Re: [syzbot] INFO: task hung in io_uring_cancel_generic

[Jens Axboe <axboe@kernel.dk>]

On 7/11/21 6:24 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    3dbdb38e Merge branch 'for-5.14' of git://git.kernel.org/p..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14cd9efbd00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a1fcf15a09815757
> dashboard link: https://syzkaller.appspot.com/bug?extid=ba6fcd859210f4e9e109
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13bbf280300000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1111ec9c300000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+ba6fcd859210f4e9e109@syzkaller.appspotmail.com
> 
> INFO: task syz-executor015:8439 blocked for more than 143 seconds.
>       Tainted: G        W         5.13.0-syzkaller #0
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> task:syz-executor015 state:D stack:28184 pid: 8439 ppid:  8438 flags:0x00000004
> 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_uring_files_cancel include/linux/io_uring.h:16 [inline]
>  do_exit+0x28b/0x2a50 kernel/exit.c:780
>  do_group_exit+0x125/0x310 kernel/exit.c:922
>  __do_sys_exit_group kernel/exit.c:933 [inline]
>  __se_sys_exit_group kernel/exit.c:931 [inline]
>  __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:931
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x43eac9
> RSP: 002b:00007ffc2d1b6378 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
> RAX: ffffffffffffffda RBX: 00000000004b02f0 RCX: 000000000043eac9
> RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
> RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 00000000f0ffffff
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004b02f0
> R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001
> INFO: lockdep is turned off.
> NMI backtrace for cpu 0
> CPU: 0 PID: 1650 Comm: khungtaskd Tainted: G        W         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 0 to CPUs 1:
> NMI backtrace for cpu 1 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:51 [inline]
> NMI backtrace for cpu 1 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
> NMI backtrace for cpu 1 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:109 [inline]
> NMI backtrace for cpu 1 skipped: idling at acpi_idle_do_entry+0x1c6/0x250 drivers/acpi/processor_idle.c:553

#syz test: git://git.kernel.dk/linux-block io_uring-5.14

-- 
Jens Axboe