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Gang Li 7b9fa915a5 shmem: fix a race between shmem_unused_huge_shrink and shmem_evict_inode 
commit 62c9827cbb996c2c04f615ecd783ce28bcea894b upstream.

Fix a data race in commit 779750d20b ("shmem: split huge pages beyond
i_size under memory pressure").

Here are call traces causing race:

   Call Trace 1:
     shmem_unused_huge_shrink+0x3ae/0x410
     ? __list_lru_walk_one.isra.5+0x33/0x160
     super_cache_scan+0x17c/0x190
     shrink_slab.part.55+0x1ef/0x3f0
     shrink_node+0x10e/0x330
     kswapd+0x380/0x740
     kthread+0xfc/0x130
     ? mem_cgroup_shrink_node+0x170/0x170
     ? kthread_create_on_node+0x70/0x70
     ret_from_fork+0x1f/0x30

   Call Trace 2:
     shmem_evict_inode+0xd8/0x190
     evict+0xbe/0x1c0
     do_unlinkat+0x137/0x330
     do_syscall_64+0x76/0x120
     entry_SYSCALL_64_after_hwframe+0x3d/0xa2

A simple explanation:

Image there are 3 items in the local list (@list).  In the first
traversal, A is not deleted from @list.

  1)    A->B->C
        ^
        |
        pos (leave)

In the second traversal, B is deleted from @list.  Concurrently, A is
deleted from @list through shmem_evict_inode() since last reference
counter of inode is dropped by other thread.  Then the @list is corrupted.

  2)    A->B->C
        ^  ^
        |  |
     evict pos (drop)

We should make sure the inode is either on the global list or deleted from
any local list before iput().

Fixed by moving inodes back to global list before we put them.

[akpm@linux-foundation.org: coding style fixes]

Link: https://lkml.kernel.org/r/20211125064502.99983-1-ligang.bdlg@bytedance.com
Fixes: 779750d20b ("shmem: split huge pages beyond i_size under memory pressure")
Signed-off-by: Gang Li <ligang.bdlg@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-01-27 10:53:44 +01:00
arch x86/gpu: Reserve stolen memory for first integrated Intel GPU 2022-01-27 10:53:41 +01:00
block iocost: Fix divide-by-zero on donation from low hweight cgroup 2021-12-22 09:30:57 +01:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: pcrypt - Delay write to padata->info 2021-11-18 14:04:12 +01:00
Documentation bpf: Add kconfig knob for disabling unpriv bpf by default 2022-01-05 12:40:34 +01:00
drivers PCI: Add function 1 DMA alias quirk for Marvell 88SE9125 SATA controller 2022-01-27 10:53:43 +01:00
fs f2fs: fix to do sanity check in is_alive() 2022-01-27 10:53:41 +01:00
include mm_zone: add function to check if managed dma zone exists 2022-01-27 10:53:44 +01:00
init bpf: Add kconfig knob for disabling unpriv bpf by default 2022-01-05 12:40:34 +01:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:19:10 +01:00
kernel dma/pool: create dma atomic pool only if dma zone has managed pages 2022-01-27 10:53:44 +01:00
lib siphash: use _unaligned version by default 2021-12-08 09:03:23 +01:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm shmem: fix a race between shmem_unused_huge_shrink and shmem_evict_inode 2022-01-27 10:53:44 +01:00
net nfc: llcp: fix NULL error pointer dereference on sendmsg() after failed bind() 2022-01-27 10:53:41 +01:00
samples ftrace/samples: Add missing prototypes direct functions 2022-01-11 15:25:00 +01:00
scripts recordmcount.pl: fix typo in s390 mcount regex 2022-01-05 12:40:29 +01:00
security selinux: initialize proto variable in selinux_ip_postroute_compat() 2022-01-05 12:40:30 +01:00
sound ALSA: hda/realtek: Re-order quirk entries for Lenovo 2022-01-20 09:17:51 +01:00
tools tools/nolibc: fix incorrect truncation of exit code 2022-01-27 10:53:42 +01:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: downgrade two BUG_ONs to WARN_ON_ONCE 2021-12-22 09:30:50 +01:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
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 MAINTAINERS: adjust GCC PLUGINS after gcc-plugin.sh removal 2021-12-14 11:32:46 +01:00
Makefile Linux 5.10.93 2022-01-20 09:17:52 +01:00
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.