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From: "HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>
To: David Hildenbrand <david@redhat.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Miaohe Lin <linmiaohe@huawei.com>,
	Liu Shixin <liushixin2@huawei.com>,
	Yang Shi <shy828301@gmail.com>,
	Oscar Salvador <osalvador@suse.de>,
	Muchun Song <songmuchun@bytedance.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 1/5] mm, hwpoison, hugetlb: introduce SUBPAGE_INDEX_HWPOISON to save raw error page
Date: Wed, 8 Jun 2022 01:31:30 +0000	[thread overview]
Message-ID: <20220608013125.GA1404644@hori.linux.bs1.fc.nec.co.jp> (raw)
In-Reply-To: <ea4cc6c8-a772-dce0-a7a3-4c3ceb31735f@redhat.com>

On Tue, Jun 07, 2022 at 03:04:15PM +0200, David Hildenbrand wrote:
> On 02.06.22 07:06, Naoya Horiguchi wrote:
> > From: Naoya Horiguchi <naoya.horiguchi@nec.com>
> > 
> > When handling memory error on a hugetlb page, the error handler tries to
> > dissolve and turn it into 4kB pages.  If it's successfully dissolved,
> > PageHWPoison flag is moved to the raw error page, so that's all right.
> > However, dissolve sometimes fails, then the error page is left as
> > hwpoisoned hugepage. It's useful if we can retry to dissolve it to save
> > healthy pages, but that's not possible now because the information about
> > where the raw error page is lost.
> > 
> > Use the private field of a tail page to keep that information.  The code
> > path of shrinking hugepage pool used this info to try delayed dissolve.
> > This only keeps one hwpoison page for now, which might be OK because it's
> > simple and multiple hwpoison pages in a hugepage can be rare. But it can
> > be extended in the future.
> > 
> >
> 
> But what would happen now if you have multiple successive MCE events on
> such a page now?

The 2nd and later events are ignored due to "already hwpoisoned hugepage",
this might not be good when the hwpoisoned hugepage is freed/dissolved later.
So a temporal workaround is to remember "hugepage has multiple hwpoison pages"
and disable free/dissolve for such hugepages.

Thanks,
Naoya Horiguchi

  reply	other threads:[~2022-06-08  1:31 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-02  5:06 [PATCH v1 0/5] mm, hwpoison: enable 1GB hugepage support Naoya Horiguchi
2022-06-02  5:06 ` [PATCH v1 1/5] mm, hwpoison, hugetlb: introduce SUBPAGE_INDEX_HWPOISON to save raw error page Naoya Horiguchi
2022-06-07 12:45   ` Miaohe Lin
2022-06-07 13:04   ` David Hildenbrand
2022-06-08  1:31     ` HORIGUCHI NAOYA(堀口 直也) [this message]
2022-06-08  9:19       ` David Hildenbrand
2022-06-02  5:06 ` [PATCH v1 2/5] mm,hwpoison: set PG_hwpoison for busy hugetlb pages Naoya Horiguchi
2022-06-07 12:50   ` Miaohe Lin
2022-06-02  5:06 ` [PATCH v1 3/5] mm, hwpoison: make __page_handle_poison returns int Naoya Horiguchi
2022-06-07 12:54   ` Miaohe Lin
2022-06-08  1:40     ` HORIGUCHI NAOYA(堀口 直也)
2022-06-02  5:06 ` [PATCH v1 4/5] mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage Naoya Horiguchi
2022-06-07 13:56   ` Miaohe Lin
2022-06-02  5:06 ` [PATCH v1 5/5] mm, hwpoison: enable memory error handling on " Naoya Horiguchi
2022-06-07 14:11   ` Miaohe Lin
2022-06-08  6:16     ` HORIGUCHI NAOYA(堀口 直也)
2022-06-08 12:57       ` Miaohe Lin
2022-06-09  8:45         ` HORIGUCHI NAOYA(堀口 直也)
2022-06-09 11:28           ` Miaohe Lin

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