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Miaohe Lin 2799e77529 swap: fix do_swap_page() race with swapoff 
When I was investigating the swap code, I found the below possible race
window:

CPU 1                                   	CPU 2
-----                                   	-----
do_swap_page
  if (data_race(si->flags & SWP_SYNCHRONOUS_IO)
  swap_readpage
    if (data_race(sis->flags & SWP_FS_OPS)) {
                                        	swapoff
					  	  ..
					  	  p->swap_file = NULL;
					  	  ..
    struct file *swap_file = sis->swap_file;
    struct address_space *mapping = swap_file->f_mapping;[oops!]

Note that for the pages that are swapped in through swap cache, this isn't
an issue. Because the page is locked, and the swap entry will be marked
with SWAP_HAS_CACHE, so swapoff() can not proceed until the page has been
unlocked.

Fix this race by using get/put_swap_device() to guard against concurrent
swapoff.

Link: https://lkml.kernel.org/r/20210426123316.806267-3-linmiaohe@huawei.com
Fixes: 0bcac06f27 ("mm,swap: skip swapcache for swapin of synchronous device")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-06-29 10:53:49 -07:00
arch ia64: mca_drv: fix incorrect array size calculation 2021-06-29 10:53:45 -07:00
block block-5.13-2021-05-22 2021-05-22 07:40:34 -10:00
certs Kbuild updates for v5.13 (2nd) 2021-05-08 10:00:11 -07:00
crypto async_xor: check src_offs is not NULL before updating it 2021-06-10 19:40:14 -07:00
Documentation mm/page_reporting: export reporting order as module parameter 2021-06-29 10:53:47 -07:00
drivers fs: remove noop_set_page_dirty() 2021-06-29 10:53:48 -07:00
fs mm: gup: pack has_pinned in MMF_HAS_PINNED 2021-06-29 10:53:48 -07:00
include swap: fix do_swap_page() race with swapoff 2021-06-29 10:53:49 -07:00
init pid: take a reference when initializing cad_pid 2021-06-05 08:58:11 -07:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-22 15:09:07 -10:00
kernel mm: gup: pack has_pinned in MMF_HAS_PINNED 2021-06-29 10:53:48 -07:00
lib slub: force on no_hash_pointers when slub_debug is enabled 2021-06-29 10:53:47 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm swap: fix do_swap_page() race with swapoff 2021-06-29 10:53:49 -07:00
net libceph: set global_id as soon as we get an auth ticket 2021-06-24 21:03:17 +02:00
samples VFIO fixes for v5.13-rc5 2021-06-03 11:52:24 -07:00
scripts scripts/spelling.txt: add more spellings to spelling.txt 2021-06-29 10:53:45 -07:00
security trusted-keys: match tpm_get_ops on all return paths 2021-05-12 22:36:37 +03:00
sound ASoC: rt5645: Avoid upgrading static warnings to errors 2021-06-24 12:22:27 +02:00
tools mm/gup_benchmark: support threading 2021-06-29 10:53:48 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: do not allow mapping valid but non-reference-counted pages 2021-06-24 11:55:11 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Marek's other e-mail address and identity without diacritics 2021-06-24 19:40:54 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge branch 'akpm' (patches from Andrew) 2021-06-25 11:05:03 -07:00
Makefile Linux 5.13 2021-06-27 15:21:11 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.