syzbot


INFO: task can't die in lock_downgrade
Status: moderation: reported on 2022/03/11 04:09
Reported-by: syzbot+c484b7eb0d0fb43faedc@syzkaller.appspotmail.com
First crash: 81d, last: 59d

Sample crash report:
INFO: task syz-executor.0:8571 can't die for more than 143 seconds.
task:syz-executor.0  state:R  running task     stack:24760 pid: 8571 ppid:  3626 flags:0x00004006
Call Trace:
 <TASK>
 lock_downgrade+0x6e0/0x6e0 kernel/locking/lockdep.c:5095
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/28:
 #0: ffffffff8bd82360 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6498
2 locks held by getty/3280:
 #0: ffff888148e23098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:244
 #1: ffffc90002e732e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xcea/0x1230 drivers/tty/n_tty.c:2075
2 locks held by kworker/u4:0/7671:
 #0: ffff8880b9c39f98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2b/0x120 kernel/sched/core.c:541
 #1: ffffc90003337da8 ((work_completion)(&(&bat_priv->nc.work)->work)){+.+.}-{0:0}, at: process_one_work+0x8ae/0x1610 kernel/workqueue.c:2264
2 locks held by syz-executor.0/8571:

=============================================

Kernel panic - not syncing: hung_task: blocked tasks
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 5.17.0-next-20220328-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 panic+0x2d7/0x636 kernel/panic.c:274
 check_hung_uninterruptible_tasks kernel/hung_task.c:260 [inline]
 watchdog.cold+0x1ca/0x1de kernel/hung_task.c:413
 kthread+0x2e9/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>
Kernel Offset: disabled
Rebooting in 86400 seconds..

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-linux-next-kasan-gce-root 2022/03/29 04:38 linux-next 8515d05bf6bc 6bdac766 .config log report info INFO: task can't die in lock_downgrade
ci-upstream-linux-next-kasan-gce-root 2022/03/07 04:01 linux-next 91265a6da44d 7bdd8b2c .config log report info INFO: task can't die in lock_downgrade