linux-kernel - Re: [PATCH] kexec: change locking mechanism to a mutex

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Message-ID: <48c5e937-f9c2-327d-c823-a91826ed146f@oracle.com>
Date:   Thu, 21 Sep 2023 20:00:14 -0500
From:   Eric DeVolder <eric.devolder@...cle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, bhe@...hat.com, vgoyal@...hat.com,
        dyoung@...hat.com, ebiederm@...ssion.com,
        kexec@...ts.infradead.org, sourabhjain@...ux.ibm.com,
        konrad.wilk@...cle.com, boris.ostrovsky@...cle.com
Subject: Re: [PATCH] kexec: change locking mechanism to a mutex



On 9/21/23 19:22, Andrew Morton wrote:
> On Thu, 21 Sep 2023 17:59:38 -0400 Eric DeVolder <eric.devolder@...cle.com> wrote:
> 
>> Scaled up testing has revealed that the kexec_trylock()
>> implementation leads to failures within the crash hotplug
>> infrastructure due to the inability to acquire the lock,
>> specifically the message:
>>
>> ...
>>
>> Convert the atomic lock to a mutex.
>>
> 
> Do you think this problem is serious enough to warrant a backport into
> -stable kernels?

I do not since it will be the lock traffic created by the crash hotplug infrastructure that will 
reveal the weak locking mechanism. Until this crash hotplug shows up in a stable kernel, it should 
not be an issue; there isn't anything else that easily exercise it to reveal the problem.

eric