Re: [syzbot] WARNING in io_link_timeout_fn

[Pavel Begunkov]

On 5/12/21 11:38 PM, syzbot wrote:
> Hello,
> 
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> WARNING in io_req_complete_failed

Let's get more info on it

#syz test: https://github.com/isilence/linux.git syz_test6

> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 10153 at fs/io_uring.c:1505 req_ref_put_and_test fs/io_uring.c:1505 [inline]
> WARNING: CPU: 0 PID: 10153 at fs/io_uring.c:1505 io_put_req fs/io_uring.c:2171 [inline]
> WARNING: CPU: 0 PID: 10153 at fs/io_uring.c:1505 io_req_complete_failed+0x2ee/0x5a0 fs/io_uring.c:1649
> Modules linked in:
> CPU: 1 PID: 10153 Comm: syz-executor.3 Not tainted 5.12.0-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:req_ref_put_and_test fs/io_uring.c:1505 [inline]
> RIP: 0010:io_put_req fs/io_uring.c:2171 [inline]
> RIP: 0010:io_req_complete_failed+0x2ee/0x5a0 fs/io_uring.c:1649
> Code: 58 bd da ff be 01 00 00 00 4c 89 f7 e8 5b 78 fe ff e9 09 fe ff ff e8 f1 32 97 ff 4c 89 ef e8 a9 fd 65 ff eb cb e8 e2 32 97 ff <0f> 0b e9 c8 fd ff ff 4c 89 f7 e8 23 0b db ff e9 3c fd ff ff 4c 89
> RSP: 0018:ffffc9000afbfd10 EFLAGS: 00010293
> 
> RAX: 0000000000000000 RBX: 000000000000007f RCX: 0000000000000000
> RDX: ffff88801f5e0000 RSI: ffffffff81dd35ae RDI: 0000000000000003
> RBP: ffff888043314dc0 R08: 000000000000007f R09: ffff888043314e1f
> R10: ffffffff81dd3374 R11: 000000000000000f R12: ffffffffffffffea
> R13: ffff888043314e1c R14: ffff888043314e18 R15: 00000000ffffffea
> FS:  00007fac1b577700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f04f797dd40 CR3: 0000000012dfb000 CR4: 00000000001506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  __io_queue_sqe+0x61e/0x10f0 fs/io_uring.c:6440
>  __io_req_task_submit+0x103/0x120 fs/io_uring.c:2037
>  __tctx_task_work fs/io_uring.c:1908 [inline]
>  tctx_task_work+0x24e/0x550 fs/io_uring.c:1922
>  task_work_run+0xdd/0x1a0 kernel/task_work.c:161
>  tracehook_notify_signal include/linux/tracehook.h:212 [inline]
>  handle_signal_work kernel/entry/common.c:145 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
>  exit_to_user_mode_prepare+0x24a/0x280 kernel/entry/common.c:208
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
>  syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
>  do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:57
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x4665f9
> Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> 
> 
> Tested on:
> 
> commit:         a298232e io_uring: fix link timeout refs
> git tree:       git://git.kernel.dk/linux-block.git io_uring-5.13
> console output: https://syzkaller.appspot.com/x/log.txt?x=15f82965d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=ae2e6c63d6410fd3
> dashboard link: https://syzkaller.appspot.com/bug?extid=5a864149dd970b546223
> compiler:       
> 

-- 
Pavel Begunkov