* [PATCH AUTOSEL 4.4 24/26] fs/drop_caches.c: avoid softlockups in drop_pagecache_sb()
[not found] <20190223211047.202725-1-sashal@kernel.org>
@ 2019-02-23 21:10 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2019-02-23 21:10 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Jan Kara, Al Viro, Andrew Morton, Linus Torvalds, Sasha Levin,
linux-fsdevel
From: Jan Kara <jack@suse.cz>
[ Upstream commit c27d82f52f75fc9d8d9d40d120d2a96fdeeada5e ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/drop_caches.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index d72d52b904333..280460fef0664 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -20,8 +20,13 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
spin_lock(&sb->s_inode_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
spin_lock(&inode->i_lock);
+ /*
+ * We must skip inodes in unusual state. We may also skip
+ * inodes without pages but we deliberately won't in case
+ * we need to reschedule to avoid softlockups.
+ */
if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
- (inode->i_mapping->nrpages == 0)) {
+ (inode->i_mapping->nrpages == 0 && !need_resched())) {
spin_unlock(&inode->i_lock);
continue;
}
@@ -29,6 +34,7 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
spin_unlock(&inode->i_lock);
spin_unlock(&sb->s_inode_list_lock);
+ cond_resched();
invalidate_mapping_pages(inode->i_mapping, 0, -1);
iput(toput_inode);
toput_inode = inode;
--
2.19.1
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2019-02-23 21:11 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
[not found] <20190223211047.202725-1-sashal@kernel.org>
2019-02-23 21:10 ` [PATCH AUTOSEL 4.4 24/26] fs/drop_caches.c: avoid softlockups in drop_pagecache_sb() Sasha Levin
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).