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* [syzbot] WARNING in __percpu_ref_exit (2)
@ 2021-03-15 11:58 syzbot
  2021-03-15 12:18 ` Pavel Begunkov
                   ` (3 more replies)
  0 siblings, 4 replies; 11+ messages in thread
From: syzbot @ 2021-03-15 11:58 UTC (permalink / raw)
  To: asml.silence, axboe, io-uring, linux-kernel, syzkaller-bugs

Hello,

syzbot found the following issue on:

HEAD commit:    75013c6c Merge tag 'perf_urgent_for_v5.12-rc3' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=174df32ad00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=844457676c06b88c
dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
userspace arch: i386

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+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 53 at lib/percpu-refcount.c:113 __percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113
Modules linked in:
CPU: 1 PID: 53 Comm: kworker/u4:2 Not tainted 5.12.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound io_ring_exit_work
RIP: 0010:__percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113
Code: fd 49 8d 7c 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 61 49 83 7c 24 10 00 74 07 e8 28 42 ac fd <0f> 0b e8 21 42 ac fd 48 89 ef e8 e9 fa da fd 48 89 da 48 b8 00 00
RSP: 0018:ffffc90000f1fb78 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88805c976000 RCX: 0000000000000000
RDX: ffff888011839bc0 RSI: ffffffff83c76be8 RDI: ffff88802b2a9010
RBP: 0000607f46077778 R08: 0000000000000000 R09: ffffffff8fab0967
R10: ffffffff83c76b88 R11: 0000000000000009 R12: ffff88802b2a9000
R13: 0000000000000001 R14: ffff88802b2a9000 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000085a0004 CR3: 000000001896a000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 percpu_ref_exit+0x3b/0x140 lib/percpu-refcount.c:134
 io_ring_ctx_free fs/io_uring.c:8419 [inline]
 io_ring_exit_work+0x599/0xcf0 fs/io_uring.c:8565
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294


---
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.

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
  2021-03-15 11:58 [syzbot] WARNING in __percpu_ref_exit (2) syzbot
@ 2021-03-15 12:18 ` Pavel Begunkov
       [not found] ` <20210318083340.1900-1-hdanton@sina.com>
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 11+ messages in thread
From: Pavel Begunkov @ 2021-03-15 12:18 UTC (permalink / raw)
  To: syzbot, axboe, io-uring, linux-kernel, syzkaller-bugs

On 15/03/2021 11:58, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    75013c6c Merge tag 'perf_urgent_for_v5.12-rc3' of git://gi..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=174df32ad00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=844457676c06b88c
> dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
> userspace arch: i386
> 
> 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+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 53 at lib/percpu-refcount.c:113 __percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113

if (percpu_count) {
	/* non-NULL confirm_switch indicates switching in progress */
	WARN_ON_ONCE(ref->data && ref->data->confirm_switch);
	...
}

Points to this warning. Not sure, but not yet included
"io_uring: halt SQO submission on ctx exit" may fix it or at least is
related.

> Modules linked in:
> CPU: 1 PID: 53 Comm: kworker/u4:2 Not tainted 5.12.0-rc2-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: events_unbound io_ring_exit_work
> RIP: 0010:__percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113
> Code: fd 49 8d 7c 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 61 49 83 7c 24 10 00 74 07 e8 28 42 ac fd <0f> 0b e8 21 42 ac fd 48 89 ef e8 e9 fa da fd 48 89 da 48 b8 00 00
> RSP: 0018:ffffc90000f1fb78 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffff88805c976000 RCX: 0000000000000000
> RDX: ffff888011839bc0 RSI: ffffffff83c76be8 RDI: ffff88802b2a9010
> RBP: 0000607f46077778 R08: 0000000000000000 R09: ffffffff8fab0967
> R10: ffffffff83c76b88 R11: 0000000000000009 R12: ffff88802b2a9000
> R13: 0000000000000001 R14: ffff88802b2a9000 R15: dffffc0000000000
> FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000085a0004 CR3: 000000001896a000 CR4: 00000000001506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  percpu_ref_exit+0x3b/0x140 lib/percpu-refcount.c:134
>  io_ring_ctx_free fs/io_uring.c:8419 [inline]
>  io_ring_exit_work+0x599/0xcf0 fs/io_uring.c:8565
>  process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
>  worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
>  kthread+0x3b1/0x4a0 kernel/kthread.c:292
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> 
> 
> ---
> 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

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
       [not found] ` <20210318083340.1900-1-hdanton@sina.com>
@ 2021-03-18 14:28   ` Pavel Begunkov
  0 siblings, 0 replies; 11+ messages in thread
From: Pavel Begunkov @ 2021-03-18 14:28 UTC (permalink / raw)
  To: Hillf Danton, Ming Lei
  Cc: syzbot, axboe, io-uring, linux-kernel, syzkaller-bugs

On 18/03/2021 08:33, Hillf Danton wrote:
> On Mon, 15 Mar 2021 12:18:20 +0000 Pavel Begunkov wrote:
>> On 15/03/2021 11:58, syzbot wrote:
>>> Hello,
>>>
>>> syzbot found the following issue on:
>>>
>>> HEAD commit:    75013c6c Merge tag 'perf_urgent_for_v5.12-rc3' of git://gi..
>>> git tree:       upstream
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=174df32ad00000
>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=844457676c06b88c
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
>>> userspace arch: i386
>>>
>>> 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+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com
>>> ------------[ cut here ]------------
>>> WARNING: CPU: 1 PID: 53 at lib/percpu-refcount.c:113 __percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113
>>
>> if (percpu_count) {
>> 	/* non-NULL confirm_switch indicates switching in progress */
>> 	WARN_ON_ONCE(ref->data && ref->data->confirm_switch);
>> 	...
>> }
>>
>> Points to this warning. Not sure, but not yet included
>> "io_uring: halt SQO submission on ctx exit" may fix it or at least is
>> related.
> 
> Seems it does not, nor related, see below.
>>
>>> Modules linked in:
>>> CPU: 1 PID: 53 Comm: kworker/u4:2 Not tainted 5.12.0-rc2-syzkaller #0
>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>>> Workqueue: events_unbound io_ring_exit_work
>>> RIP: 0010:__percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113
>>> Code: fd 49 8d 7c 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 61 49 83 7c 24 10 00 74 07 e8 28 42 ac fd <0f> 0b e8 21 42 ac fd 48 89 ef e8 e9 fa da fd 48 89 da 48 b8 00 00
>>> RSP: 0018:ffffc90000f1fb78 EFLAGS: 00010293
>>> RAX: 0000000000000000 RBX: ffff88805c976000 RCX: 0000000000000000
>>> RDX: ffff888011839bc0 RSI: ffffffff83c76be8 RDI: ffff88802b2a9010
>>> RBP: 0000607f46077778 R08: 0000000000000000 R09: ffffffff8fab0967
>>> R10: ffffffff83c76b88 R11: 0000000000000009 R12: ffff88802b2a9000
>>> R13: 0000000000000001 R14: ffff88802b2a9000 R15: dffffc0000000000
>>> FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
>>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> CR2: 00000000085a0004 CR3: 000000001896a000 CR4: 00000000001506f0
>>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>> Call Trace:
>>>  percpu_ref_exit+0x3b/0x140 lib/percpu-refcount.c:134
>>>  io_ring_ctx_free fs/io_uring.c:8419 [inline]
>>>  io_ring_exit_work+0x599/0xcf0 fs/io_uring.c:8565
>>>  process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
>>>  worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
>>>  kthread+0x3b1/0x4a0 kernel/kthread.c:292
>>>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
>>>
>>>
>>> ---
>>> 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
> 
> Thoughts for sync RCU are appreciated if the chance for the race
> between rcu and workqueue is not zero on killing io ctx.

Would you elaborate? Because your case below doesn't make much
sense.

1) io_ring_ctx_wait_and_kill() indeed kills ctx->refs
2) io_ring_exit_work() waits for a completion signaled by
ctx->refs hitting 0
3) and only then calls io_ring_ctx_free().

And 2) won't complete until the switching is over

> 
> CPU0
> ----
> io_ring_ctx_wait_and_kill
> percpu_ref_kill(&ctx->refs);
> percpu_ref_kill_and_confirm(ref, NULL);
> spin_lock_irqsave(&percpu_ref_switch_lock, flags);
> __percpu_ref_switch_mode(ref, confirm_switch);
>   __percpu_ref_switch_to_atomic
>     ref->data->confirm_switch = confirm_switch ?:
> 		percpu_ref_noop_confirm_switch;
>     call_rcu(&ref->data->rcu, percpu_ref_switch_to_atomic_rcu);
> spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
> 
> INIT_WORK(&ctx->exit_work, io_ring_exit_work);
> queue_work(system_unbound_wq, &ctx->exit_work);
> 
> 						CPU1
> 						----
> 						io_ring_exit_work
> 						io_ring_ctx_free(ctx);
> 						percpu_ref_exit(&ctx->refs);
> 						__percpu_ref_exit(ref);
> 						WARN_ON_ONCE(ref->data &&
> 							ref->data->confirm_switch);
> 
> 
> percpu_ref_switch_to_atomic_rcu
>   percpu_ref_call_confirm_rcu(rcu);
>     data->confirm_switch(ref);
>     data->confirm_switch = NULL;
>     wake_up_all(&percpu_ref_switch_waitq);
> 

-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
  2021-03-15 11:58 [syzbot] WARNING in __percpu_ref_exit (2) syzbot
  2021-03-15 12:18 ` Pavel Begunkov
       [not found] ` <20210318083340.1900-1-hdanton@sina.com>
@ 2021-04-18 19:30 ` syzbot
  2021-04-19 12:07   ` Pavel Begunkov
  2021-09-13  9:22 ` syzbot
  3 siblings, 1 reply; 11+ messages in thread
From: syzbot @ 2021-04-18 19:30 UTC (permalink / raw)
  To: asml.silence, axboe, hdanton, io-uring, linux-kernel, ming.lei,
	syzkaller-bugs

syzbot has found a reproducer for the following issue on:

HEAD commit:    c98ff1d0 Merge tag 'scsi-fixes' of git://git.kernel.org/pu..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=163d7229d00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1c70e618af4c2e92
dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145cb2b6d00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=157b72b1d00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 169 at lib/percpu-refcount.c:113 __percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113
Modules linked in:
CPU: 1 PID: 169 Comm: kworker/u4:3 Not tainted 5.12.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound io_ring_exit_work
RIP: 0010:__percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113
Code: fd 49 8d 7c 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 61 49 83 7c 24 10 00 74 07 e8 a8 4a ab fd <0f> 0b e8 a1 4a ab fd 48 89 ef e8 69 f0 d9 fd 48 89 da 48 b8 00 00
RSP: 0018:ffffc90001077b48 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88802d5ca000 RCX: 0000000000000000
RDX: ffff88801217a1c0 RSI: ffffffff83c7db28 RDI: ffff88801d58f010
RBP: 0000607f4607bcb8 R08: 0000000000000000 R09: ffffffff8fa9f977
R10: ffffffff83c7dac8 R11: 0000000000000009 R12: ffff88801d58f000
R13: 000000010002865e R14: ffff88801d58f000 R15: ffff88802d5ca8b0
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000044 CR3: 0000000015c02000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 percpu_ref_exit+0x3b/0x140 lib/percpu-refcount.c:134
 io_ring_ctx_free fs/io_uring.c:8483 [inline]
 io_ring_exit_work+0xa64/0x12d0 fs/io_uring.c:8620
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294


^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
  2021-04-18 19:30 ` syzbot
@ 2021-04-19 12:07   ` Pavel Begunkov
  2021-04-19 15:02     ` syzbot
  0 siblings, 1 reply; 11+ messages in thread
From: Pavel Begunkov @ 2021-04-19 12:07 UTC (permalink / raw)
  To: syzbot, axboe, hdanton, io-uring, linux-kernel, ming.lei, syzkaller-bugs

On 4/18/21 8:30 PM, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    c98ff1d0 Merge tag 'scsi-fixes' of git://git.kernel.org/pu..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=163d7229d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=1c70e618af4c2e92
> dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145cb2b6d00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=157b72b1d00000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 169 at lib/percpu-refcount.c:113 __percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113
> Modules linked in:
> CPU: 1 PID: 169 Comm: kworker/u4:3 Not tainted 5.12.0-rc7-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: events_unbound io_ring_exit_work
> RIP: 0010:__percpu_ref_exit+0x98/0x100 lib/percpu-refcount.c:113
> Code: fd 49 8d 7c 24 10 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 61 49 83 7c 24 10 00 74 07 e8 a8 4a ab fd <0f> 0b e8 a1 4a ab fd 48 89 ef e8 69 f0 d9 fd 48 89 da 48 b8 00 00
> RSP: 0018:ffffc90001077b48 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffff88802d5ca000 RCX: 0000000000000000
> RDX: ffff88801217a1c0 RSI: ffffffff83c7db28 RDI: ffff88801d58f010
> RBP: 0000607f4607bcb8 R08: 0000000000000000 R09: ffffffff8fa9f977
> R10: ffffffff83c7dac8 R11: 0000000000000009 R12: ffff88801d58f000
> R13: 000000010002865e R14: ffff88801d58f000 R15: ffff88802d5ca8b0
> FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020000044 CR3: 0000000015c02000 CR4: 00000000001506e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  percpu_ref_exit+0x3b/0x140 lib/percpu-refcount.c:134
>  io_ring_ctx_free fs/io_uring.c:8483 [inline]
>  io_ring_exit_work+0xa64/0x12d0 fs/io_uring.c:8620
>  process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
>  worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
>  kthread+0x3b1/0x4a0 kernel/kthread.c:292
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> 

#syz test: git://git.kernel.dk/linux-block for-5.13/io_uring

-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
  2021-04-19 12:07   ` Pavel Begunkov
@ 2021-04-19 15:02     ` syzbot
  0 siblings, 0 replies; 11+ messages in thread
From: syzbot @ 2021-04-19 15:02 UTC (permalink / raw)
  To: asml.silence, axboe, hdanton, io-uring, linux-kernel, ming.lei,
	syzkaller-bugs

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com

Tested on:

commit:         75c4021a io_uring: check register restriction afore quiesce
git tree:       git://git.kernel.dk/linux-block for-5.13/io_uring
kernel config:  https://syzkaller.appspot.com/x/.config?x=1dfd9a1e63100694
dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
compiler:       

Note: testing is done by a robot and is best-effort only.

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
  2021-03-15 11:58 [syzbot] WARNING in __percpu_ref_exit (2) syzbot
                   ` (2 preceding siblings ...)
  2021-04-18 19:30 ` syzbot
@ 2021-09-13  9:22 ` syzbot
  2021-09-16  7:59   ` Dmitry Vyukov
  3 siblings, 1 reply; 11+ messages in thread
From: syzbot @ 2021-09-13  9:22 UTC (permalink / raw)
  To: asml.silence, axboe, coreteam, davem, dsahern, fw, hdanton,
	io-uring, kadlec, kuba, linux-kernel, ming.lei, netdev,
	netfilter-devel, pablo, syzkaller-bugs, yoshfuji

syzbot suspects this issue was fixed by commit:

commit 43016d02cf6e46edfc4696452251d34bba0c0435
Author: Florian Westphal <fw@strlen.de>
Date:   Mon May 3 11:51:15 2021 +0000

    netfilter: arptables: use pernet ops struct during unregister

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=10acd273300000
start commit:   c98ff1d013d2 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree:       upstream
kernel config:  https://syzkaller.appspot.com/x/.config?x=1c70e618af4c2e92
dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145cb2b6d00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=157b72b1d00000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: netfilter: arptables: use pernet ops struct during unregister

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

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
  2021-09-13  9:22 ` syzbot
@ 2021-09-16  7:59   ` Dmitry Vyukov
  2021-09-16 13:17     ` Pavel Begunkov
  0 siblings, 1 reply; 11+ messages in thread
From: Dmitry Vyukov @ 2021-09-16  7:59 UTC (permalink / raw)
  To: syzbot
  Cc: asml.silence, axboe, coreteam, davem, dsahern, fw, hdanton,
	io-uring, kadlec, kuba, linux-kernel, ming.lei, netdev,
	netfilter-devel, pablo, syzkaller-bugs, yoshfuji

On Mon, 13 Sept 2021 at 11:22, syzbot
<syzbot+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com> wrote:
>
> syzbot suspects this issue was fixed by commit:
>
> commit 43016d02cf6e46edfc4696452251d34bba0c0435
> Author: Florian Westphal <fw@strlen.de>
> Date:   Mon May 3 11:51:15 2021 +0000
>
>     netfilter: arptables: use pernet ops struct during unregister
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=10acd273300000
> start commit:   c98ff1d013d2 Merge tag 'scsi-fixes' of git://git.kernel.or..
> git tree:       upstream
> kernel config:  https://syzkaller.appspot.com/x/.config?x=1c70e618af4c2e92
> dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145cb2b6d00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=157b72b1d00000
>
> If the result looks correct, please mark the issue as fixed by replying with:
>
> #syz fix: netfilter: arptables: use pernet ops struct during unregister
>
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection

I guess this is a wrong commit and it was fixed by something in io_uring.
Searching for refcount fixes I see
a298232ee6b9a1d5d732aa497ff8be0d45b5bd82 "io_uring: fix link timeout
refs".
Pavel, does it look right to you?

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
  2021-09-16  7:59   ` Dmitry Vyukov
@ 2021-09-16 13:17     ` Pavel Begunkov
  2021-09-16 14:01       ` syzbot
  0 siblings, 1 reply; 11+ messages in thread
From: Pavel Begunkov @ 2021-09-16 13:17 UTC (permalink / raw)
  To: Dmitry Vyukov, syzbot
  Cc: axboe, coreteam, davem, dsahern, fw, hdanton, io-uring, kadlec,
	kuba, linux-kernel, ming.lei, netdev, netfilter-devel, pablo,
	syzkaller-bugs, yoshfuji

On 9/16/21 8:59 AM, Dmitry Vyukov wrote:
> On Mon, 13 Sept 2021 at 11:22, syzbot
> <syzbot+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com> wrote:
>>
>> syzbot suspects this issue was fixed by commit:
>>
>> commit 43016d02cf6e46edfc4696452251d34bba0c0435
>> Author: Florian Westphal <fw@strlen.de>
>> Date:   Mon May 3 11:51:15 2021 +0000
>>
>>     netfilter: arptables: use pernet ops struct during unregister
>>
>> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=10acd273300000
>> start commit:   c98ff1d013d2 Merge tag 'scsi-fixes' of git://git.kernel.or..
>> git tree:       upstream
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=1c70e618af4c2e92
>> dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145cb2b6d00000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=157b72b1d00000
>>
>> If the result looks correct, please mark the issue as fixed by replying with:
>>
>> #syz fix: netfilter: arptables: use pernet ops struct during unregister
>>
>> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> 
> I guess this is a wrong commit and it was fixed by something in io_uring.
> Searching for refcount fixes I see
> a298232ee6b9a1d5d732aa497ff8be0d45b5bd82 "io_uring: fix link timeout
> refs".
> Pavel, does it look right to you?

I don't remember to be honest, if the dates fit, it can pretty well be it.
Let's test one thing to be sure it hasn't been shut just by coincidence.

#syz test: https://github.com/isilence/linux.git syz_test_quiesce_files


-- 
Pavel Begunkov

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
  2021-09-16 13:17     ` Pavel Begunkov
@ 2021-09-16 14:01       ` syzbot
  2021-09-20  8:15         ` Dmitry Vyukov
  0 siblings, 1 reply; 11+ messages in thread
From: syzbot @ 2021-09-16 14:01 UTC (permalink / raw)
  To: asml.silence, axboe, coreteam, davem, dsahern, dvyukov, fw,
	hdanton, io-uring, kadlec, kuba, linux-kernel, ming.lei, netdev,
	netfilter-devel, pablo, syzkaller-bugs, yoshfuji

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com

Tested on:

commit:         5318e5b9 io_uring: quiesce files reg
git tree:       https://github.com/isilence/linux.git syz_test_quiesce_files
kernel config:  https://syzkaller.appspot.com/x/.config?x=f7d9f99709463d21
dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Note: testing is done by a robot and is best-effort only.

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [syzbot] WARNING in __percpu_ref_exit (2)
  2021-09-16 14:01       ` syzbot
@ 2021-09-20  8:15         ` Dmitry Vyukov
  0 siblings, 0 replies; 11+ messages in thread
From: Dmitry Vyukov @ 2021-09-20  8:15 UTC (permalink / raw)
  To: syzbot
  Cc: asml.silence, axboe, coreteam, davem, dsahern, fw, hdanton,
	io-uring, kadlec, kuba, linux-kernel, ming.lei, netdev,
	netfilter-devel, pablo, syzkaller-bugs, yoshfuji

On Thu, 16 Sept 2021 at 16:01, syzbot
<syzbot+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot has tested the proposed patch and the reproducer did not trigger any issue:
>
> Reported-and-tested-by: syzbot+d6218cb2fae0b2411e9d@syzkaller.appspotmail.com
>
> Tested on:
>
> commit:         5318e5b9 io_uring: quiesce files reg
> git tree:       https://github.com/isilence/linux.git syz_test_quiesce_files
> kernel config:  https://syzkaller.appspot.com/x/.config?x=f7d9f99709463d21
> dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
> compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
>
> Note: testing is done by a robot and is best-effort only.

OK, since it's not failing, I assume we can say:

#syz fix: io_uring: fix link timeout refs

(and it's better to close it with a wrong fix, then to keep it open
forever anyway)

^ permalink raw reply	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2021-09-20  8:15 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-03-15 11:58 [syzbot] WARNING in __percpu_ref_exit (2) syzbot
2021-03-15 12:18 ` Pavel Begunkov
     [not found] ` <20210318083340.1900-1-hdanton@sina.com>
2021-03-18 14:28   ` Pavel Begunkov
2021-04-18 19:30 ` syzbot
2021-04-19 12:07   ` Pavel Begunkov
2021-04-19 15:02     ` syzbot
2021-09-13  9:22 ` syzbot
2021-09-16  7:59   ` Dmitry Vyukov
2021-09-16 13:17     ` Pavel Begunkov
2021-09-16 14:01       ` syzbot
2021-09-20  8:15         ` Dmitry Vyukov

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