linux-kernel - Re: [PATCH v2 1/4] mm/hwpoison: mf_mutex for soft offline and unpoison

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Message-ID: <20211027023119.GC2707645@u2004>
Date:   Wed, 27 Oct 2021 11:31:19 +0900
From:   Naoya Horiguchi <naoya.horiguchi@...ux.dev>
To:     Yang Shi <shy828301@...il.com>
Cc:     Linux MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Oscar Salvador <osalvador@...e.de>,
        Michal Hocko <mhocko@...e.com>,
        Ding Hui <dinghui@...gfor.com.cn>,
        Tony Luck <tony.luck@...el.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Peter Xu <peterx@...hat.com>,
        Naoya Horiguchi <naoya.horiguchi@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/4] mm/hwpoison: mf_mutex for soft offline and
 unpoison

On Tue, Oct 26, 2021 at 06:32:36PM -0700, Yang Shi wrote:
> On Mon, Oct 25, 2021 at 4:06 PM Naoya Horiguchi
> <naoya.horiguchi@...ux.dev> wrote:
> >
> > From: Naoya Horiguchi <naoya.horiguchi@....com>
> >
> > Originally mf_mutex is introduced to serialize multiple MCE events, but
> > it's also helpful to exclude races among  soft_offline_page() and
> > unpoison_memory().  So apply mf_mutex to them.
> 
> My understanding is it is not that useful to make unpoison run
> parallel with memory_failure() and soft offline, so they can be
> serialized by mf_mutex and we could make the memory failure handler
> and soft offline simpler.

Thank you for the suggestion, this sounds correct and more specific.

> 
> If the above statement is correct, could you please tweak this commit
> log to reflect it with patch #2 squashed into this patch?

Sure, I'm thinking of revising like below:

  Originally mf_mutex is introduced to serialize multiple MCE events, but
  it is not that useful to allow unpoison to run in parallel with memory_failure()
  and soft offline.  So apply mf_they to soft offline and unpoison.
  The memory failure handler and soft offline handler get simpler with this.

Thanks,
Naoya Horiguchi