[PATCH V4 0/3] arm64: Enable vmemmap mapping from device memory

[PATCH V4 0/3] arm64: Enable vmemmap mapping from device memory

[Anshuman Khandual]

This series enables vmemmap backing memory allocation from device memory
ranges on arm64. But before that, it enables vmemmap_populate_basepages()
and vmemmap_alloc_block_buf() to accommodate struct vmem_altmap based
alocation requests.

This series applies on 5.8-rc4.

Changes in V4:

- Dropped 'fallback' from vmemmap_alloc_block_buf() per Catalin

Changes in V3: (https://patchwork.kernel.org/project/linux-mm/list/?series=304707)

- Dropped comment from free_hotplug_page_range() per Robin
- Modified comment in unmap_hotplug_range() per Robin
- Enabled altmap support in vmemmap_alloc_block_buf() per Robin

Changes in V2: (https://lkml.org/lkml/2020/3/4/475)

- Rebased on latest hot-remove series (v14) adding P4D page table support

Changes in V1: (https://lkml.org/lkml/2020/1/23/12)

- Added an WARN_ON() in unmap_hotplug_range() when altmap is
  provided without the page table backing memory being freed

Changes in RFC V2: (https://lkml.org/lkml/2019/10/21/11)

- Changed the commit message on 1/2 patch per Will
- Changed the commit message on 2/2 patch as well
- Rebased on arm64 memory hot remove series (v10)

RFC V1: (https://lkml.org/lkml/2019/6/28/32)

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-riscv@lists.infradead.org
Cc: x86@kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org


Anshuman Khandual (3):
  mm/sparsemem: Enable vmem_altmap support in vmemmap_populate_basepages()
  mm/sparsemem: Enable vmem_altmap support in vmemmap_alloc_block_buf()
  arm64/mm: Enable vmem_altmap support for vmemmap mappings

 Documentation/vm/memory-model.rst |  2 +-
 arch/arm64/mm/mmu.c               | 58 ++++++++++++++++++++-----------
 arch/ia64/mm/discontig.c          |  2 +-
 arch/powerpc/mm/init_64.c         |  4 +--
 arch/riscv/mm/init.c              |  2 +-
 arch/x86/mm/init_64.c             | 11 +++---
 include/linux/mm.h                |  9 ++---
 mm/sparse-vmemmap.c               | 36 ++++++++++---------
 8 files changed, 72 insertions(+), 52 deletions(-)

-- 
2.20.1

[PATCH V4 2/3] mm/sparsemem: Enable vmem_altmap support in vmemmap_alloc_block_buf()

[Anshuman Khandual]

There are many instances where vmemap allocation is often switched between
regular memory and device memory just based on whether altmap is available
or not. vmemmap_alloc_block_buf() is used in various platforms to allocate
vmemmap mappings. Lets also enable it to handle altmap based device memory
allocation along with existing regular memory allocations. This will help
in avoiding the altmap based allocation switch in many places. To summarize
there are two different methods to call vmemmap_alloc_block_buf().

vmemmap_alloc_block_buf(size, node, NULL)   /* Allocate from system RAM */
vmemmap_alloc_block_buf(size, node, altmap) /* Allocate from altmap */

This converts altmap_alloc_block_buf() into a static function, drops it's
entry from the header and updates Documentation/vm/memory-model.rst.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-doc@vger.kernel.org
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Tested-by: Jia He <justin.he@arm.com>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
 Documentation/vm/memory-model.rst |  2 +-
 arch/arm64/mm/mmu.c               |  2 +-
 arch/powerpc/mm/init_64.c         |  4 ++--
 arch/x86/mm/init_64.c             |  5 +----
 include/linux/mm.h                |  4 ++--
 mm/sparse-vmemmap.c               | 28 +++++++++++++---------------
 6 files changed, 20 insertions(+), 25 deletions(-)

diff --git a/Documentation/vm/memory-model.rst b/Documentation/vm/memory-model.rst
index 91228044ed16..f26142cf24f2 100644
--- a/Documentation/vm/memory-model.rst
+++ b/Documentation/vm/memory-model.rst
@@ -178,7 +178,7 @@ for persistent memory devices in pre-allocated storage on those
 devices. This storage is represented with :c:type:`struct vmem_altmap`
 that is eventually passed to vmemmap_populate() through a long chain
 of function calls. The vmemmap_populate() implementation may use the
-`vmem_altmap` along with :c:func:`altmap_alloc_block_buf` helper to
+`vmem_altmap` along with :c:func:`vmemmap_alloc_block_buf` helper to
 allocate memory map on the persistent memory device.
 
 ZONE_DEVICE
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 63b74fd56cd8..9c08d1882106 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1101,7 +1101,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 		if (pmd_none(READ_ONCE(*pmdp))) {
 			void *p = NULL;
 
-			p = vmemmap_alloc_block_buf(PMD_SIZE, node);
+			p = vmemmap_alloc_block_buf(PMD_SIZE, node, NULL);
 			if (!p)
 				return -ENOMEM;
 
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index bc73abf0bc25..3fd504d72c5e 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -225,12 +225,12 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
 		 * fall back to system memory if the altmap allocation fail.
 		 */
 		if (altmap && !altmap_cross_boundary(altmap, start, page_size)) {
-			p = altmap_alloc_block_buf(page_size, altmap);
+			p = vmemmap_alloc_block_buf(page_size, node, altmap);
 			if (!p)
 				pr_debug("altmap block allocation failed, falling back to system memory");
 		}
 		if (!p)
-			p = vmemmap_alloc_block_buf(page_size, node);
+			p = vmemmap_alloc_block_buf(page_size, node, NULL);
 		if (!p)
 			return -ENOMEM;
 
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 19c0ed3271a3..5a7a45e7c5ea 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1463,10 +1463,7 @@ static int __meminit vmemmap_populate_hugepages(unsigned long start,
 		if (pmd_none(*pmd)) {
 			void *p;
 
-			if (altmap)
-				p = altmap_alloc_block_buf(PMD_SIZE, altmap);
-			else
-				p = vmemmap_alloc_block_buf(PMD_SIZE, node);
+			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
 			if (p) {
 				pte_t entry;
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e40ac543d248..1973872ed3ab 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3015,8 +3015,8 @@ pte_t *vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
 			    struct vmem_altmap *altmap);
 void *vmemmap_alloc_block(unsigned long size, int node);
 struct vmem_altmap;
-void *vmemmap_alloc_block_buf(unsigned long size, int node);
-void *altmap_alloc_block_buf(unsigned long size, struct vmem_altmap *altmap);
+void *vmemmap_alloc_block_buf(unsigned long size, int node,
+			      struct vmem_altmap *altmap);
 void vmemmap_verify(pte_t *, int, unsigned long, unsigned long);
 int vmemmap_populate_basepages(unsigned long start, unsigned long end,
 			       int node, struct vmem_altmap *altmap);
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index ceed10dec31e..41eeac67723b 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -69,11 +69,19 @@ void * __meminit vmemmap_alloc_block(unsigned long size, int node)
 				__pa(MAX_DMA_ADDRESS));
 }
 
+static void * __meminit altmap_alloc_block_buf(unsigned long size,
+					       struct vmem_altmap *altmap);
+
 /* need to make sure size is all the same during early stage */
-void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
+void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node,
+					 struct vmem_altmap *altmap)
 {
-	void *ptr = sparse_buffer_alloc(size);
+	void *ptr;
+
+	if (altmap)
+		return altmap_alloc_block_buf(size, altmap);
 
+	ptr = sparse_buffer_alloc(size);
 	if (!ptr)
 		ptr = vmemmap_alloc_block(size, node);
 	return ptr;
@@ -94,15 +102,8 @@ static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
 	return 0;
 }
 
-/**
- * altmap_alloc_block_buf - allocate pages from the device page map
- * @altmap:	device page map
- * @size:	size (in bytes) of the allocation
- *
- * Allocations are aligned to the size of the request.
- */
-void * __meminit altmap_alloc_block_buf(unsigned long size,
-		struct vmem_altmap *altmap)
+static void * __meminit altmap_alloc_block_buf(unsigned long size,
+					       struct vmem_altmap *altmap)
 {
 	unsigned long pfn, nr_pfns, nr_align;
 
@@ -147,10 +148,7 @@ pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
 		pte_t entry;
 		void *p;
 
-		if (altmap)
-			p = altmap_alloc_block_buf(PAGE_SIZE, altmap);
-		else
-			p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
+		p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
 		if (!p)
 			return NULL;
 		entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
-- 
2.20.1

Re: [PATCH V4 2/3] mm/sparsemem: Enable vmem_altmap support in vmemmap_alloc_block_buf()

[Catalin Marinas]

On Mon, Jul 06, 2020 at 08:26:17AM +0530, Anshuman Khandual wrote:
> There are many instances where vmemap allocation is often switched between
> regular memory and device memory just based on whether altmap is available
> or not. vmemmap_alloc_block_buf() is used in various platforms to allocate
> vmemmap mappings. Lets also enable it to handle altmap based device memory
> allocation along with existing regular memory allocations. This will help
> in avoiding the altmap based allocation switch in many places. To summarize
> there are two different methods to call vmemmap_alloc_block_buf().
> 
> vmemmap_alloc_block_buf(size, node, NULL)   /* Allocate from system RAM */
> vmemmap_alloc_block_buf(size, node, altmap) /* Allocate from altmap */
> 
> This converts altmap_alloc_block_buf() into a static function, drops it's

s/it's/its/

> entry from the header and updates Documentation/vm/memory-model.rst.
> 
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-doc@vger.kernel.org
> Cc: x86@kernel.org
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Tested-by: Jia He <justin.he@arm.com>
> Suggested-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>

With the fallback argument dropped, the patch looks fine to me.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH V4 0/3] arm64: Enable vmemmap mapping from device memory

[Anshuman Khandual]

On 07/06/2020 08:26 AM, Anshuman Khandual wrote:
> This series enables vmemmap backing memory allocation from device memory
> ranges on arm64. But before that, it enables vmemmap_populate_basepages()
> and vmemmap_alloc_block_buf() to accommodate struct vmem_altmap based
> alocation requests.
> 
> This series applies on 5.8-rc4.
> 
> Changes in V4:
> 
> - Dropped 'fallback' from vmemmap_alloc_block_buf() per Catalin

Hello Andrew,

This series has been a long running one :) Now that all the three patches
here have been reviewed, could you please consider this series for merging
towards 5.9-rc1. Catalin had suggested earlier [1] that it should go via
the MM tree instead, as it touches multiple architecture. Thank you.

[1] https://patchwork.kernel.org/patch/11611103/

- Anshuman