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From: Pavel Begunkov <asml.silence@gmail.com>
To: syzbot <syzbot+b0c9d1588ae92866515f@syzkaller.appspotmail.com>,
	axboe@kernel.dk, io-uring@vger.kernel.org,
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] WARNING in io_try_cancel_userdata
Date: Mon, 23 Aug 2021 13:33:10 +0100	[thread overview]
Message-ID: <475c86fb-fe3c-7e68-b115-adf71cf63c27@gmail.com> (raw)
In-Reply-To: <c6ff4faf-bb08-d61a-8054-16b9010545eb@gmail.com>

On 8/23/21 12:36 PM, Pavel Begunkov wrote:
> 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@syzkaller.appspotmail.com
> 
> false positive, will delete the warning with explanation

There is a legit race though, a fix is sent.

> 
> 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@googlegroups.com.
>>
>> syzbot will keep track of this issue. See:
>> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>>
> 

-- 
Pavel Begunkov

  reply	other threads:[~2021-08-23 12:33 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23  9:17 [syzbot] WARNING in io_try_cancel_userdata syzbot
2021-08-23 11:36 ` Pavel Begunkov
2021-08-23 12:33   ` Pavel Begunkov [this message]
2021-08-23 22:14 ` syzbot

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