linux/fs/notify
Amir Goldstein 623af4f538 fsnotify: fix wrong lockdep annotations
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>
2022-04-25 14:37:08 +02:00
..
dnotify dnotify: move dnotify sysctl to dnotify.c 2022-01-22 08:33:34 +02:00
fanotify fsnotify: optimize FS_MODIFY events with no ignored masks 2022-02-24 14:05:18 +01:00
inotify inotify: move control flags from mask to mark flags 2022-04-25 14:37:06 +02:00
fdinfo.c inotify: show inotify mask flags in proc fdinfo 2022-04-25 14:37:03 +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 inotify: move control flags from mask to mark flags 2022-04-25 14:37:06 +02:00
fsnotify.h fsnotify: count all objects with attached connectors 2021-08-11 13:50:48 +02:00
group.c fsnotify: clarify object type argument 2021-12-15 14:04:03 +01:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mark.c fsnotify: fix wrong lockdep annotations 2022-04-25 14:37:08 +02:00
notification.c fsnotify: Pass group argument to free_event 2021-10-27 12:34:18 +02:00