Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 15 Jun 2022 07:52:06 +0200
From:   Oscar Salvador <osalvador@suse.de>
To:     zhenwei pi <pizhenwei@bytedance.com>
Cc:     naoya.horiguchi@nec.com, akpm@linux-foundation.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@redhat.com,
        linmiaohe@huawei.com, gregkh@linuxfoundation.org
Subject: Re: Re: [PATCH v5 1/1] mm/memory-failure: disable unpoison once hw
 error happens
Message-ID: <YqlzhlrjJhqvUV4I@localhost.localdomain>
References: <20220615020005.246295-1-pizhenwei@bytedance.com>
 <20220615020005.246295-2-pizhenwei@bytedance.com>
 <Yqle3M18fuEJE0qn@localhost.localdomain>
 <dbe19d10-beb1-bbdc-7935-3e1cfa46e3e8@bytedance.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <dbe19d10-beb1-bbdc-7935-3e1cfa46e3e8@bytedance.com>
Precedence: bulk

On Wed, Jun 15, 2022 at 01:18:23PM +0800, zhenwei pi wrote:
> Hi,
> 
> Because memory_failure() may be called by hardware error randomly,
> hw_memory_failure should be protected by mf_mutex to avoid this case:
> int unpoison_memory(unsigned long pfn)
> {
>     ...
>     if (hw_memory_failure) {
>     }
>     ... --> memory_failure() happens, and mark hw_memory_failure as true
>     mutex_lock(&mf_mutex);

Yeah, I am aware of that.
But once memory_failure() sets hw_memory_failure to true, it does not really matter
whether unpoison_memory() checks that while holding or not the lock, does it?

Note that it does not really matter in the end, but I am just curious whether
there is any strong impediment to that. 


-- 
Oscar Salvador
SUSE Labs