linux-kernel - Re: [syzbot] WARNING in io_try_cancel

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Message-ID: <c6ff4faf-bb08-d61a-8054-16b9010545eb@gmail.com>
Date:   Mon, 23 Aug 2021 12:36:06 +0100
From:   Pavel Begunkov <asml.silence@...il.com>
To:     syzbot <syzbot+b0c9d1588ae92866515f@...kaller.appspotmail.com>,
        axboe@...nel.dk, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] WARNING in io_try_cancel_userdata

On 8/23/21 10:17 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    86ed57fd8c93 Add linux-next specific files for 20210820
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1565bd55300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f64eccb415bd479d
> dashboard link: https://syzkaller.appspot.com/bug?extid=b0c9d1588ae92866515f
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
> 
> 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+b0c9d1588ae92866515f@...kaller.appspotmail.com

false positive, will delete the warning with explanation

p.s. easily reproducible, we'll add a test covering cancel from io-wq 

> 
> WARNING: CPU: 1 PID: 5870 at fs/io_uring.c:5975 io_try_cancel_userdata+0x30f/0x540 fs/io_uring.c:5975
> Modules linked in:
> CPU: 0 PID: 5870 Comm: iou-wrk-5860 Not tainted 5.14.0-rc6-next-20210820-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:io_try_cancel_userdata+0x30f/0x540 fs/io_uring.c:5975
> Code: 07 e8 e5 9d 95 ff 48 8b 7c 24 08 e8 ab 02 58 07 e9 6f fe ff ff e8 d1 9d 95 ff 41 bf 8e ff ff ff e9 5f fe ff ff e8 c1 9d 95 ff <0f> 0b 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 80 3c 02
> RSP: 0018:ffffc900055f7a88 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffff888181aa83c0 RCX: 0000000000000000
> RDX: ffff88803fb88000 RSI: ffffffff81e0dacf RDI: ffff888181aa8410
> RBP: ffff88803fb88000 R08: ffffffff899ad660 R09: ffffffff81e23c44
> R10: 0000000000000027 R11: 000000000000000e R12: 1ffff92000abef53
> R13: 0000000000000000 R14: ffff8880b34d0000 R15: ffff888181aa8420
> FS:  00007f7a08d50700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000001b2c72e000 CR3: 0000000168b9b000 CR4: 00000000001506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
> Call Trace:
>  io_async_cancel fs/io_uring.c:6014 [inline]
>  io_issue_sqe+0x22d5/0x65a0 fs/io_uring.c:6407
>  io_wq_submit_work+0x1dc/0x300 fs/io_uring.c:6511
>  io_worker_handle_work+0xa45/0x1840 fs/io-wq.c:533
>  io_wqe_worker+0x2cc/0xbb0 fs/io-wq.c:582
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 

-- 
Pavel Begunkov