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Hugh Dickins 4dfa0d6f48 mm/thp: fix vma_address() if virtual address below file offset 
[ Upstream commit 494334e43c ]

Running certain tests with a DEBUG_VM kernel would crash within hours,
on the total_mapcount BUG() in split_huge_page_to_list(), while trying
to free up some memory by punching a hole in a shmem huge page: split's
try_to_unmap() was unable to find all the mappings of the page (which,
on a !DEBUG_VM kernel, would then keep the huge page pinned in memory).

When that BUG() was changed to a WARN(), it would later crash on the
VM_BUG_ON_VMA(end < vma->vm_start || start >= vma->vm_end, vma) in
mm/internal.h:vma_address(), used by rmap_walk_file() for
try_to_unmap().

vma_address() is usually correct, but there's a wraparound case when the
vm_start address is unusually low, but vm_pgoff not so low:
vma_address() chooses max(start, vma->vm_start), but that decides on the
wrong address, because start has become almost ULONG_MAX.

Rewrite vma_address() to be more careful about vm_pgoff; move the
VM_BUG_ON_VMA() out of it, returning -EFAULT for errors, so that it can
be safely used from page_mapped_in_vma() and page_address_in_vma() too.

Add vma_address_end() to apply similar care to end address calculation,
in page_vma_mapped_walk() and page_mkclean_one() and try_to_unmap_one();
though it raises a question of whether callers would do better to supply
pvmw->end to page_vma_mapped_walk() - I chose not, for a smaller patch.

An irritation is that their apparent generality breaks down on KSM
pages, which cannot be located by the page->index that page_to_pgoff()
uses: as commit 4b0ece6fa0 ("mm: migrate: fix remove_migration_pte()
for ksm pages") once discovered.  I dithered over the best thing to do
about that, and have ended up with a VM_BUG_ON_PAGE(PageKsm) in both
vma_address() and vma_address_end(); though the only place in danger of
using it on them was try_to_unmap_one().

Sidenote: vma_address() and vma_address_end() now use compound_nr() on a
head page, instead of thp_size(): to make the right calculation on a
hugetlbfs page, whether or not THPs are configured.  try_to_unmap() is
used on hugetlbfs pages, but perhaps the wrong calculation never
mattered.

Link: https://lkml.kernel.org/r/caf1c1a3-7cfb-7f8f-1beb-ba816e932825@google.com
Fixes: a8fa41ad2f ("mm, rmap: check all VMAs that PTE-mapped THP can be part of")
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jue Wang <juew@google.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Wang Yugui <wangyugui@e16-tech.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Note on stable backport: fixed up conflicts on intervening thp_size(),
and mmu_notifier_range initializations; substitute for compound_nr().

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-07-11 12:48:10 +02:00
arch arm64: perf: Disable PMU while processing counter overflows 2021-06-30 08:48:56 -04:00
block blk-mq: Swap two calls in blk_mq_exit_queue() 2021-05-22 10:57:40 +02:00
certs certs: Fix blacklist flag type confusion 2021-03-03 18:22:46 +01:00
crypto crypto: api - check for ERR pointers in crypto_destroy_tfm() 2021-05-22 10:57:16 +02:00
Documentation tweewide: Fix most Shebang lines 2021-06-03 08:36:11 +02:00
drivers i2c: robotfuzz-osif: fix control-request directions 2021-06-30 08:48:59 -04:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:20:30 +01:00
fs nilfs2: fix memory leak in nilfs_sysfs_delete_device_group 2021-06-30 08:48:59 -04:00
include mm/thp: try_to_unmap() use TTU_SYNC for safe splitting 2021-07-11 12:48:10 +02:00
init pid: take a reference when initializing cad_pid 2021-06-10 12:43:51 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:17:07 +02:00
kernel tracing: Do no increment trace_clock_global() by one 2021-06-30 08:48:53 -04:00
lib lib: stackdepot: turn depot_lock spinlock to raw_spinlock 2021-05-22 10:57:43 +02:00
mm mm/thp: fix vma_address() if virtual address below file offset 2021-07-11 12:48:10 +02:00
net net/packet: annotate accesses to po->ifindex 2021-06-30 08:48:58 -04:00
samples samples/bpf: Fix broken tracex1 due to kprobe argument change 2021-05-22 10:57:37 +02:00
scripts scripts: switch explicitly to Python 3 2021-06-03 08:36:11 +02:00
security security: commoncap: fix -Wstringop-overread warning 2021-05-22 10:57:21 +02:00
sound ASoC: sti-sas: add missing MODULE_DEVICE_TABLE 2021-06-16 11:53:00 +02:00
tools perf session: Correct buffer copying when peeking events 2021-06-16 11:53:04 +02:00
usr initramfs: restore default compression behavior 2020-04-13 10:34:19 +02:00
virt KVM: arm64: Fix exclusive limit for IPA size 2021-03-17 16:34:35 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 16:36:12 +01:00
Makefile Linux 4.14.238 2021-06-30 09:21:52 -04:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.