Re: INFO: task hung in io_uring_cancel_generic

From: Hao Sun
Date: Wed Sep 08 2021 - 02:57:24 EST

Another similar report: INFO: task hung in io_ring_exit_work

INFO: task kworker/u9:3:1867 blocked for more than 143 seconds.
Not tainted 5.14.0+ #13
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u9:3 state:D stack:12344 pid: 1867 ppid: 2 flags:0x00004000
Workqueue: events_unbound io_ring_exit_work
Call Trace:
context_switch kernel/sched/core.c:4940 [inline]
__schedule+0x323/0xae0 kernel/sched/core.c:6287
schedule+0x36/0xe0 kernel/sched/core.c:6366
schedule_timeout+0x189/0x430 kernel/time/timer.c:1857
do_wait_for_common kernel/sched/completion.c:85 [inline]
__wait_for_common kernel/sched/completion.c:106 [inline]
wait_for_common kernel/sched/completion.c:117 [inline]
wait_for_completion+0xb4/0x110 kernel/sched/completion.c:138
io_ring_exit_work+0x287/0x850 fs/io_uring.c:9297
process_one_work+0x359/0x850 kernel/workqueue.c:2297
worker_thread+0x41/0x4d0 kernel/workqueue.c:2444
kthread+0x178/0x1b0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
INFO: task kworker/u9:4:2050 blocked for more than 143 seconds.
Not tainted 5.14.0+ #13
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u9:4 state:D stack:12232 pid: 2050 ppid: 2 flags:0x00004000
Workqueue: events_unbound io_ring_exit_work
Call Trace:
context_switch kernel/sched/core.c:4940 [inline]
__schedule+0x323/0xae0 kernel/sched/core.c:6287
schedule+0x36/0xe0 kernel/sched/core.c:6366
schedule_timeout+0x189/0x430 kernel/time/timer.c:1857
do_wait_for_common kernel/sched/completion.c:85 [inline]
__wait_for_common kernel/sched/completion.c:106 [inline]
wait_for_common kernel/sched/completion.c:117 [inline]
wait_for_completion+0xb4/0x110 kernel/sched/completion.c:138
io_ring_exit_work+0x287/0x850 fs/io_uring.c:9297
process_one_work+0x359/0x850 kernel/workqueue.c:2297
worker_thread+0x41/0x4d0 kernel/workqueue.c:2444
kthread+0x178/0x1b0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Showing all locks held in the system:
1 lock held by khungtaskd/1340:
#0: ffffffff85a1d3a0 (rcu_read_lock){....}-{1:2}, at:
debug_show_all_locks+0xe/0x1a0 kernel/locking/lockdep.c:6446
2 locks held by kworker/u9:3/1867:
#0: ffff888008c5c938 ((wq_completion)events_unbound){+.+.}-{0:0}, at:
set_work_data kernel/workqueue.c:633 [inline]
#0: ffff888008c5c938 ((wq_completion)events_unbound){+.+.}-{0:0}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
#0: ffff888008c5c938 ((wq_completion)events_unbound){+.+.}-{0:0}, at:
process_one_work+0x2a0/0x850 kernel/workqueue.c:2268
#1: ffffc90003e67e70
((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: set_work_data
kernel/workqueue.c:633 [inline]
#1: ffffc90003e67e70
((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
#1: ffffc90003e67e70
((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at:
process_one_work+0x2a0/0x850 kernel/workqueue.c:2268
2 locks held by kworker/u9:4/2050:
#0: ffff888008c5c938 ((wq_completion)events_unbound){+.+.}-{0:0}, at:
set_work_data kernel/workqueue.c:633 [inline]
#0: ffff888008c5c938 ((wq_completion)events_unbound){+.+.}-{0:0}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
#0: ffff888008c5c938 ((wq_completion)events_unbound){+.+.}-{0:0}, at:
process_one_work+0x2a0/0x850 kernel/workqueue.c:2268
#1: ffffc90004327e70
((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: set_work_data
kernel/workqueue.c:633 [inline]
#1: ffffc90004327e70
((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:661 [inline]
#1: ffffc90004327e70
((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at:
process_one_work+0x2a0/0x850 kernel/workqueue.c:2268
1 lock held by in:imklog/8089:
#0: ffff88800ece7ef0 (&f->f_pos_lock){+.+.}-{3:3}, at:
__fdget_pos+0x55/0x60 fs/file.c:990

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

NMI backtrace for cpu 0
CPU: 0 PID: 1340 Comm: khungtaskd Not tainted 5.14.0+ #13
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x8d/0xcf lib/dump_stack.c:105
nmi_cpu_backtrace+0x1e9/0x210 lib/nmi_backtrace.c:105
nmi_trigger_cpumask_backtrace+0x120/0x180 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline]
watchdog+0x4e1/0x980 kernel/hung_task.c:295
kthread+0x178/0x1b0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Sending NMI from CPU 0 to CPUs 1-3:
NMI backtrace for cpu 1
CPU: 1 PID: 4934 Comm: systemd-journal Not tainted 5.14.0+ #13
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:lockdep_enabled kernel/locking/lockdep.c:91 [inline]
RIP: 0010:lock_acquire+0x1a4/0x340 kernel/locking/lockdep.c:5601
Code: 04 25 28 00 00 00 0f 85 b5 01 00 00 48 83 c4 38 5b 5d 41 5c 41
5d 41 5e 41 5f c3 65 48 8b 04 25 40 70 01 00 8b 80 f4 09 00 00 <85> c0
0f 85 c5 fe ff ff 9c 8f 04 24 fa 48 c7 c7 a0 36 5d 85 e8 e3
RSP: 0018:ffffc9000086fe18 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffffffff852a8b94 RDI: ffffffff853cae8e
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff85a1d3a0
R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f940a97b8c0(0000) GS:ffff88813dc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9407aa3000 CR3: 000000000f49a000 CR4: 0000000000750ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
rcu_lock_acquire include/linux/rcupdate.h:267 [inline]
rcu_read_lock include/linux/rcupdate.h:687 [inline]
dput+0x72/0x650 fs/dcache.c:874
path_put+0x12/0x20 fs/namei.c:557
do_faccessat+0x1fa/0x370 fs/open.c:455
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f9409c379c7
Code: 83 c4 08 48 3d 01 f0 ff ff 73 01 c3 48 8b 0d c8 d4 2b 00 f7 d8
64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 b8 15 00 00 00 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 8b 0d a1 d4 2b 00 f7 d8 64 89 01 48
RSP: 002b:00007ffeead2d338 EFLAGS: 00000246 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 00007ffeead30250 RCX: 00007f9409c379c7
RDX: 00007f940a6a8a00 RSI: 0000000000000000 RDI: 000055d9e89aa9a3
RBP: 00007ffeead2d370 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000069 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007ffeead30250 R15: 00007ffeead2d860
NMI backtrace for cpu 2 skipped: idling at native_safe_halt
arch/x86/include/asm/irqflags.h:51 [inline]
NMI backtrace for cpu 2 skipped: idling at arch_safe_halt
arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 2 skipped: idling at default_idle+0xb/0x10
arch/x86/kernel/process.c:716
NMI backtrace for cpu 3
CPU: 3 PID: 8091 Comm: rs:main Q:Reg Not tainted 5.14.0+ #13
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:memset_erms+0x9/0x10 arch/x86/lib/memset_64.S:64
Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6
f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa
4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01
RSP: 0018:ffffc90007a23ba8 EFLAGS: 00010216
RAX: 0000000000000000 RBX: ffff88810cd3ec78 RCX: 0000000000000c85
RDX: 0000000000000d05 RSI: 0000000000000000 RDI: ffff888107f7b37b
RBP: 0000000000001000 R08: 0000000000000000 R09: ffff888107f7b2fb
R10: ffffc90007a23978 R11: 0000000000000005 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000001000 R15: ffffea00041fdec0
FS: 00007fd86dba4700(0000) GS:ffff88813dd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d6e0599858 CR3: 0000000012b38000 CR4: 0000000000750ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
memset include/linux/fortify-string.h:175 [inline]
zero_user_segments include/linux/highmem.h:211 [inline]
ext4_block_write_begin+0x63e/0x980 fs/ext4/inode.c:1089
ext4_da_write_begin+0x275/0x610 fs/ext4/inode.c:3021
generic_perform_write+0xce/0x220 mm/filemap.c:3770
ext4_buffered_write_iter+0xd6/0x190 fs/ext4/file.c:269
ext4_file_write_iter+0x80/0x940 fs/ext4/file.c:680
call_write_iter include/linux/fs.h:2163 [inline]
new_sync_write+0x18d/0x260 fs/read_write.c:507
vfs_write+0x43b/0x4a0 fs/read_write.c:594
ksys_write+0xd2/0x120 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x34/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd8705e81cd
Code: c2 20 00 00 75 10 b8 01 00 00 00 0f 05 48 3d 01 f0 ff ff 73 31
c3 48 83 ec 08 e8 ae fc ff ff 48 89 04 24 b8 01 00 00 00 0f 05 <48> 8b
3c 24 48 89 c2 e8 f7 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fd86dba3590 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd8640268f0 RCX: 00007fd8705e81cd
RDX: 00000000000004ce RSI: 00007fd8640268f0 RDI: 0000000000000008
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000293 R12: 00007fd864026670
R13: 00007fd86dba35b0 R14: 00005563e5cf4440 R15: 00000000000004ce
----------------
Code disassembly (best guess):
0: 04 25 add $0x25,%al
2: 28 00 sub %al,(%rax)
4: 00 00 add %al,(%rax)
6: 0f 85 b5 01 00 00 jne 0x1c1
c: 48 83 c4 38 add $0x38,%rsp
10: 5b pop %rbx
11: 5d pop %rbp
12: 41 5c pop %r12
14: 41 5d pop %r13
16: 41 5e pop %r14
18: 41 5f pop %r15
1a: c3 retq
1b: 65 48 8b 04 25 40 70 mov %gs:0x17040,%rax
22: 01 00
24: 8b 80 f4 09 00 00 mov 0x9f4(%rax),%eax
* 2a: 85 c0 test %eax,%eax <-- trapping instruction
2c: 0f 85 c5 fe ff ff jne 0xfffffef7
32: 9c pushfq
33: 8f 04 24 popq (%rsp)
36: fa cli
37: 48 c7 c7 a0 36 5d 85 mov $0xffffffff855d36a0,%rdi
3e: e8 .byte 0xe8
3f: e3 .byte 0xe3%

Hao Sun <sunhao.th@xxxxxxxxx> 于2021年9月8日周三 上午9:01写道：
>
> Pavel Begunkov <asml.silence@xxxxxxxxx> 于2021年9月8日周三 上午5:31写道：
> >
> > On 9/7/21 8:30 PM, Jens Axboe wrote:
> > > On 9/7/21 5:50 AM, Hao Sun wrote:
> > >> Hello,
> > >>
> > >> When using Healer to fuzz the latest Linux kernel, the following crash
> > >> was triggered.
> > >>
> > >> HEAD commit: 7d2a07b76933 Linux 5.14
> > >> git tree: upstream
> > >> console output:
> > >> https://drive.google.com/file/d/1c8uRooM0TwJiTIwEviOCB4RC-hhOgGHR/view?usp=sharing
> > >> kernel config: https://drive.google.com/file/d/1XD9WYDViQLSXN7RGwH8AGGDvP9JvOghx/view?usp=sharing
> > >> Similar report:
> > >> https://groups.google.com/u/1/g/syzkaller-bugs/c/FvdcTiJIGtY/m/PcXkoenUAAAJ
> > >>
> > >> Sorry, I don't have a reproducer for this crash, hope the symbolized
> > >> report can help.
> > >> If you fix this issue, please add the following tag to the commit:
> > >> Reported-by: Hao Sun <sunhao.th@xxxxxxxxx>
> > >
> > > Would be great with a reproducer for this one, though...
> >
> > And syzbot usually sends an execution log with all syz programs
> > it run, which may be helpful. Any chance you have anything similar
> > left?
> >
>
> Yes, found it[1]. Here is an execution history with latest 1024
> executed progs before crash saved.
> Hope it can help. I'll also follow this crash closely, see if Healer
> can find a reproducer and send it to you once it found.
>
> [1] https://drive.google.com/file/d/14k8qOFeyKPD4HsqOpIjud3b9jsxFSo-u/view?usp=sharing
>
> > --
> > Pavel Begunkov