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a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1681336639; bh=6pRvLGc87JTXtP4muzgwevPzgBKLZDkUknq8v/ar9Ik=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=NcieaChHyrNGnCn7GnJNkduQweAwfHG4D+WlMj0KByLMYkb+Yw5eawpuWpyDke/vp Jsf7xKCznL2j0yKer+6MO1ryeP1EfxxFG3yJT2IxKN0riQOmQtyzBSbL70eve4O771 taqdi4LjEi0Jks86rFGfNpz/4hB6flnEUQzCwjGY= Date: Wed, 12 Apr 2023 14:57:18 -0700 From: Andrew Morton To: Mike Kravetz Cc: Liu Shixin , Naoya Horiguchi , Tony Luck , Miaohe Lin , Muchun Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -next] mm: hwpoison: support recovery from HugePage copy-on-write faults Message-Id: <20230412145718.0bcb7dd98112a3010711ad0b@linux-foundation.org> In-Reply-To: <20230412181350.GA22818@monkey> References: <20230411092741.780679-1-liushixin2@huawei.com> <20230412181350.GA22818@monkey> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: E7A411C0005 X-Rspamd-Server: rspam01 X-Stat-Signature: azd63qnuizx6qq1hcj1ou84ybttiadbi X-HE-Tag: 1681336640-610062 X-HE-Meta: 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 D/fy/SWE 4muF9vcCcDakwhZDsdKmMgUeeHiaclNc3L8kOJuTi2DiSpDykt4JFAYKH7GO1/mx/EuZmvt5NUmumW3ArCAbmMsnkwV3A1qFwhRdO2/FIQXgymTwHd+E8wQ2OzY/VWT7Gv5+gHPNwIlXhR3f8xjjmqSLvW8FeEjYzGSlRX8k8klDhSAvTFDu8wiY3yp6NlSTrqQyv0hEhn7kSuaW/+XgM+CO/98vtL1R+Ctu29ip5LtLNuoyGFFPFCulZdan4sfdfIcCPfo/UMYCs7ZTU2qzy0UAGg6XySqdVQJJhENHXqJG2DzjIplEJYvGnG7x7x2teVSSeaTKsIaMqxy0tu6bK4PYOeki6AGZELAWBwM1+WNmTkSct2+7CtGKb3g== 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 Wed, 12 Apr 2023 11:13:50 -0700 Mike Kravetz wrote: > On 04/11/23 17:27, Liu Shixin wrote: > > Patch a873dfe1032a ("mm, hwpoison: try to recover from copy-on write faults") > > introduced a new copy_user_highpage_mc() function, and fix the kernel crash > > when the kernel is copying a normal page as the result of a copy-on-write > > fault and runs into an uncorrectable error. But it doesn't work for HugeTLB. > > Andrew asked about user-visible effects. Perhaps, a better way of > stating this in the commit message might be: > > Commit a873dfe1032a ("mm, hwpoison: try to recover from copy-on write > faults") introduced the routine copy_user_highpage_mc() to gracefully > handle copying of user pages with uncorrectable errors. Previously, > such copies would result in a kernel crash. hugetlb has separate code > paths for copy-on-write and does not benefit from the changes made in > commit a873dfe1032a. > > Modify hugetlb copy-on-write code paths to use copy_mc_user_highpage() > so that they can also gracefully handle uncorrectable errors in user > pages. This involves changing the hugetlb specific routine > ?copy_user_folio()? from type void to int so that it can return an error. > Modify the hugetlb userfaultfd code in the same way so that it can return > -EHWPOISON if it encounters an uncorrectable error. Thanks, but... what are the runtime effects? What does hugetlb presently do when encountering these uncorrectable error?