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Ryan Roberts 426931e7e5 mm: ptdump should use ptep_get_lockless()
Patch series "Encapsulate PTE contents from non-arch code", v3.

A series to improve the encapsulation of pte entries by disallowing
non-arch code from directly dereferencing pte_t pointers.

This means that by default, the accesses change from a C dereference to a
READ_ONCE().  This is technically the correct thing to do since where
pgtables are modified by HW (for access/dirty) they are volatile and
therefore we should always ensure READ_ONCE() semantics.

But more importantly, by always using the helper, it can be overridden by
the architecture to fully encapsulate the contents of the pte.  Arch code
is deliberately not converted, as the arch code knows best.  It is
intended that arch code (arm64) will override the default with its own
implementation that can (e.g.) hide certain bits from the core code, or
determine young/dirty status by mixing in state from another source.


This patch (of 3):

The page table dumper uses walk_page_range_novma() to walk the page
tables, which does not lock the PTL before calling the pte_entry()
callback.  Therefore, the page table dumper's callback must use
ptep_get_lockless() rather than ptep_get() to ensure that the pte it reads
is not torn or otherwise corrupt when racing with writers.

Link: https://lkml.kernel.org/r/20230612151545.3317766-1-ryan.roberts@arm.com
Link: https://lkml.kernel.org/r/20230612151545.3317766-2-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-06-19 16:19:24 -07:00
arch sh: move the ARCH_DMA_MINALIGN definition to asm/cache.h 2023-06-19 16:19:24 -07:00
block filemap: add a kiocb_write_and_wait helper 2023-06-09 16:25:52 -07:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto This push fixes the following problems: 2023-05-07 10:57:14 -07:00
Documentation mm/pgtable: allow pte_offset_map[_lock]() to fail 2023-06-19 16:19:12 -07:00
drivers iommu/dma: force bouncing if the size is not cacheline-aligned 2023-06-19 16:19:23 -07:00
fs mm/userfaultfd: retry if pte_offset_map() fails 2023-06-19 16:19:15 -07:00
include iommu/dma: force bouncing if the size is not cacheline-aligned 2023-06-19 16:19:23 -07:00
init cachestat: implement cachestat syscall 2023-06-09 16:25:16 -07:00
io_uring mm/gup: remove vmas parameter from pin_user_pages() 2023-06-09 16:25:26 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel dma-mapping: force bouncing if the kmalloc() size is not cache-line-aligned 2023-06-19 16:19:23 -07:00
lib maple_tree: simplify and clean up mas_wr_node_store() 2023-06-09 16:25:45 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: ptdump should use ptep_get_lockless() 2023-06-19 16:19:24 -07:00
net mm/gup: remove vmas parameter from pin_user_pages() 2023-06-09 16:25:26 -07:00
rust Rust changes for v6.4 2023-04-30 11:20:22 -07:00
samples kmemleak-test: drop __init to get better backtrace 2023-06-09 16:25:40 -07:00
scripts Locking changes in v6.4: 2023-05-05 12:56:55 -07:00
security mm/gup: remove vmas parameter from get_user_pages_remote() 2023-06-09 16:25:26 -07:00
sound ALSA: hda/realtek: Enable headset onLenovo M70/M90 2023-05-24 14:18:59 +02:00
tools selftests: damon: add config file 2023-06-19 16:19:11 -07:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt mm/gup: remove vmas parameter from get_user_pages_remote() 2023-06-09 16:25:26 -07:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Nikolay Aleksandrov 2023-05-17 09:35:05 +01:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS selftests: add selftests for cachestat 2023-06-09 16:25:17 -07:00
Makefile Linux 6.4-rc4 2023-05-28 07:49:00 -04:00
README

Linux kernel
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There are several guides for kernel developers and users. These guides can
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Please read the Documentation/process/changes.rst file, as it contains the
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the problems which may result by upgrading your kernel.