[syzbot] INFO: task hung in io_uring_cancel_generic (2)

syzbot
2021-11-17T21:03:38Z

Hello,

syzbot found the following issue on:

HEAD commit: 8ab774587903 Merge tag 'trace-v5.16-5' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12b2344eb00000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d3b8fd1977c1e73
dashboard link: https://syzkaller.appspot.com/bug?extid=21e6887c0be14181206d
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+21e6887c0be14181206d@syzkaller.appspotmail.com

INFO: task syz-executor.1:1474 blocked for more than 143 seconds.
Not tainted 5.16.0-rc1-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.1 state:D stack:26328 pid: 1474 ppid: 6663 flags:0x00024004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:4972 [inline]
__schedule+0xa9a/0x4940 kernel/sched/core.c:6253
schedule+0xd2/0x260 kernel/sched/core.c:6326
io_uring_cancel_generic+0x53d/0x690 fs/io_uring.c:9846
io_uring_files_cancel include/linux/io_uring.h:16 [inline]
do_exit+0x60c/0x2b40 kernel/exit.c:787
do_group_exit+0x125/0x310 kernel/exit.c:929
get_signal+0x47d/0x2220 kernel/signal.c:2830
arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868
handle_signal_work kernel/entry/common.c:148 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207
__syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd09b5fbae9
RSP: 002b:00007fd098b71218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fd09b70ef68 RCX: 00007fd09b5fbae9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fd09b70ef68
RBP: 00007fd09b70ef60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd09b70ef6c
R13: 00007fd09bc42b2f R14: 00007fd098b71300 R15: 0000000000022000
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8bb83a60 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6458
1 lock held by in:imklog/6233:
#0: ffff8880208d7270 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:990
2 locks held by kworker/u4:7/9581:

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 5.16.0-rc1-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
nmi_cpu_backtrace.cold+0x47/0x144 lib/nmi_backtrace.c:105
nmi_trigger_cpumask_backtrace+0x1ae/0x220 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+0xc1d/0xf50 kernel/hung_task.c:295
kthread+0x405/0x4f0 kernel/kthread.c:327
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 2969 Comm: systemd-journal Not tainted 5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__lock_acquire+0x8fe/0x54a0 kernel/locking/lockdep.c:5000
Code: 03 38 d0 7c 08 84 d2 0f 85 d7 48 00 00 8b 0d a9 a5 ef 0e 85 c9 0f 84 05 07 00 00 49 8d 85 50 0a 00 00 48 89 c2 48 89 44 24 68 <48> b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 73 37
RSP: 0018:ffffc900020bfa38 EFLAGS: 00000047
RAX: ffff88807ad2c450 RBX: 0000000000000000 RCX: ffffffff815cab4a
RDX: ffff88807ad2c450 RSI: 0000000000000008 RDI: ffffffff8ff76a00
RBP: ffff88807ad2c482 R08: 0000000000000000 R09: ffffffff8ff76a07
R10: fffffbfff1feed40 R11: 0000000000000000 R12: ffff88807ad2c460
R13: ffff88807ad2ba00 R14: 0000000000000000 R15: 0000000000000002
FS: 00007f19aca9d8c0(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f19a99a0028 CR3: 000000001cdbc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
lock_acquire kernel/locking/lockdep.c:5637 [inline]
lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5602
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
__debug_object_init+0xb1/0xd10 lib/debugobjects.c:569
debug_object_init lib/debugobjects.c:620 [inline]
debug_object_activate+0x32c/0x3e0 lib/debugobjects.c:706
debug_rcu_head_queue kernel/rcu/rcu.h:176 [inline]
__call_rcu kernel/rcu/tree.c:2969 [inline]
call_rcu+0x2c/0x740 kernel/rcu/tree.c:3065
task_work_run+0xdd/0x1a0 kernel/task_work.c:164
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:207
__syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f19ac02c840
Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24
RSP: 002b:00007fffa9120ee8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: fffffffffffffffe RBX: 00007fffa91211f0 RCX: 00007f19ac02c840
RDX: 00000000000001a0 RSI: 0000000000080042 RDI: 00005590b7443010
RBP: 000000000000000d R08: 0000000000000000 R09: 00000000ffffffff
R10: 0000000000000069 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00005590b7436040 R14: 00007fffa91211b0 R15: 00005590b7442e30
</TASK>
----------------
Code disassembly (best guess):
0: 03 38 add (%rax),%edi
2: d0 7c 08 84 sarb -0x7c(%rax,%rcx,1)
6: d2 0f rorb %cl,(%rdi)
8: 85 d7 test %edx,%edi
a: 48 00 00 rex.W add %al,(%rax)
d: 8b 0d a9 a5 ef 0e mov 0xeefa5a9(%rip),%ecx # 0xeefa5bc
13: 85 c9 test %ecx,%ecx
15: 0f 84 05 07 00 00 je 0x720
1b: 49 8d 85 50 0a 00 00 lea 0xa50(%r13),%rax
22: 48 89 c2 mov %rax,%rdx
25: 48 89 44 24 68 mov %rax,0x68(%rsp)
* 2a: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax <-- trapping instruction
31: fc ff df
34: 48 c1 ea 03 shr $0x3,%rdx
38: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
3c: 0f .byte 0xf
3d: 85 73 37 test %esi,0x37(%rbx)

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