fs/drop_caches.c: avoid softlockups in drop_pagecache_sb()
authorJan Kara <jack@suse.cz>
Fri, 1 Feb 2019 22:21:23 +0000 (14:21 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 1 Feb 2019 23:46:24 +0000 (15:46 -0800)
commitc27d82f52f75fc9d8d9d40d120d2a96fdeeada5e
tree0151720bb1ba96e8ce742674b96bef291b43fce5
parente0a352fabce61f730341d119fbedf71ffdb8663f
fs/drop_caches.c: avoid softlockups in drop_pagecache_sb()

When superblock has lots of inodes without any pagecache (like is the
case for /proc), drop_pagecache_sb() will iterate through all of them
without dropping sb->s_inode_list_lock which can lead to softlockups
(one of our customers hit this).

Fix the problem by going to the slow path and doing cond_resched() in
case the process needs rescheduling.

Link: http://lkml.kernel.org/r/20190114085343.15011-1-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/drop_caches.c