* [BUG] fs: dlm: possible ABBA deadlock
@ 2021-08-19 8:54 Jia-Ju Bai
2021-08-19 15:55 ` David Teigland
0 siblings, 1 reply; 3+ messages in thread
From: Jia-Ju Bai @ 2021-08-19 8:54 UTC (permalink / raw)
To: ccaulfie, teigland; +Cc: cluster-devel, linux-kernel
Hello,
My static analysis tool reports a possible ABBA deadlock in the dlm
filesystem in Linux 5.10:
dlm_recover_waiters_pre()
mutex_lock(&ls->ls_waiters_mutex); --> line 5130
recover_convert_waiter()
_receive_convert_reply()
lock_rsb()
mutex_lock(&r->res_mutex); --> line 69
dlm_recover_waiters_post()
lock_rsb()
mutex_lock(&r->res_mutex); --> line 69
mutex_lock(&ls->ls_waiters_mutex); --> line 5307
When dlm_recover_waiters_pre() and dlm_recover_waiters_post() are
concurrently executed, the deadlock can occur.
I am not quite sure whether this possible deadlock is real and how to
fix it if it is real.
Any feedback would be appreciated, thanks :)
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Best wishes,
Jia-Ju Bai
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [BUG] fs: dlm: possible ABBA deadlock
2021-08-19 8:54 [BUG] fs: dlm: possible ABBA deadlock Jia-Ju Bai
@ 2021-08-19 15:55 ` David Teigland
2021-08-20 8:16 ` Jia-Ju Bai
0 siblings, 1 reply; 3+ messages in thread
From: David Teigland @ 2021-08-19 15:55 UTC (permalink / raw)
To: Jia-Ju Bai; +Cc: cluster-devel, linux-kernel
On Thu, Aug 19, 2021 at 04:54:57PM +0800, Jia-Ju Bai wrote:
> Hello,
>
> My static analysis tool reports a possible ABBA deadlock in the dlm
> filesystem in Linux 5.10:
>
> dlm_recover_waiters_pre()
> mutex_lock(&ls->ls_waiters_mutex); --> line 5130
> recover_convert_waiter()
> _receive_convert_reply()
> lock_rsb()
> mutex_lock(&r->res_mutex); --> line 69
>
> dlm_recover_waiters_post()
> lock_rsb()
> mutex_lock(&r->res_mutex); --> line 69
> mutex_lock(&ls->ls_waiters_mutex); --> line 5307
>
> When dlm_recover_waiters_pre() and dlm_recover_waiters_post() are
> concurrently executed, the deadlock can occur.
>
> I am not quite sure whether this possible deadlock is real and how to fix it
> if it is real.
> Any feedback would be appreciated, thanks :)
They won't be concurrent, "pre" runs before recovery, and "post" is after.
Dave
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [BUG] fs: dlm: possible ABBA deadlock
2021-08-19 15:55 ` David Teigland
@ 2021-08-20 8:16 ` Jia-Ju Bai
0 siblings, 0 replies; 3+ messages in thread
From: Jia-Ju Bai @ 2021-08-20 8:16 UTC (permalink / raw)
To: David Teigland; +Cc: cluster-devel, linux-kernel
On 2021/8/19 23:55, David Teigland wrote:
> On Thu, Aug 19, 2021 at 04:54:57PM +0800, Jia-Ju Bai wrote:
>> Hello,
>>
>> My static analysis tool reports a possible ABBA deadlock in the dlm
>> filesystem in Linux 5.10:
>>
>> dlm_recover_waiters_pre()
>> mutex_lock(&ls->ls_waiters_mutex); --> line 5130
>> recover_convert_waiter()
>> _receive_convert_reply()
>> lock_rsb()
>> mutex_lock(&r->res_mutex); --> line 69
>>
>> dlm_recover_waiters_post()
>> lock_rsb()
>> mutex_lock(&r->res_mutex); --> line 69
>> mutex_lock(&ls->ls_waiters_mutex); --> line 5307
>>
>> When dlm_recover_waiters_pre() and dlm_recover_waiters_post() are
>> concurrently executed, the deadlock can occur.
>>
>> I am not quite sure whether this possible deadlock is real and how to fix it
>> if it is real.
>> Any feedback would be appreciated, thanks :)
> They won't be concurrent, "pre" runs before recovery, and "post" is after.
Okay, thanks for your reply :)
Best wishes,
Jia-Ju Bai
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-08-19 15:55 ` David Teigland
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