6.10-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 8ec35194bfcb8..ab150641142aa 100644 --- a/net/core/link_watch.c +++ b/net/core/link_watch.c @@ -148,9 +148,9 @@ 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