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Date: Sat, 1 May 2021 10:21:55 +0530
From: Palash Oswal <oswalpalash@...il.com>
To: Pavel Begunkov <asml.silence@...il.com>
Cc: Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
LKML <linux-kernel@...r.kernel.org>,
syzbot+11bf59db879676f59e52@...kaller.appspotmail.com
Subject: Re: INFO: task hung in io_uring_cancel_sqpoll
On Sat, May 1, 2021 at 2:35 AM Pavel Begunkov <asml.silence@...il.com> wrote:
>
> On 4/30/21 7:34 PM, Pavel Begunkov wrote:
> > On 4/30/21 4:02 PM, Palash Oswal wrote:
> >> On Fri, Apr 30, 2021 at 8:03 PM Pavel Begunkov <asml.silence@...il.com> wrote:
> >>>
> >>> On 4/30/21 3:21 PM, Palash Oswal wrote:
> >>>> On Thursday, March 18, 2021 at 9:40:21 PM UTC+5:30 syzbot wrote:
> >>>>>
> >>>>> Hello,
> >>>>>
> >>>>> syzbot found the following issue on:
> >>>>>
> >>>>> HEAD commit: 0d7588ab riscv: process: Fix no prototype for arch_dup_tas..
> >>>>> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes
> >>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=12dde5aed00000
> >>>>> kernel config: https://syzkaller.appspot.com/x/.config?x=81c0b708b31626cc
> >>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=11bf59db879676f59e52
> >>>>> userspace arch: riscv64
> >>>>> CC: [asml.s...@...il.com ax...@...nel.dk io-u...@...r.kernel.org linux-...@...r.kernel.org]
> >>>>>
> >>>>> Unfortunately, I don't have any reproducer for this issue yet.
> >>>
> >>> There was so many fixes in 5.12 after this revision, including sqpoll
> >>> cancellation related... Can you try something more up-to-date? Like
> >>> released 5.12 or for-next
> >>>
> >>
> >> The reproducer works for 5.12.
> >>
> >> I tested against the HEAD b1ef997bec4d5cf251bfb5e47f7b04afa49bcdfe
> >> commit on for-next tree
> >> https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/?h=for-next
> >> and the reproducer fails.
> >
> > Can't reproduce. Does it hang as in the original's report dmesg?
> > Can you paste logs?
>
> and `uname -r` if you could
root@...kaller:~# echo 30 > /proc/sys/kernel/hung_task_timeout_secs
root@...kaller:~# uname -a
Linux syzkaller 5.12.0 #112 SMP Sat May 1 10:13:41 IST 2021 x86_64 GNU/Linux
root@...kaller:~# ./repro
[ 70.412424] repro[365]: segfault at 0 ip 0000556d88201005 sp
00007ffc7ddf2cd0 error 6 in repro[556d8]
[ 70.417215] Code: cc 8b 75 c0 48 8b 45 e8 41 b9 00 00 00 00 41 89
d0 b9 11 80 00 00 ba 03 00 00 00 48
[ 121.593305] INFO: task iou-sqp-365:366 blocked for more than 30 seconds.
[ 121.594448] Not tainted 5.12.0 #112
[ 121.595072] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[ 121.596250] task:iou-sqp-365 state:D stack: 0 pid: 366
ppid: 364 flags:0x00004004
[ 121.597514] Call Trace:
[ 121.598019] __schedule+0xb1d/0x1130
[ 121.598774] ? __sched_text_start+0x8/0x8
[ 121.599580] ? io_wq_worker_sleeping+0x145/0x500
[ 121.600442] schedule+0x131/0x1c0
[ 121.600902] io_uring_cancel_sqpoll+0x288/0x350
[ 121.601571] ? io_sq_thread_unpark+0xd0/0xd0
[ 121.602410] ? mutex_lock+0xbb/0x130
[ 121.603027] ? init_wait_entry+0xe0/0xe0
[ 121.603573] ? wait_for_completion_killable_timeout+0x20/0x20
[ 121.604454] io_sq_thread+0x174c/0x18c0
[ 121.605014] ? io_rsrc_put_work+0x380/0x380
[ 121.605652] ? init_wait_entry+0xe0/0xe0
[ 121.606428] ? _raw_spin_lock_irq+0xa5/0x180
[ 121.607262] ? _raw_spin_lock_irqsave+0x190/0x190
[ 121.608005] ? calculate_sigpending+0x6b/0xa0
[ 121.608636] ? io_rsrc_put_work+0x380/0x380
[ 121.609301] ret_from_fork+0x22/0x30
root@...kaller:~# ps
PID TTY TIME CMD
294 ttyS0 00:00:00 login
357 ttyS0 00:00:00 bash
365 ttyS0 00:00:00 repro
370 ttyS0 00:00:00 ps
root@...kaller:~# kill -9 365
root@...kaller:~# [ 305.888970] INFO: task iou-sqp-365:366 blocked
for more than 215 seconds.
[ 305.893275] Not tainted 5.12.0 #112
[ 305.895507] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
[ 305.899685] task:iou-sqp-365 state:D stack: 0 pid: 366
ppid: 1 flags:0x00004004
[ 305.904071] Call Trace:
[ 305.905616] __schedule+0xb1d/0x1130
[ 305.907660] ? __sched_text_start+0x8/0x8
[ 305.910314] ? io_wq_worker_sleeping+0x145/0x500
[ 305.913328] schedule+0x131/0x1c0
[ 305.914562] io_uring_cancel_sqpoll+0x288/0x350
[ 305.916513] ? io_sq_thread_unpark+0xd0/0xd0
[ 305.918346] ? mutex_lock+0xbb/0x130
[ 305.919616] ? init_wait_entry+0xe0/0xe0
[ 305.920896] ? wait_for_completion_killable_timeout+0x20/0x20
[ 305.922805] io_sq_thread+0x174c/0x18c0
[ 305.923876] ? io_rsrc_put_work+0x380/0x380
[ 305.924748] ? init_wait_entry+0xe0/0xe0
[ 305.925523] ? _raw_spin_lock_irq+0xa5/0x180
[ 305.926353] ? _raw_spin_lock_irqsave+0x190/0x190
[ 305.927436] ? calculate_sigpending+0x6b/0xa0
[ 305.928266] ? io_rsrc_put_work+0x380/0x380
[ 305.929104] ret_from_fork+0x22/0x30
The trace from my syzkaller instance:
Syzkaller hit 'INFO: task hung in io_uring_cancel_sqpoll' bug.
syz-executor198[307]: segfault at 0 ip 00000000004020f3 sp
00007ffd21853620 error 6 in syz-executor198379463[401000+96000]
Code: 89 d8 8d 34 90 8b 45 04 ba 03 00 00 00 c1 e0 04 03 45 64 39 c6
48 0f 42 f0 45 31 c9 e8 96 8a 04 00 8b 75 00 41 89 d8 4c 89 ef <49> 89
06 41 b9 00 00 00 10 b9 11 80 00 00 ba 03 00 00 00 c1 e6 06
INFO: task iou-sqp-307:308 blocked for more than 120 seconds.
Not tainted 5.12.0 #2
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:iou-sqp-307 state:D stack: 0 pid: 308 ppid: 306 flags:0x00004004
Call Trace:
context_switch kernel/sched/core.c:4322 [inline]
__schedule+0x75f/0xa10 kernel/sched/core.c:5073
schedule+0xb7/0x110 kernel/sched/core.c:5152
io_uring_cancel_sqpoll+0x1c6/0x290 fs/io_uring.c:9018
io_sq_thread+0xf8c/0x1080 fs/io_uring.c:6836
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
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