syzbot


INFO: task hung in io_sq_thread_park (2)
Status: fixed on 2021/11/10 00:50
Reported-by: syzbot+ac957324022b7132accf@syzkaller.appspotmail.com
Fix commit: 46fee9ab02cb io_uring: remove double poll entry on arm failure
First crash: 314d, last: 314d

Cause bisection: introduced by (bisect log) :
commit 4d004099a668c41522242aa146a38cc4eb59cb1e
Author: Peter Zijlstra <peterz@infradead.org>
Date: Fri Oct 2 09:04:21 2020 +0000

  lockdep: Fix lockdep recursion

Crash: BUG: using __this_cpu_read() in preemptible code in trace_hardirqs_on (log)
Repro: syz .config
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in io_sq_thread_park (3) 1 169d 169d 0/22 auto-closed as invalid on 2022/04/01 18:56
upstream INFO: task hung in io_sq_thread_park C unreliable 263 441d 446d 22/22 fixed on 2021/04/09 19:46
Patch testing requests:
Created Duration User Patch Repo Result
2021/07/19 16:57 16m asml.silence@gmail.com https://github.com/isilence/linux.git syztest_sqpoll_hang OK
2021/07/19 13:15 12m asml.silence@gmail.com https://github.com/isilence/linux.git syztest_sqpoll_hang report log
2021/07/16 10:38 16m asml.silence@gmail.com https://github.com/isilence/linux.git syztest_sqpoll_hang report log
2021/07/15 18:16 13m asml.silence@gmail.com https://github.com/isilence/linux.git syztest_sqpoll_hang report log
2021/07/15 08:44 15m asml.silence@gmail.com git://git.kernel.dk/linux-block io_uring-5.14 report log

Sample crash report:
INFO: task kworker/u4:4:9930 blocked for more than 143 seconds.
      Not tainted 5.13.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:4    state:D stack:25664 pid: 9930 ppid:     2 flags:0x00004000
Workqueue: events_unbound io_ring_exit_work
Call Trace:
 context_switch kernel/sched/core.c:4683 [inline]
 __schedule+0x934/0x2710 kernel/sched/core.c:5940
 schedule+0xd3/0x270 kernel/sched/core.c:6019
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6078
 __mutex_lock_common kernel/locking/mutex.c:1036 [inline]
 __mutex_lock+0x7b6/0x10a0 kernel/locking/mutex.c:1104
 io_sq_thread_park+0x79/0xd0 fs/io_uring.c:7361
 io_ring_exit_work+0x15a/0x15d0 fs/io_uring.c:8823
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
INFO: task iou-sqp-2939:2946 blocked for more than 143 seconds.
      Not tainted 5.13.0-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:iou-sqp-2939    state:D stack:28696 pid: 2946 ppid:  8489 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4683 [inline]
 __schedule+0x934/0x2710 kernel/sched/core.c:5940
 schedule+0xd3/0x270 kernel/sched/core.c:6019
 io_uring_cancel_generic+0x54d/0x890 fs/io_uring.c:9203
 io_sq_thread+0xa99/0x1250 fs/io_uring.c:6963
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Showing all locks held in the system:
1 lock held by khungtaskd/1643:
 #0: ffffffff8c17bb80 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6446
1 lock held by in:imklog/8150:
 #0: ffff888034297270 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:974
3 locks held by kworker/u4:4/9930:
 #0: ffff888011069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: ffff888011069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:620 [inline]
 #0: ffff888011069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
 #0: ffff888011069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:617 [inline]
 #0: ffff888011069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0: ffff888011069138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x871/0x1630 kernel/workqueue.c:2247
 #1: ffffc9000b31fdb0 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1630 kernel/workqueue.c:2251
 #2: ffff888045068870 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_park+0x79/0xd0 fs/io_uring.c:7361
1 lock held by iou-sqp-2939/2946:
 #0: ffff888045068870 (&sqd->lock){+.+.}-{3:3}, at: io_sqd_handle_event+0x2d6/0x350 fs/io_uring.c:6883

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

NMI backtrace for cpu 1
CPU: 1 PID: 1643 Comm: khungtaskd Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:96
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:209 [inline]
 watchdog+0xd4b/0xfb0 kernel/hung_task.c:294
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 9784 Comm: kworker/0:7 Not tainted 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_power_efficient gc_worker
RIP: 0010:check_region_inline mm/kasan/generic.c:175 [inline]
RIP: 0010:kasan_check_range+0x2a/0x180 mm/kasan/generic.c:189
Code: 48 85 f6 0f 84 70 01 00 00 49 89 f9 41 54 44 0f b6 c2 49 01 f1 55 53 0f 82 18 01 00 00 48 b8 ff ff ff ff ff 7f ff ff 48 39 c7 <0f> 86 05 01 00 00 49 83 e9 01 48 89 fd 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc9000aedfad8 EFLAGS: 00000016
RAX: ffff7fffffffffff RBX: 00000000000004c2 RCX: ffffffff815ac59f
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff9049d938
RBP: ffff88802d62267a R08: 0000000000000000 R09: ffffffff9049d940
R10: fffffbfff2093b27 R11: 0000000000000000 R12: ffff88802d622658
R13: ffff88802d621c40 R14: 0000000000000000 R15: 23147e44cee2677e
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb48abd5000 CR3: 000000000be8e000 CR4: 0000000000350ef0
Call Trace:
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
 hlock_class kernel/locking/lockdep.c:199 [inline]
 lookup_chain_cache_add kernel/locking/lockdep.c:3701 [inline]
 validate_chain kernel/locking/lockdep.c:3757 [inline]
 __lock_acquire+0x162f/0x54a0 kernel/locking/lockdep.c:5015
 lock_acquire kernel/locking/lockdep.c:5625 [inline]
 lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590
 process_one_work+0x8fc/0x1630 kernel/workqueue.c:2252
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-root 2021/07/11 03:04 upstream 3dbdb38e2869 8f5a7b8c .config log report syz INFO: task hung in io_sq_thread_park
ci-upstream-kasan-gce-root 2021/07/11 00:12 upstream 3dbdb38e2869 8f5a7b8c .config log report info INFO: task hung in io_sq_thread_park