linux-kernel - [syzbot] WARNING in io_poll_task

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Message-ID: <0000000000007a0d5705cfea99b2@google.com>
Date:   Wed, 03 Nov 2021 16:16:27 -0700
From:   syzbot <syzbot+804709f40ea66018e544@...kaller.appspotmail.com>
To:     asml.silence@...il.com, axboe@...nel.dk, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        xiaoguang.wang@...ux.alibaba.com
Subject: [syzbot] WARNING in io_poll_task_func (2)

Hello,

syzbot found the following issue on:

HEAD commit:    bdcc9f6a5682 Add linux-next specific files for 20211029
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14ab0e5cb00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4b504bcb4c507265
dashboard link: https://syzkaller.appspot.com/bug?extid=804709f40ea66018e544
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15710012b00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11862ef4b00000

The issue was bisected to:

commit 34ced75ca1f63fac6148497971212583aa0f7a87
Author: Xiaoguang Wang <xiaoguang.wang@...ux.alibaba.com>
Date:   Mon Oct 25 05:38:48 2021 +0000

    io_uring: reduce frequent add_wait_queue() overhead for multi-shot poll request

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13c264bcb00000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=102264bcb00000
console output: https://syzkaller.appspot.com/x/log.txt?x=17c264bcb00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+804709f40ea66018e544@...kaller.appspotmail.com
Fixes: 34ced75ca1f6 ("io_uring: reduce frequent add_wait_queue() overhead for multi-shot poll request")

------------[ cut here ]------------
WARNING: CPU: 1 PID: 9467 at fs/io_uring.c:1183 req_ref_put_and_test fs/io_uring.c:1183 [inline]
WARNING: CPU: 1 PID: 9467 at fs/io_uring.c:1183 req_ref_put_and_test fs/io_uring.c:1178 [inline]
WARNING: CPU: 1 PID: 9467 at fs/io_uring.c:1183 io_put_req_find_next fs/io_uring.c:2392 [inline]
WARNING: CPU: 1 PID: 9467 at fs/io_uring.c:1183 io_poll_task_func+0x81d/0x9f0 fs/io_uring.c:5412
Modules linked in:
CPU: 1 PID: 9467 Comm: syz-executor199 Not tainted 5.15.0-rc7-next-20211029-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:1183 [inline]
RIP: 0010:req_ref_put_and_test fs/io_uring.c:1178 [inline]
RIP: 0010:io_put_req_find_next fs/io_uring.c:2392 [inline]
RIP: 0010:io_poll_task_func+0x81d/0x9f0 fs/io_uring.c:5412
Code: e8 e8 f3 da ff f0 ff 8d 80 00 00 00 0f 94 c3 31 ff 89 de e8 15 33 94 ff 84 db 0f 84 47 f8 ff ff e9 a4 fa ff ff e8 23 2f 94 ff <0f> 0b eb c5 e8 4a f0 da ff e9 0e f8 ff ff 4c 89 f7 e8 0d f0 da ff
RSP: 0018:ffffc9000daa7d98 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 000000000000007f RCX: 0000000000000000
RDX: ffff88806d821d40 RSI: ffffffff81e39d0d RDI: 0000000000000003
RBP: ffff888072c1b140 R08: 000000000000007f R09: ffff888072c1b1c3
R10: ffffffff81e39cd1 R11: 0000000000000000 R12: ffff888072c1b1c0
R13: ffff88806b2a0000 R14: 0000000000000016 R15: ffff8880173f03c0
FS:  00007f1c4f07e700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001348 CR3: 000000001d66d000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tctx_task_work+0x1b3/0x630 fs/io_uring.c:2207
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 tracehook_notify_signal include/linux/tracehook.h:214 [inline]
 handle_signal_work kernel/entry/common.c:146 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
 exit_to_user_mode_prepare+0x256/0x290 kernel/entry/common.c:207
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f1c4f0d57f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 a1 18 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1c4f07e2f8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: 000000000000052c RBX: 00007f1c4f1574a8 RCX: 00007f1c4f0d57f9
RDX: 0000000000000000 RSI: 000000000000450e RDI: 0000000000000006
RBP: 00007f1c4f1574a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f1c4f124598
R13: 0000000000000006 R14: 00007f1c4f07e400 R15: 0000000000022000
 </TASK>


---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
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