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linux-stable/fs/notify
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Amir Goldstein cd57645223 fsnotify: fix wrong lockdep annotations 
[ Upstream commit 623af4f538 ]

Commit 6960b0d909 ("fsnotify: change locking order") changed some
of the mark_mutex locks in direct reclaim path to use:
  mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);

This change is explained:
 "...It uses nested locking to avoid deadlock in case we do the final
  iput() on an inode which still holds marks and thus would take the
  mutex again when calling fsnotify_inode_delete() in destroy_inode()."

The problem is that the mutex_lock_nested() is not a nested lock at
all. In fact, it has the opposite effect of preventing lockdep from
warning about a very possible deadlock.

Due to these wrong annotations, a deadlock that was introduced with
nfsd filecache in kernel v5.4 went unnoticed in v5.4.y for over two
years until it was reported recently by Khazhismel Kumykov, only to
find out that the deadlock was already fixed in kernel v5.5.

Fix the wrong lockdep annotations.

Cc: Khazhismel Kumykov <khazhy@google.com>
Fixes: 6960b0d909 ("fsnotify: change locking order")
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/
Link: https://lore.kernel.org/r/20220422120327.3459282-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2022-06-14 16:53:48 +02:00
..
dnotify dnotify: Handle errors from fsnotify_add_mark_locked() in fcntl_dirnotify() 2018-02-25 11:07:47 +01:00
fanotify fanotify: fix logic of events on child 2018-04-24 09:36:38 +02:00
inotify inotify: show inotify mask flags in proc fdinfo 2022-06-14 16:53:48 +02:00
Kconfig
…
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fdinfo.c inotify: show inotify mask flags in proc fdinfo 2022-06-14 16:53:48 +02:00
fdinfo.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fsnotify.c fs: avoid softlockups in s_inodes iterators 2020-01-12 12:11:59 +01:00
fsnotify.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
group.c fsnotify: Remove fsnotify_detach_group_marks() 2017-04-10 17:37:36 +02:00
mark.c fsnotify: fix wrong lockdep annotations 2022-06-14 16:53:48 +02:00
notification.c
…