[syzbot] [io-uring?] WARNING in io_cqring_event_overflow (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 74564adfd352 Add linux-next specific files for 20240701
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=135c21d1980000
kernel config: https://syzkaller.appspot.com/x/.config?x=111e4e0e6fbde8f0
dashboard link: https://syzkaller.appspot.com/bug?extid=f7f9c893345c5c615d34
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/04b8d7db78fb/disk-74564adf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d996f4370003/vmlinux-74564adf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6e7e630054e7/bzImage-74564adf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f7f9c8...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 5145 at io_uring/io_uring.c:703 io_cqring_event_overflow+0x442/0x660 io_uring/io_uring.c:703
Modules linked in:
CPU: 0 UID: 0 PID: 5145 Comm: kworker/0:4 Not tainted 6.10.0-rc6-next-20240701-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Workqueue: events io_fallback_req_func
RIP: 0010:io_cqring_event_overflow+0x442/0x660 io_uring/io_uring.c:703
Code: 0f 95 c0 48 83 c4 20 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc e8 ed ae ed fc 90 0f 0b 90 e9 c5 fc ff ff e8 df ae ed fc 90 <0f> 0b 90 e9 6e fc ff ff e8 d1 ae ed fc c6 05 f6 ea f3 0a 01 90 48
RSP: 0018:ffffc900040d7a08 EFLAGS: 00010293
RAX: ffffffff84a5cf11 RBX: 0000000000000000 RCX: ffff8880299bbc00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff84a5cb74 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff84a9f5d0 R12: ffff888021d0a000
R13: 0000000000000000 R14: ffff888021d0a000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f4e669ff800 CR3: 000000002a360000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__io_post_aux_cqe io_uring/io_uring.c:816 [inline]
io_add_aux_cqe+0x27c/0x320 io_uring/io_uring.c:837
io_msg_tw_complete+0x9d/0x4d0 io_uring/msg_ring.c:78
io_fallback_req_func+0xce/0x1c0 io_uring/io_uring.c:256
process_one_work kernel/workqueue.c:3224 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3305
worker_thread+0x86d/0xd40 kernel/workqueue.c:3383
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:144
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>


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[Pavel Begunkov]

On 7/1/24 21:50, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 74564adfd352 Add linux-next specific files for 20240701
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=135c21d1980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=111e4e0e6fbde8f0
> dashboard link: https://syzkaller.appspot.com/bug?extid=f7f9c893345c5c615d34
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/04b8d7db78fb/disk-74564adf.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/d996f4370003/vmlinux-74564adf.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/6e7e630054e7/bzImage-74564adf.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+f7f9c8...@syzkaller.appspotmail.com
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 5145 at io_uring/io_uring.c:703 io_cqring_event_overflow+0x442/0x660 io_uring/io_uring.c:703

Makes sense, it needs locking around overflowing, will fix it

--
Pavel Begunkov