From: Dan Williams <dan.j.williams@intel.com>
To: linux-kernel@vger.kernel.org
Cc: axboe@kernel.dk, riel@redhat.com, linux-nvdimm@ml01.01.org,
linux-mm@kvack.org, mgorman@suse.de,
torvalds@linux-foundation.org, hch@lst.de
Subject: [PATCH v5 0/5] introduce __pfn_t for unmapped pfn I/O and DAX lifetime
Date: Wed, 12 Aug 2015 23:00:59 -0400 [thread overview]
Message-ID: <20150813025112.36703.21333.stgit@otcpl-skl-sds-2.jf.intel.com> (raw)
Changes since v4 [1]:
1/ Allow up to PAGE_SHIFT bits in PFN_ flags. Previously the __pfn_t
value was a union with a 'struct page *', but now __pfn_t_to_page()
internally does a pfn_to_page() instead of type-punning the value.
(Linus, Matthew)
2/ Move the definition to include/linux/mm.h and squash the
kmap_atomic_pfn_t() definition into the same patch. (Christoph)
3/ Kill dax_get_pfn(). Now replaced with dax_map_bh() (Matthew)
4/ The scatterlist cleanup patches are moved to their own series being
carried by Christoph.
[1]: https://lists.01.org/pipermail/linux-nvdimm/2015-June/001094.html
---
We want persistent memory to have 4 modes of access:
1/ Block device: persistent memory treated as a ram disk (done)
2/ DAX: userspace mmap (done)
3/ Kernel "page-less". (this series)
4/ Kernel and userspace references to page-mapped persistent memory
(future series)
The "kernel 'page-less'" case leverages the fact that a 'struct page'
object is not necessarily required for describing a DMA transfer from a
device to a persistent memory address. A pfn will do, but code needs to
be careful to not perform a pfn_to_page() operation on unmapped
persistent memory. The __pfn_t type enforces that safety and
kmap_atomic_pfn_t() covers cases where the I/O stack needs to touch the
buffer on its way to the low-level-device-driver (i.e. current usages of
kmap_atomic() in the block-layer).
A subsequent patch series will add struct page coverage for persistent,
"device", memory.
We also use kmap_atomic_pfn_t() to solve races of pmem driver unbind vs
usage in DAX. rcu_read_lock() protects the driver from unbinding while a
mapping is held.
---
Christoph Hellwig (1):
mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h
Dan Williams (4):
allow mapping page-less memremaped areas into KVA
dax: drop size parameter to ->direct_access()
dax: fix mapping lifetime handling, convert to __pfn_t + kmap_atomic_pfn_t()
scatterlist: convert to __pfn_t
arch/arm/include/asm/memory.h | 6 --
arch/arm64/include/asm/memory.h | 6 --
arch/powerpc/platforms/Kconfig | 1
arch/powerpc/sysdev/axonram.c | 24 +++++--
arch/unicore32/include/asm/memory.h | 6 --
drivers/block/brd.c | 9 +--
drivers/nvdimm/Kconfig | 1
drivers/nvdimm/pmem.c | 24 ++++---
drivers/s390/block/Kconfig | 1
drivers/s390/block/dcssblk.c | 23 ++++++-
fs/Kconfig | 1
fs/block_dev.c | 4 +
fs/dax.c | 79 +++++++++++++++++-------
include/asm-generic/memory_model.h | 6 ++
include/linux/blkdev.h | 7 +-
include/linux/kmap_pfn.h | 31 +++++++++
include/linux/mm.h | 78 +++++++++++++++++++++++
include/linux/scatterlist.h | 111 +++++++++++++++++++++++----------
mm/Kconfig | 3 +
mm/Makefile | 1
mm/kmap_pfn.c | 117 +++++++++++++++++++++++++++++++++++
samples/kfifo/dma-example.c | 8 +-
22 files changed, 435 insertions(+), 112 deletions(-)
create mode 100644 include/linux/kmap_pfn.h
create mode 100644 mm/kmap_pfn.c
next reply other threads:[~2015-08-13 3:06 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-13 3:00 Dan Williams [this message]
2015-08-13 3:01 ` [PATCH v5 1/5] mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h Dan Williams
2015-08-13 3:01 ` [PATCH v5 2/5] allow mapping page-less memremaped areas into KVA Dan Williams
2015-08-13 5:58 ` Boaz Harrosh
2015-08-13 12:57 ` Dan Williams
2015-08-13 13:23 ` Boaz Harrosh
2015-08-13 14:41 ` Christoph Hellwig
2015-08-13 15:01 ` Boaz Harrosh
2015-08-13 14:37 ` Christoph Hellwig
2015-08-13 14:48 ` Boaz Harrosh
2015-08-13 15:29 ` Boaz Harrosh
2015-08-13 17:37 ` Dave Hansen
2015-08-13 17:35 ` Matthew Wilcox
2015-08-13 18:15 ` Dan Williams
2015-08-13 3:01 ` [PATCH v5 3/5] dax: drop size parameter to ->direct_access() Dan Williams
2015-08-13 3:01 ` [PATCH v5 4/5] dax: fix mapping lifetime handling, convert to __pfn_t + kmap_atomic_pfn_t() Dan Williams
2015-08-13 6:26 ` Boaz Harrosh
2015-08-13 15:21 ` Dan Williams
2015-08-13 16:34 ` Boaz Harrosh
2015-08-13 18:51 ` Dan Williams
2015-08-13 3:01 ` [PATCH v5 5/5] scatterlist: convert to __pfn_t Dan Williams
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