From: David Teigland <teigland@redhat.com>
To: Jia-Ju Bai <baijiaju1990@gmail.com>
Cc: cluster-devel@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [BUG] fs: dlm: possible ABBA deadlock
Date: Thu, 19 Aug 2021 10:55:09 -0500 [thread overview]
Message-ID: <20210819155509.GB21218@redhat.com> (raw)
In-Reply-To: <79f8d302-f53f-3891-965a-bcb460ab15ca@gmail.com>
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
next prev parent reply other threads:[~2021-08-19 15:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-19 8:54 [BUG] fs: dlm: possible ABBA deadlock Jia-Ju Bai
2021-08-19 15:55 ` David Teigland [this message]
2021-08-20 8:16 ` Jia-Ju Bai
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