5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 3e7917c0cdad835a5121520fc5686d954b7a61ab ]
linkwatch_event() grabs possibly very contended RTNL mutex.
system_wq is not suitable for such work.
Inspired by many noisy syzbot reports.
3 locks held by kworker/0:7/5266:
#0: ffff888015480948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3206 [inline]
#0: ffff888015480948 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0x90a/0x1830 kernel/workqueue.c:3312
#1: ffffc90003f6fd00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3207 [inline]
, at: process_scheduled_works+0x945/0x1830 kernel/workqueue.c:3312
#2: ffffffff8fa6f208 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:276
Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Link: https://patch.msgid.link/20240805085821.1616528-1-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/core/link_watch.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/core/link_watch.c b/net/core/link_watch.c
index 35b0e39030daf..a70b2adc47a16 100644
--- a/net/core/link_watch.c
+++ b/net/core/link_watch.c
@@ -130,9 +130,9 @@ static void linkwatch_schedule_work(int urgent)
* override the existing timer.
*/
if (test_bit(LW_URGENT, &linkwatch_flags))
- mod_delayed_work(system_wq, &linkwatch_work, 0);
+ mod_delayed_work(system_unbound_wq, &linkwatch_work, 0);
else
- schedule_delayed_work(&linkwatch_work, delay);
+ queue_delayed_work(system_unbound_wq, &linkwatch_work, delay);
}
--
2.43.0
