @res: "host memory" address range
+ * @ref: a live per-cpu reference count
  * @altmap: optional descriptor for allocating the memmap from @res
  *
- * Note, the expectation is that @res is a host memory range that could
- * feasibly be treated as a "System RAM" range, i.e. not a device mmio
- * range, but this is not enforced.
+ * Notes:
+ * 1/ @ref must be 'live' on entry and 'dead' before devm_memunmap_pages() time
+ *    (or devm release event).
+ *
+ * 2/ @res is expected to be a host memory range that could feasibly be
+ *    treated as a "System RAM" range, i.e. not a device mmio range, but
+ *    this is not enforced.
  */
 void *devm_memremap_pages(struct device *dev, struct resource *res,
-		struct vmem_altmap *altmap)
+		struct percpu_ref *ref, struct vmem_altmap *altmap)
 {
 	int is_ram = region_intersects(res->start, resource_size(res),
 			"System RAM");
 	resource_size_t key, align_start, align_size;
 	struct dev_pagemap *pgmap;
 	struct page_map *page_map;
+	unsigned long pfn;
 	int error, nid;
 
 	if (is_ram == REGION_MIXED) {
@@ -234,6 +268,9 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 		return ERR_PTR(-ENXIO);
 	}
 
+	if (!ref)
+		return ERR_PTR(-EINVAL);
+
 	page_map = devres_alloc_node(devm_memremap_pages_release,
 			sizeof(*page_map), GFP_KERNEL, dev_to_node(dev));
 	if (!page_map)
@@ -247,6 +284,7 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 		memcpy(&page_map->altmap, altmap, sizeof(*altmap));
 		pgmap->altmap = &page_map->altmap;
 	}
+	pgmap->ref = ref;
 	pgmap->res = &page_map->res;
 
 	mutex_lock(&pgmap_lock);
@@ -284,6 +322,13 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 	if (error)
 		goto err_add_memory;
 
+	for_each_device_pfn(pfn, page_map) {
+		struct page *page = pfn_to_page(pfn);
+
+		/* ZONE_DEVICE pages never appear on a slab lru */
+		list_del_poison(&page->lru);
+		page->pgmap = pgmap;
+	}
 	devres_add(dev, page_map);
 	return __va(res->start);
 

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[PATCH -mm 22/25] mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd

[Dan Williams]

A dax-huge-page mapping while it uses some thp helpers is ultimately not a
transparent huge page.  The distinction is especially important in the
get_user_pages() path.  pmd_devmap() is used to distinguish dax-pmds from
pmd_huge() and pmd_trans_huge() which have slightly different semantics.

Explicitly mark the pmd_trans_huge() helpers that dax needs by adding
pmd_devmap() checks.

Also, before we introduce usages of pmd_pfn() in common code, include a
definition for archs that have not needed it to date.

Cc: Dave Hansen <dave@sr71.net>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/ia64/include/asm/pgtable.h      |    1 +
 arch/sh/include/asm/pgtable-3level.h |    1 +
 arch/x86/include/asm/pgtable.h       |    8 +++++++-
 include/asm-generic/pgtable.h        |    4 ++++
 include/linux/huge_mm.h              |    3 ++-
 include/linux/mm.h                   |    4 ++++
 mm/huge_memory.c                     |   33 +++++++++++++++++++--------------
 mm/memory.c                          |    8 ++++----
 mm/mprotect.c                        |    5 +++--
 mm/pgtable-generic.c                 |    2 +-
 10 files changed, 46 insertions(+), 23 deletions(-)

diff --git a/arch/ia64/include/asm/pgtable.h b/arch/ia64/include/asm/pgtable.h
index 9f3ed9ee8f13..81d2af23958f 100644
--- a/arch/ia64/include/asm/pgtable.h
+++ b/arch/ia64/include/asm/pgtable.h
@@ -273,6 +273,7 @@ extern unsigned long VMALLOC_END;
 #define pmd_clear(pmdp)			(pmd_val(*(pmdp)) = 0UL)
 #define pmd_page_vaddr(pmd)		((unsigned long) __va(pmd_val(pmd) & _PFN_MASK))
 #define pmd_page(pmd)			virt_to_page((pmd_val(pmd) + PAGE_OFFSET))
+#define pmd_pfn(pmd)			(pmd_val(pmd) >> PAGE_SHIFT)
 
 #define pud_none(pud)			(!pud_val(pud))
 #define pud_bad(pud)			(!ia64_phys_addr_valid(pud_val(pud)))
diff --git a/arch/sh/include/asm/pgtable-3level.h b/arch/sh/include/asm/pgtable-3level.h
index 249a985d9648..bb29a80fb40e 100644
--- a/arch/sh/include/asm/pgtable-3level.h
+++ b/arch/sh/include/asm/pgtable-3level.h
@@ -29,6 +29,7 @@
 
 typedef struct { unsigned long long pmd; } pmd_t;
 #define pmd_val(x)	((x).pmd)
+#define pmd_pfn(x)	((pmd_val(x) & PMD_MASK) >> PAGE_SHIFT)
 #define __pmd(x)	((pmd_t) { (x) } )
 
 static inline unsigned long pud_page_vaddr(pud_t pud)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 5209ca1161d2..d377f950fb9f 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -164,7 +164,13 @@ static inline int pmd_large(pmd_t pte)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static inline int pmd_trans_huge(pmd_t pmd)
 {
-	return pmd_val(pmd) & _PAGE_PSE;
+	return (pmd_val(pmd) & (_PAGE_PSE|_PAGE_DEVMAP)) == _PAGE_PSE;
+}
+
+#define pmd_devmap pmd_devmap
+static inline int pmd_devmap(pmd_t pmd)
+{
+	return !!(pmd_val(pmd) & _PAGE_DEVMAP);
 }
 
 static inline int has_transparent_hugepage(void)
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index bdff35e90889..5459a66a8529 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -616,6 +616,10 @@ static inline int pmd_trans_huge(pmd_t pmd)
 {
 	return 0;
 }
+static inline int pmd_devmap(pmd_t pmd)
+{
+	return 0;
+}
 #ifndef __HAVE_ARCH_PMD_WRITE
 static inline int pmd_write(pmd_t pmd)
 {
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 0af95c1a2666..7deeaa7cc960 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -101,7 +101,8 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 #define split_huge_pmd(__vma, __pmd, __address)				\
 	do {								\
 		pmd_t *____pmd = (__pmd);				\
-		if (pmd_trans_huge(*____pmd))				\
+		if (pmd_trans_huge(*____pmd)				\
+					|| pmd_devmap(*____pmd))	\
 			__split_huge_pmd(__vma, __pmd, __address);	\
 	}  while (0)
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 4166977f51eb..5cad85044e50 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1931,6 +1931,10 @@ static inline void pgtable_pmd_page_dtor(struct page *page) {}
 #define pte_devmap(x) (0)
 #endif
 
+#ifndef pmd_devmap
+#define pmd_devmap(x) (0)
+#endif
+
 static inline spinlock_t *pmd_lock(struct mm_struct *mm, pmd_t *pmd)
 {
 	spinlock_t *ptl = pmd_lockptr(mm, pmd);
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c1491ce1d8ac..1864de3addd1 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1023,7 +1023,7 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 
 	ret = -EAGAIN;
 	pmd = *src_pmd;
-	if (unlikely(!pmd_trans_huge(pmd))) {
+	if (unlikely(!pmd_trans_huge(pmd) && !pmd_devmap(pmd))) {
 		pte_free(dst_mm, pgtable);
 		goto out_unlock;
 	}
@@ -1046,17 +1046,20 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		goto out_unlock;
 	}
 
-	src_page = pmd_page(pmd);
-	VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
-	get_page(src_page);
-	page_dup_rmap(src_page, true);
-	add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+	if (pmd_trans_huge(pmd)) {
+		/* thp accounting separate from pmd_devmap accounting */
+		src_page = pmd_page(pmd);
+		VM_BUG_ON_PAGE(!PageHead(src_page), src_page);
+		get_page(src_page);
+		page_dup_rmap(src_page, true);
+		add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+		atomic_long_inc(&dst_mm->nr_ptes);
+		pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
+	}
 
 	pmdp_set_wrprotect(src_mm, addr, src_pmd);
 	pmd = pmd_mkold(pmd_wrprotect(pmd));
-	pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable);
 	set_pmd_at(dst_mm, addr, dst_pmd, pmd);
-	atomic_long_inc(&dst_mm->nr_ptes);
 
 	ret = 0;
 out_unlock:
@@ -1673,7 +1676,7 @@ bool __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
 		spinlock_t **ptl)
 {
 	*ptl = pmd_lock(vma->vm_mm, pmd);
-	if (likely(pmd_trans_huge(*pmd)))
+	if (likely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd)))
 		return true;
 	spin_unlock(*ptl);
 	return false;
@@ -2790,7 +2793,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
 	VM_BUG_ON(haddr & ~HPAGE_PMD_MASK);
 	VM_BUG_ON_VMA(vma->vm_start > haddr, vma);
 	VM_BUG_ON_VMA(vma->vm_end < haddr + HPAGE_PMD_SIZE, vma);
-	VM_BUG_ON(!pmd_trans_huge(*pmd));
+	VM_BUG_ON(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd));
 
 	count_vm_event(THP_SPLIT_PMD);
 
@@ -2900,11 +2903,13 @@ void __split_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 
 	mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
 	ptl = pmd_lock(mm, pmd);
-	if (unlikely(!pmd_trans_huge(*pmd)))
+	if (unlikely(!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)))
 		goto out;
-	page = pmd_page(*pmd);
 	__split_huge_pmd_locked(vma, pmd, haddr, false);
-	if (PageMlocked(page))
+
+	if (pmd_trans_huge(*pmd))
+		page = pmd_page(*pmd);
+	if (page && PageMlocked(page))
 		get_page(page);
 	else
 		page = NULL;
@@ -2937,7 +2942,7 @@ static void split_huge_pmd_address(struct vm_area_struct *vma,
 		return;
 
 	pmd = pmd_offset(pud, address);
-	if (!pmd_present(*pmd) || !pmd_trans_huge(*pmd))
+	if (!pmd_present(*pmd) || (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)))
 		return;
 	/*
 	 * Caller holds the mmap_sem write mode, so a huge pmd cannot
diff --git a/mm/memory.c b/mm/memory.c
index 42a812d3c3af..0b8a42e15610 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -949,7 +949,7 @@ static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src
 	src_pmd = pmd_offset(src_pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
-		if (pmd_trans_huge(*src_pmd)) {
+		if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
 			int err;
 			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
 			err = copy_huge_pmd(dst_mm, src_mm,
@@ -1176,7 +1176,7 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
-		if (pmd_trans_huge(*pmd)) {
+		if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
 			if (next - addr != HPAGE_PMD_SIZE) {
 #ifdef CONFIG_DEBUG_VM
 				if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
@@ -3357,7 +3357,7 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 		int ret;
 
 		barrier();
-		if (pmd_trans_huge(orig_pmd)) {
+		if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
 			unsigned int dirty = flags & FAULT_FLAG_WRITE;
 
 			if (pmd_protnone(orig_pmd))
@@ -3386,7 +3386,7 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 	    unlikely(__pte_alloc(mm, vma, pmd, address)))
 		return VM_FAULT_OOM;
 	/* if an huge pmd materialized from under us just retry later */
-	if (unlikely(pmd_trans_huge(*pmd)))
+	if (unlikely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd)))
 		return 0;
 	/*
 	 * A regular pmd is established and it can't morph into a huge pmd
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 9c1445dc8a4c..732e07baf76c 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -149,7 +149,8 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
 		unsigned long this_pages;
 
 		next = pmd_addr_end(addr, end);
-		if (!pmd_trans_huge(*pmd) && pmd_none_or_clear_bad(pmd))
+		if (!pmd_trans_huge(*pmd) && !pmd_devmap(*pmd)
+				&& pmd_none_or_clear_bad(pmd))
 			continue;
 
 		/* invoke the mmu notifier if the pmd is populated */
@@ -158,7 +159,7 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
 			mmu_notifier_invalidate_range_start(mm, mni_start, end);
 		}
 
-		if (pmd_trans_huge(*pmd)) {
+		if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
 			if (next - addr != HPAGE_PMD_SIZE)
 				split_huge_pmd(vma, pmd, addr);
 			else {
diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
index c311a2ec6fea..9d4767698a1c 100644
--- a/mm/pgtable-generic.c
+++ b/mm/pgtable-generic.c
@@ -132,7 +132,7 @@ pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
 {
 	pmd_t pmd;
 	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
-	VM_BUG_ON(!pmd_trans_huge(*pmdp));
+	VM_BUG_ON(!pmd_trans_huge(*pmdp) && !pmd_devmap(*pmdp));
 	pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
 	flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
 	return pmd;

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[PATCH -mm 23/25] mm, x86: get_user_pages() for dax mappings

[Dan Williams]

A dax mapping establishes a pte with _PAGE_DEVMAP set when the driver
has established a devm_memremap_pages() mapping, i.e. when the pfn_t
return from ->direct_access() has PFN_DEV and PFN_MAP set.  Later, when
encountering _PAGE_DEVMAP during a page table walk we lookup and pin a
struct dev_pagemap instance to keep the result of pfn_to_page() valid
until put_page().

Cc: Dave Hansen <dave@sr71.net>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 arch/x86/mm/gup.c       |   56 ++++++++++++++++++++++++++++++++++--
 include/linux/huge_mm.h |   10 ++++++
 include/linux/mm.h      |   35 ++++++++++++++++------
 mm/gup.c                |   18 +++++++++++
 mm/huge_memory.c        |   74 +++++++++++++++++++++++++++++++++++++----------
 mm/swap.c               |   15 ++++++++++
 6 files changed, 178 insertions(+), 30 deletions(-)

diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index f8cb3e8ac250..26602434c33a 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -63,6 +63,16 @@ retry:
 #endif
 }
 
+static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages)
+{
+	while ((*nr) - nr_start) {
+		struct page *page = pages[--(*nr)];
+
+		ClearPageReferenced(page);
+		put_page(page);
+	}
+}
+
 /*
  * The performance critical leaf functions are made noinline otherwise gcc
  * inlines everything into a single function which results in too much
@@ -71,7 +81,9 @@ retry:
 static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
 		unsigned long end, int write, struct page **pages, int *nr)
 {
+	struct dev_pagemap *pgmap = NULL;
 	unsigned long mask;
+	int nr_start = *nr;
 	pte_t *ptep;
 
 	mask = _PAGE_PRESENT|_PAGE_USER;
@@ -89,13 +101,21 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
 			return 0;
 		}
 
-		if ((pte_flags(pte) & (mask | _PAGE_SPECIAL)) != mask) {
+		page = pte_page(pte);
+		if (pte_devmap(pte)) {
+			pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
+			if (unlikely(!pgmap)) {
+				undo_dev_pagemap(nr, nr_start, pages);
+				pte_unmap(ptep);
+				return 0;
+			}
+		} else if ((pte_flags(pte) & (mask | _PAGE_SPECIAL)) != mask) {
 			pte_unmap(ptep);
 			return 0;
 		}
 		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
-		page = pte_page(pte);
 		get_page(page);
+		put_dev_pagemap(pgmap);
 		SetPageReferenced(page);
 		pages[*nr] = page;
 		(*nr)++;
@@ -114,6 +134,32 @@ static inline void get_head_page_multiple(struct page *page, int nr)
 	SetPageReferenced(page);
 }
 
+static int __gup_device_huge_pmd(pmd_t pmd, unsigned long addr,
+		unsigned long end, struct page **pages, int *nr)
+{
+	int nr_start = *nr;
+	unsigned long pfn = pmd_pfn(pmd);
+	struct dev_pagemap *pgmap = NULL;
+
+	pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
+	do {
+		struct page *page = pfn_to_page(pfn);
+
+		pgmap = get_dev_pagemap(pfn, pgmap);
+		if (unlikely(!pgmap)) {
+			undo_dev_pagemap(nr, nr_start, pages);
+			return 0;
+		}
+		SetPageReferenced(page);
+		pages[*nr] = page;
+		get_page(page);
+		put_dev_pagemap(pgmap);
+		(*nr)++;
+		pfn++;
+	} while (addr += PAGE_SIZE, addr != end);
+	return 1;
+}
+
 static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
 		unsigned long end, int write, struct page **pages, int *nr)
 {
@@ -126,9 +172,13 @@ static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
 		mask |= _PAGE_RW;
 	if ((pmd_flags(pmd) & mask) != mask)
 		return 0;
+
+	VM_BUG_ON(!pfn_valid(pmd_pfn(pmd)));
+	if (pmd_devmap(pmd))
+		return __gup_device_huge_pmd(pmd, addr, end, pages, nr);
+
 	/* hugepages are never "special" */
 	VM_BUG_ON(pmd_flags(pmd) & _PAGE_SPECIAL);
-	VM_BUG_ON(!pfn_valid(pmd_pfn(pmd)));
 
 	refs = 0;
 	head = pmd_page(pmd);
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 7deeaa7cc960..436283fac6c5 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -35,7 +35,6 @@ extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 			int prot_numa);
 int vmf_insert_pfn_pmd(struct vm_area_struct *, unsigned long addr, pmd_t *,
 			pfn_t pfn, bool write);
-
 enum transparent_hugepage_flag {
 	TRANSPARENT_HUGEPAGE_FLAG,
 	TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
@@ -52,6 +51,9 @@ enum transparent_hugepage_flag {
 #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
+struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
+		pmd_t *pmd, int flags);
+
 #define HPAGE_PMD_SHIFT PMD_SHIFT
 #define HPAGE_PMD_SIZE	((1UL) << HPAGE_PMD_SHIFT)
 #define HPAGE_PMD_MASK	(~(HPAGE_PMD_SIZE - 1))
@@ -202,6 +204,12 @@ static inline bool is_huge_zero_page(struct page *page)
 	return false;
 }
 
+
+static inline struct page *follow_devmap_pmd(struct vm_area_struct *vma,
+		unsigned long addr, pmd_t *pmd, int flags)
+{
+	return NULL;
+}
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 #endif /* _LINUX_HUGE_MM_H */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5cad85044e50..713aec7ad81a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -456,16 +456,7 @@ static inline int page_count(struct page *page)
 	return atomic_read(&compound_head(page)->_count);
 }
 
-static inline void get_page(struct page *page)
-{
-	page = compound_head(page);
-	/*
-	 * Getting a normal page or the head of a compound page
-	 * requires to already have an elevated page->_count.
-	 */
-	VM_BUG_ON_PAGE(atomic_read(&page->_count) <= 0, page);
-	atomic_inc(&page->_count);
-}
+extern bool __get_page_tail(struct page *page);
 
 static inline struct page *virt_to_head_page(const void *x)
 {
@@ -758,6 +749,11 @@ struct dev_pagemap {
 void *devm_memremap_pages(struct device *dev, struct resource *res,
 		struct percpu_ref *ref, struct vmem_altmap *altmap);
 struct dev_pagemap *find_dev_pagemap(resource_size_t phys);
+
+static inline bool is_zone_device_page(const struct page *page)
+{
+	return page_zonenum(page) == ZONE_DEVICE;
+}
 #else
 static inline void *devm_memremap_pages(struct device *dev,
 		struct resource *res, struct percpu_ref *ref,
@@ -776,6 +772,11 @@ static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)
 {
 	return NULL;
 }
+
+static inline bool is_zone_device_page(const struct page *page)
+{
+	return false;
+}
 #endif
 
 #if defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_ZONE_DEVICE)
@@ -826,6 +827,20 @@ static inline void put_dev_pagemap(struct dev_pagemap *pgmap)
 		percpu_ref_put(pgmap->ref);
 }
 
+static inline void get_page(struct page *page)
+{
+	if (is_zone_device_page(page))
+		percpu_ref_get(page->pgmap->ref);
+
+	page = compound_head(page);
+	/*
+	 * Getting a normal page or the head of a compound page
+	 * requires to already have an elevated page->_count.
+	 */
+	VM_BUG_ON_PAGE(atomic_read(&page->_count) <= 0, page);
+	atomic_inc(&page->_count);
+}
+
 #if defined(CONFIG_SPARSEMEM) && !defined(CONFIG_SPARSEMEM_VMEMMAP)
 #define SECTION_IN_PAGE_FLAGS
 #endif
diff --git a/mm/gup.c b/mm/gup.c
index e95b0cb6ed81..60b86f2fbe95 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -98,7 +98,16 @@ retry:
 	}
 
 	page = vm_normal_page(vma, address, pte);
-	if (unlikely(!page)) {
+	if (!page && pte_devmap(pte) && (flags & FOLL_GET)) {
+		/*
+		 * Only return device mapping pages in the FOLL_GET case since
+		 * they are only valid while holding the pgmap reference.
+		 */
+		if (get_dev_pagemap(pte_pfn(pte), NULL))
+			page = pte_page(pte);
+		else
+			goto no_page;
+	} else if (unlikely(!page)) {
 		if (flags & FOLL_DUMP) {
 			/* Avoid special (like zero) pages in core dumps */
 			page = ERR_PTR(-EFAULT);
@@ -237,6 +246,13 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
 	}
 	if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
 		return no_page_table(vma, flags);
+	if (pmd_devmap(*pmd)) {
+		ptl = pmd_lock(mm, pmd);
+		page = follow_devmap_pmd(vma, address, pmd, flags);
+		spin_unlock(ptl);
+		if (page)
+			return page;
+	}
 	if (likely(!pmd_trans_huge(*pmd)))
 		return follow_page_pte(vma, address, pmd, flags);
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1864de3addd1..1254a0d8669e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1002,6 +1002,63 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 	return VM_FAULT_NOPAGE;
 }
 
+static void touch_pmd(struct vm_area_struct *vma, unsigned long addr,
+		pmd_t *pmd)
+{
+	pmd_t _pmd;
+
+	/*
+	 * We should set the dirty bit only for FOLL_WRITE but for now
+	 * the dirty bit in the pmd is meaningless.  And if the dirty
+	 * bit will become meaningful and we'll only set it with
+	 * FOLL_WRITE, an atomic set_bit will be required on the pmd to
+	 * set the young bit, instead of the current set_pmd_at.
+	 */
+	_pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
+	if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
+				pmd, _pmd,  1))
+		update_mmu_cache_pmd(vma, addr, pmd);
+}
+
+struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
+		pmd_t *pmd, int flags)
+{
+	unsigned long pfn = pmd_pfn(*pmd);
+	struct mm_struct *mm = vma->vm_mm;
+	struct dev_pagemap *pgmap;
+	struct page *page;
+
+	assert_spin_locked(pmd_lockptr(mm, pmd));
+
+	if (flags & FOLL_WRITE && !pmd_write(*pmd))
+		return NULL;
+
+	if (pmd_present(*pmd) && pmd_devmap(*pmd))
+		/* pass */;
+	else
+		return NULL;
+
+	if (flags & FOLL_TOUCH)
+		touch_pmd(vma, addr, pmd);
+
+	/*
+	 * device mapped pages can only be returned if the
+	 * caller will manage the page reference count.
+	 */
+	if (!(flags & FOLL_GET))
+		return ERR_PTR(-EEXIST);
+
+	pfn += (addr & ~PMD_MASK) >> PAGE_SHIFT;
+	pgmap = get_dev_pagemap(pfn, NULL);
+	if (!pgmap)
+		return ERR_PTR(-EFAULT);
+	page = pfn_to_page(pfn);
+	get_page(page);
+	put_dev_pagemap(pgmap);
+
+	return page;
+}
+
 int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		  pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
 		  struct vm_area_struct *vma)
@@ -1359,21 +1416,8 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 
 	page = pmd_page(*pmd);
 	VM_BUG_ON_PAGE(!PageHead(page), page);
-	if (flags & FOLL_TOUCH) {
-		pmd_t _pmd;
-		/*
-		 * We should set the dirty bit only for FOLL_WRITE but
-		 * for now the dirty bit in the pmd is meaningless.
-		 * And if the dirty bit will become meaningful and
-		 * we'll only set it with FOLL_WRITE, an atomic
-		 * set_bit will be required on the pmd to set the
-		 * young bit, instead of the current set_pmd_at.
-		 */
-		_pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
-		if (pmdp_set_access_flags(vma, addr & HPAGE_PMD_MASK,
-					  pmd, _pmd,  1))
-			update_mmu_cache_pmd(vma, addr, pmd);
-	}
+	if (flags & FOLL_TOUCH)
+		touch_pmd(vma, addr, pmd);
 	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
 		/*
 		 * We don't mlock() pte-mapped THPs. This way we can avoid
diff --git a/mm/swap.c b/mm/swap.c
index abffc33bb975..496a39bbfab5 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -89,10 +89,25 @@ static void __put_compound_page(struct page *page)
 	(*dtor)(page);
 }
 
+static bool put_device_page(struct page *page)
+{
+	/*
+	 * ZONE_DEVICE pages are never "onlined" so their reference
+	 * counts never reach zero.  They are always owned by a device
+	 * driver, not the mm core.  I.e. the page is 'idle' when the
+	 * count is 1.
+	 */
+	VM_BUG_ON_PAGE(atomic_read(&page->_count) == 1, page);
+	put_dev_pagemap(page->pgmap);
+	return atomic_dec_return(&page->_count) == 1;
+}
+
 void __put_page(struct page *page)
 {
 	if (unlikely(PageCompound(page)))
 		__put_compound_page(page);
+	else if (is_zone_device_page(page))
+		put_device_page(page);
 	else
 		__put_single_page(page);
 }

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[PATCH -mm 24/25] dax: provide diagnostics for pmd mapping failures

[Dan Williams]

There is a wide gamut of conditions that can trigger the dax pmd path to
fallback to pte mappings.  Ideally we'd have a syscall interface to
determine mapping characteristics after the fact.  In the meantime
provide debug messages.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 fs/dax.c |   57 ++++++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 48 insertions(+), 9 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index b9ab7138f5cb..7bfe6cd59636 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -557,6 +557,14 @@ EXPORT_SYMBOL_GPL(dax_fault);
  */
 #define PG_PMD_COLOUR	((PMD_SIZE >> PAGE_SHIFT) - 1)
 
+static void dax_pmd_dbg(struct block_device *bdev, unsigned long address,
+		const char *reason)
+{
+	pr_debug("%s%s dax_pmd: %s addr: %lx fallback: %s\n", bdev
+			? dev_name(part_to_dev(bdev->bd_part)) : "", bdev
+			? ": " : "", current->comm, address, reason);
+}
+
 int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		pmd_t *pmd, unsigned int flags, get_block_t get_block,
 		dax_iodone_t complete_unwritten)
@@ -568,7 +576,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	unsigned blkbits = inode->i_blkbits;
 	unsigned long pmd_addr = address & PMD_MASK;
 	bool write = flags & FAULT_FLAG_WRITE;
-	struct block_device *bdev;
+	struct block_device *bdev = NULL;
 	pgoff_t size, pgoff;
 	sector_t block;
 	int result = 0;
@@ -580,21 +588,29 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	/* Fall back to PTEs if we're going to COW */
 	if (write && !(vma->vm_flags & VM_SHARED)) {
 		split_huge_pmd(vma, pmd, address);
+		dax_pmd_dbg(bdev, address, "cow write");
 		return VM_FAULT_FALLBACK;
 	}
 	/* If the PMD would extend outside the VMA */
-	if (pmd_addr < vma->vm_start)
+	if (pmd_addr < vma->vm_start) {
+		dax_pmd_dbg(bdev, address, "vma start unaligned");
 		return VM_FAULT_FALLBACK;
-	if ((pmd_addr + PMD_SIZE) > vma->vm_end)
+	}
+	if ((pmd_addr + PMD_SIZE) > vma->vm_end) {
+		dax_pmd_dbg(bdev, address, "vma end unaligned");
 		return VM_FAULT_FALLBACK;
+	}
 
 	pgoff = linear_page_index(vma, pmd_addr);
 	size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	if (pgoff >= size)
 		return VM_FAULT_SIGBUS;
 	/* If the PMD would cover blocks out of the file */
-	if ((pgoff | PG_PMD_COLOUR) >= size)
+	if ((pgoff | PG_PMD_COLOUR) >= size) {
+		dax_pmd_dbg(bdev, address,
+				"offset + huge page size > file size");
 		return VM_FAULT_FALLBACK;
+	}
 
 	memset(&bh, 0, sizeof(bh));
 	block = (sector_t)pgoff << (PAGE_SHIFT - blkbits);
@@ -610,8 +626,10 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	 * just fall back to PTEs.  Calling get_block 512 times in a loop
 	 * would be silly.
 	 */
-	if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE)
+	if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) {
+		dax_pmd_dbg(bdev, address, "block allocation size invalid");
 		goto fallback;
+	}
 
 	/*
 	 * If we allocated new storage, make sure no process has any
@@ -634,23 +652,33 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		result = VM_FAULT_SIGBUS;
 		goto out;
 	}
-	if ((pgoff | PG_PMD_COLOUR) >= size)
+	if ((pgoff | PG_PMD_COLOUR) >= size) {
+		dax_pmd_dbg(bdev, address, "pgoff unaligned");
 		goto fallback;
+	}
 
 	if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) {
 		spinlock_t *ptl;
 		pmd_t entry;
 		struct page *zero_page = get_huge_zero_page();
 
-		if (unlikely(!zero_page))
+		if (unlikely(!zero_page)) {
+			dax_pmd_dbg(bdev, address, "no zero page");
 			goto fallback;
+		}
 
 		ptl = pmd_lock(vma->vm_mm, pmd);
 		if (!pmd_none(*pmd)) {
 			spin_unlock(ptl);
+			dax_pmd_dbg(bdev, address, "pmd already present");
 			goto fallback;
 		}
 
+		dev_dbg(part_to_dev(bdev->bd_part),
+				"%s: %s addr: %lx pfn: <zero> sect: %llx\n",
+				__func__, current->comm, address,
+				(unsigned long long) to_sector(&bh, inode));
+
 		entry = mk_pmd(zero_page, vma->vm_page_prot);
 		entry = pmd_mkhuge(entry);
 		set_pmd_at(vma->vm_mm, pmd_addr, pmd, entry);
@@ -667,8 +695,13 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 			result = VM_FAULT_SIGBUS;
 			goto out;
 		}
-		if (length < PMD_SIZE
-				|| (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR)) {
+		if (length < PMD_SIZE) {
+			dax_pmd_dbg(bdev, address, "dax-length too small");
+			dax_unmap_atomic(bdev, &dax);
+			goto fallback;
+		}
+		if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR) {
+			dax_pmd_dbg(bdev, address, "pfn unaligned");
 			dax_unmap_atomic(bdev, &dax);
 			goto fallback;
 		}
@@ -679,6 +712,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		 */
 		if (pfn_t_has_page(dax.pfn)) {
 			dax_unmap_atomic(bdev, &dax);
+			dax_pmd_dbg(bdev, address, "pfn not in memmap");
 			goto fallback;
 		}
 
@@ -691,6 +725,11 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 		}
 		dax_unmap_atomic(bdev, &dax);
 
+		dev_dbg(part_to_dev(bdev->bd_part),
+				"%s: %s addr: %lx pfn: %lx sect: %llx\n",
+				__func__, current->comm, address,
+				pfn_t_to_pfn(dax.pfn),
+				(unsigned long long) dax.sector);
 		result |= vmf_insert_pfn_pmd(vma, address, pmd,
 				dax.pfn, write);
 	}

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[PATCH -mm 25/25] dax: re-enable dax pmd mappings

[Dan Williams]

Now that the get_user_pages() path knows how to handle dax-pmd mappings,
remove the protections that disabled dax-pmd support.

Tests available from github.com/pmem/ndctl:

    make TESTS="lib/test-dax.sh lib/test-mmap.sh" check

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 fs/Kconfig |    3 ++-
 fs/dax.c   |    8 ++------
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/fs/Kconfig b/fs/Kconfig
index 7a6ff07c183f..922893f8ab4a 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -50,7 +50,8 @@ config FS_DAX_PMD
 	bool
 	default FS_DAX
 	depends on FS_DAX
-	depends on BROKEN
+	depends on ZONE_DEVICE
+	depends on TRANSPARENT_HUGEPAGE
 
 endif # BLOCK
 
diff --git a/fs/dax.c b/fs/dax.c
index 7bfe6cd59636..27ad9ac54de5 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -581,7 +581,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 	sector_t block;
 	int result = 0;
 
-	/* dax pmd mappings are broken wrt gup and fork */
+	/* dax pmd mappings require pfn_t_devmap() */
 	if (!IS_ENABLED(CONFIG_FS_DAX_PMD))
 		return VM_FAULT_FALLBACK;
 
@@ -706,11 +706,7 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address,
 			goto fallback;
 		}
 
-		/*
-		 * TODO: teach vmf_insert_pfn_pmd() to support
-		 * 'pte_special' for pmds
-		 */
-		if (pfn_t_has_page(dax.pfn)) {
+		if (!pfn_t_devmap(dax.pfn)) {
 			dax_unmap_atomic(bdev, &dax);
 			dax_pmd_dbg(bdev, address, "pfn not in memmap");
 			goto fallback;

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Re: [PATCH -mm 00/25] get_user_pages() for dax pte and pmd mappings

[Logan Gunthorpe]

Hi Dan,

Perfect. This latest version of the patch set is once again passing all
my tests without any issues.

Tested-By: Logan Gunthorpe <logang@deltatee.com>

Thanks,

Logan


On 07/12/15 06:32 PM, Dan Williams wrote:
> Andrew, please pull dax-gup support into -mm.
> 
> This series, based on next-20151203, has been out for review in one form
> or another since September [1].  The concept was reviewed at Kernel
> Summit in the "ZONE_DEVICE" tech-topic presentation.  Since the RFC
> posting [2] it has received fixes and is now passing the unit tests from
> ndctl [3] and nvml [4].
> 
> Logan Gunthorpe has also offered up functional testing of his use case
> for devm_memremap_pages() [5] (a "Tested-by" for the latest revision is
> still pending).
> 
> [1]: https://lists.01.org/pipermail/linux-nvdimm/2015-September/002199.html
> [2]: https://lists.01.org/pipermail/linux-nvdimm/2015-November/003033.html
> [3]: https://github.com/pmem/ndctl
> [4]: https://github.com/pmem/nvml
> [5]: https://lists.01.org/pipermail/linux-nvdimm/2015-October/002576.html
> 
> A git tree of this set is available here:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/djbw/nvdimm libnvdimm-pending
> 
> The libnvdimm-pending branch has received a build success notification
> from the kbuild-test-robot over 105 configs.
> 
> ---
> 
> Summary:
> 
> To date, we have implemented two I/O usage models for persistent memory,
> PMEM (a persistent "ram disk") and DAX (mmap persistent memory into
> userspace).  This series adds a third, DAX-GUP, that allows DAX mappings
> to be the target of direct-i/o.  It allows userspace to coordinate
> DMA/RDMA from/to persistent memory.
> 
> The implementation leverages the ZONE_DEVICE mm-zone that went into
> 4.3-rc1 (also discussed at kernel summit) to flag pages that are owned
> and dynamically mapped by a device driver.  The pmem driver, after
> mapping a persistent memory range into the system memmap via
> devm_memremap_pages(), arranges for DAX to distinguish pfn-only versus
> page-backed pmem-pfns via flags in the new pfn_t type.
> 
> The DAX code, upon seeing a PFN_DEV+PFN_MAP flagged pfn, flags the
> resulting pte(s) inserted into the process page tables with a new
> _PAGE_DEVMAP flag.  Later, when get_user_pages() is walking ptes it keys
> off _PAGE_DEVMAP to pin the device hosting the page range active.
> Finally, get_page() and put_page() are modified to take references
> against the device driver established page mapping.
> 
> Finally, this need for "struct page" for persistent memory requires
> memory capacity to store the memmap array.  Given the memmap array for a
> large pool of persistent may exhaust available DRAM introduce a
> mechanism to allocate the memmap from persistent memory.  The new "struct
> vmem_altmap *"  parameter to devm_memremap_pages() enables
> arch_add_memory() to use reserved pmem capacity rather than the page
> allocator.
> 
> ---
> 
> Dan Williams (23):
>       pmem, dax: clean up clear_pmem()
>       dax: increase granularity of dax_clear_blocks() operations
>       dax: guarantee page aligned results from bdev_direct_access()
>       dax: fix lifetime of in-kernel dax mappings with dax_map_atomic()
>       um: kill pfn_t
>       kvm: rename pfn_t to kvm_pfn_t
>       mm, dax, pmem: introduce pfn_t
>       mm: introduce find_dev_pagemap()
>       x86, mm: introduce vmem_altmap to augment vmemmap_populate()
>       libnvdimm, pfn, pmem: allocate memmap array in persistent memory
>       avr32: convert to asm-generic/memory_model.h
>       hugetlb: fix compile error on tile
>       frv: fix compiler warning from definition of __pmd()
>       x86, mm: introduce _PAGE_DEVMAP
>       mm, dax, gpu: convert vm_insert_mixed to pfn_t
>       mm, dax: convert vmf_insert_pfn_pmd() to pfn_t
>       list: introduce list_del_poison()
>       libnvdimm, pmem: move request_queue allocation earlier in probe
>       mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup
>       mm, dax: dax-pmd vs thp-pmd vs hugetlbfs-pmd
>       mm, x86: get_user_pages() for dax mappings
>       dax: provide diagnostics for pmd mapping failures
>       dax: re-enable dax pmd mappings
> 
> Ross Zwisler (1):
>       mm, dax: fix livelock, allow dax pmd mappings to become writeable
> 
> Toshi Kani (1):
>       dax: Split pmd map when fallback on COW
> 
> 
>  arch/alpha/include/asm/pgtable.h        |    1 
>  arch/arm/include/asm/kvm_mmu.h          |    5 -
>  arch/arm/kvm/mmu.c                      |   10 +
>  arch/arm64/include/asm/kvm_mmu.h        |    3 
>  arch/avr32/include/asm/page.h           |    8 -
>  arch/frv/include/asm/page.h             |    2 
>  arch/ia64/include/asm/page.h            |    1 
>  arch/ia64/include/asm/pgtable.h         |    1 
>  arch/m68k/include/asm/page_mm.h         |    1 
>  arch/m68k/include/asm/page_no.h         |    1 
>  arch/mips/include/asm/kvm_host.h        |    6 -
>  arch/mips/kvm/emulate.c                 |    2 
>  arch/mips/kvm/tlb.c                     |   14 +
>  arch/mn10300/include/asm/page.h         |    1 
>  arch/parisc/include/asm/pgtable.h       |    1 
>  arch/powerpc/include/asm/kvm_book3s.h   |    4 
>  arch/powerpc/include/asm/kvm_ppc.h      |    2 
>  arch/powerpc/include/asm/pgtable.h      |    1 
>  arch/powerpc/kvm/book3s.c               |    6 -
>  arch/powerpc/kvm/book3s_32_mmu_host.c   |    2 
>  arch/powerpc/kvm/book3s_64_mmu_host.c   |    2 
>  arch/powerpc/kvm/e500.h                 |    2 
>  arch/powerpc/kvm/e500_mmu_host.c        |    8 -
>  arch/powerpc/kvm/trace_pr.h             |    2 
>  arch/powerpc/sysdev/axonram.c           |    8 -
>  arch/sh/include/asm/pgtable-3level.h    |    1 
>  arch/sparc/include/asm/pgtable_64.h     |    2 
>  arch/tile/include/asm/pgtable.h         |    1 
>  arch/um/include/asm/page.h              |    7 -
>  arch/um/include/asm/pgtable-3level.h    |    5 -
>  arch/um/include/asm/pgtable.h           |    2 
>  arch/x86/include/asm/page_types.h       |    3 
>  arch/x86/include/asm/pgtable.h          |   26 +++
>  arch/x86/include/asm/pgtable_types.h    |    7 +
>  arch/x86/include/asm/pmem.h             |    7 -
>  arch/x86/kvm/iommu.c                    |   11 +
>  arch/x86/kvm/mmu.c                      |   37 ++--
>  arch/x86/kvm/mmu_audit.c                |    2 
>  arch/x86/kvm/paging_tmpl.h              |    6 -
>  arch/x86/kvm/vmx.c                      |    2 
>  arch/x86/kvm/x86.c                      |    2 
>  arch/x86/mm/gup.c                       |   56 +++++-
>  arch/x86/mm/init_64.c                   |   32 +++
>  arch/x86/mm/pat.c                       |    4 
>  drivers/block/brd.c                     |    4 
>  drivers/gpu/drm/exynos/exynos_drm_gem.c |    3 
>  drivers/gpu/drm/gma500/framebuffer.c    |    3 
>  drivers/gpu/drm/msm/msm_gem.c           |    3 
>  drivers/gpu/drm/omapdrm/omap_gem.c      |    6 -
>  drivers/gpu/drm/ttm/ttm_bo_vm.c         |    3 
>  drivers/nvdimm/pfn_devs.c               |    3 
>  drivers/nvdimm/pmem.c                   |   70 +++++--
>  drivers/s390/block/dcssblk.c            |   10 -
>  fs/Kconfig                              |    3 
>  fs/block_dev.c                          |   15 +-
>  fs/dax.c                                |  290 +++++++++++++++++++----------
>  include/asm-generic/pgtable.h           |   10 +
>  include/linux/blkdev.h                  |   19 ++
>  include/linux/huge_mm.h                 |   15 +-
>  include/linux/hugetlb.h                 |    1 
>  include/linux/io.h                      |   15 --
>  include/linux/kvm_host.h                |   37 ++--
>  include/linux/kvm_types.h               |    2 
>  include/linux/list.h                    |   17 ++
>  include/linux/memory_hotplug.h          |    3 
>  include/linux/mm.h                      |  310 ++++++++++++++++++++++++++++++-
>  include/linux/mm_types.h                |    5 +
>  include/linux/pfn.h                     |    9 +
>  kernel/memremap.c                       |  188 ++++++++++++++++++-
>  lib/list_debug.c                        |    4 
>  mm/gup.c                                |   18 ++
>  mm/huge_memory.c                        |  131 +++++++++----
>  mm/memory.c                             |   25 +--
>  mm/memory_hotplug.c                     |   66 +++++--
>  mm/mprotect.c                           |    5 -
>  mm/page_alloc.c                         |   10 +
>  mm/pgtable-generic.c                    |    2 
>  mm/sparse-vmemmap.c                     |   37 ++++
>  mm/sparse.c                             |    8 +
>  mm/swap.c                               |   15 ++
>  virt/kvm/kvm_main.c                     |   47 ++---
>  81 files changed, 1302 insertions(+), 417 deletions(-)
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm
> 

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Re: [PATCH -mm 00/25] get_user_pages() for dax pte and pmd mappings

[Dan Williams]

On Tue, Dec 8, 2015 at 10:42 AM, Logan Gunthorpe <logang@deltatee.com> wrote:
> Hi Dan,
>
> Perfect. This latest version of the patch set is once again passing all
> my tests without any issues.
>
> Tested-By: Logan Gunthorpe <logang@deltatee.com>
>
> Thanks,
>
> Logan

Thank you for the testing, Logan!

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