Re: WARNING in io_wq_submit_work

[Pavel Begunkov <asml.silence@gmail.com>]

On 17/01/2021 08:27, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    0da0a8a0 Merge tag 'scsi-fixes' of git://git.kernel.org/pu..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=12f2309f500000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=ee2266946ed36986
> dashboard link: https://syzkaller.appspot.com/bug?extid=f655445043a26a7cfab8
> compiler:       clang version 11.0.1
> 
> 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+f655445043a26a7cfab8@syzkaller.appspotmail.com

#syz fix: io_uring: cancel all requests on task exit

the patch makes io_uring_cancel_files() effectively unreachable.

> 
> ------------[ cut here ]------------
> do not call blocking ops when !TASK_RUNNING; state=2 set at [<00000000ced9dbfc>] prepare_to_wait+0x1f4/0x3b0 kernel/sched/wait.c:262
> WARNING: CPU: 1 PID: 19888 at kernel/sched/core.c:7853 __might_sleep+0xed/0x100 kernel/sched/core.c:7848
> Modules linked in:
> CPU: 0 PID: 19888 Comm: syz-executor.3 Not tainted 5.11.0-rc3-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:__might_sleep+0xed/0x100 kernel/sched/core.c:7848
> Code: fc ff df 41 80 3c 06 00 74 08 48 89 ef e8 cb 2e 6c 00 48 8b 4d 00 48 c7 c7 c0 d4 0d 8a 48 89 de 48 89 ca 31 c0 e8 23 5e f3 ff <0f> 0b eb 8e 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 89
> RSP: 0018:ffffc900089df3c0 EFLAGS: 00010246
> RAX: 24183d53a1679b00 RBX: 0000000000000002 RCX: ffff888013853780
> RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
> RBP: ffff888013854d98 R08: ffffffff8163c792 R09: ffffed10173a60b8
> R10: ffffed10173a60b8 R11: 0000000000000000 R12: ffffffff8a0e5f60
> R13: ffff888013853798 R14: 1ffff1100270a9b3 R15: 00000000000003a7
> FS:  00007fe439981700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000016b538d CR3: 0000000026e00000 CR4: 00000000001506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
> Call Trace:
>  __mutex_lock_common+0xc4/0x2ef0 kernel/locking/mutex.c:935
>  __mutex_lock kernel/locking/mutex.c:1103 [inline]
>  mutex_lock_nested+0x1a/0x20 kernel/locking/mutex.c:1118
>  io_wq_submit_work+0x39a/0x720 fs/io_uring.c:6411
>  io_run_cancel fs/io-wq.c:856 [inline]
>  io_wqe_cancel_pending_work fs/io-wq.c:990 [inline]
>  io_wq_cancel_cb+0x614/0xcb0 fs/io-wq.c:1027
>  io_uring_cancel_files fs/io_uring.c:8874 [inline]
>  io_uring_cancel_task_requests fs/io_uring.c:8952 [inline]
>  __io_uring_files_cancel+0x115d/0x19e0 fs/io_uring.c:9038
>  io_uring_files_cancel include/linux/io_uring.h:51 [inline]
>  do_exit+0x2e6/0x2490 kernel/exit.c:780
>  do_group_exit+0x168/0x2d0 kernel/exit.c:922
>  get_signal+0x16b5/0x2030 kernel/signal.c:2770
>  arch_do_signal_or_restart+0x8e/0x6a0 arch/x86/kernel/signal.c:811
>  handle_signal_work kernel/entry/common.c:147 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
>  exit_to_user_mode_prepare+0xac/0x1e0 kernel/entry/common.c:201
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
>  syscall_exit_to_user_mode+0x48/0x190 kernel/entry/common.c:302
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x45e219
> Code: 0d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007fe439980cf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
> RAX: fffffffffffffe00 RBX: 000000000119bf88 RCX: 000000000045e219
> RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000119bf88
> RBP: 000000000119bf80 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000119bf8c
> R13: 00007ffe7c5112ff R14: 00007fe4399819c0 R15: 000000000119bf8c
> 
> 
> ---
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-- 
Pavel Begunkov