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e10e8f490d
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Andreas Gruenbacher e10e8f490d gfs2: Cancel remote delete work asynchronously 
[ Upstream commit 486408d690 ]

In gfs2_inode_lookup and gfs2_create_inode, we're calling
gfs2_cancel_delete_work which currently cancels any remote delete work
(delete_work_func) synchronously.  This means that if the work is
currently running, it will wait for it to finish.  We're doing this to
pevent a previous instance of an inode from having any influence on the
next instance.

However, delete_work_func uses gfs2_inode_lookup internally, and we can
end up in a deadlock when delete_work_func gets interrupted at the wrong
time.  For example,

  (1) An inode's iopen glock has delete work queued, but the inode
      itself has been evicted from the inode cache.

  (2) The delete work is preempted before reaching gfs2_inode_lookup.

  (3) Another process recreates the inode (gfs2_create_inode).  It tries
      to cancel any outstanding delete work, which blocks waiting for
      the ongoing delete work to finish.

  (4) The delete work calls gfs2_inode_lookup, which blocks waiting for
      gfs2_create_inode to instantiate and unlock the new inode =>
      deadlock.

It turns out that when the delete work notices that its inode has been
re-instantiated, it will do nothing.  This means that it's safe to
cancel the delete work asynchronously.  This prevents the kind of
deadlock described above.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-11-18 19:16:19 +01:00
arch ARM: clang: Do not rely on lr register for stacktrace 2021-11-18 19:16:19 +01:00
block block: remove inaccurate requeue check 2021-11-18 19:16:17 +01:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-08-30 12:57:10 -07:00
Documentation fscrypt: allow 256-bit master keys with AES-256-XTS 2021-11-18 19:16:11 +01:00
drivers can: bittiming: can_fixup_bittiming(): change type of tseg1 and alltseg to unsigned int 2021-11-18 19:16:19 +01:00
fs gfs2: Cancel remote delete work asynchronously 2021-11-18 19:16:19 +01:00
include block: bump max plugged deferred size from 16 to 32 2021-11-18 19:16:16 +01:00
init bootconfig: init: Fix memblock leak in xbc_make_cmdline() 2021-10-10 22:27:40 -04:00
ipc ipc: remove memcg accounting for sops objects in do_semtimedop() 2021-09-14 10:22:11 -07:00
kernel PM: hibernate: Get block device exclusively in swsusp_check() 2021-11-18 19:16:18 +01:00
lib lib/xz: Validate the value before assigning it to an enum variable 2021-11-18 19:16:17 +01:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm kfence: always use static branches to guard kfence_alloc() 2021-11-12 15:05:49 +01:00
net gre/sit: Don't generate link-local addr if addr_gen_mode is IN6_ADDR_GEN_MODE_NONE 2021-11-18 19:16:19 +01:00
samples samples/bpf: Fix application of sizeof to pointer 2021-11-18 19:16:18 +01:00
scripts leaking_addresses: Always print a trailing newline 2021-11-18 19:16:16 +01:00
security smackfs: use __GFP_NOFAIL for smk_cipso_doi() 2021-11-18 19:16:19 +01:00
sound ASoC: tegra: Restore AC97 support 2021-11-18 19:16:01 +01:00
tools selftests/bpf: Fix perf_buffer test on system with offline cpus 2021-11-18 19:16:18 +01:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Remove tlbs_dirty 2021-09-23 11:01:12 -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 Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
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 drm fixes for 5.15 final 2021-10-28 12:17:01 -07:00
Makefile Linux 5.15.2 2021-11-12 15:05:52 +01:00
README

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.