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[2003:cb:c709:500:4c8d:4886:f874:7b6f]) by smtp.gmail.com with ESMTPSA id bp3-20020a5d5a83000000b0020cff559b1dsm17827729wrb.47.2022.06.07.06.04.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Jun 2022 06:04:28 -0700 (PDT) Message-ID: Date: Tue, 7 Jun 2022 15:04:15 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v1 1/5] mm, hwpoison, hugetlb: introduce SUBPAGE_INDEX_HWPOISON to save raw error page To: Naoya Horiguchi , linux-mm@kvack.org Cc: Andrew Morton , Mike Kravetz , Miaohe Lin , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , Naoya Horiguchi , linux-kernel@vger.kernel.org References: <20220602050631.771414-1-naoya.horiguchi@linux.dev> <20220602050631.771414-2-naoya.horiguchi@linux.dev> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20220602050631.771414-2-naoya.horiguchi@linux.dev> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 062E9140055 X-Stat-Signature: 7zbjggp53pu3wqqsif6nydqohqj3oxjt X-Rspam-User: Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=cMoSLRhB; spf=none (imf23.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-HE-Tag: 1654607055-175604 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 02.06.22 07:06, Naoya Horiguchi wrote: > From: Naoya Horiguchi > > 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? -- Thanks, David / dhildenb