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bh=1O/8VJdwC6exTtvaS31U9tPVXqQob2pb5H8yDpg2h4Y=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=vABntK2I8QKsI+0yaF7DesF+cF4ljqLZYifsghCGmVHxBmiQ95zGZS3qYrH39NxwM sGO15KX24Zh35lv60lXUqlttfQxZ2leJN8butFLzzH3CaOSxXkolNPeDqAyiC8WFv+ aT2CKd7AoFCPsw4o8yZEfDTm0EZZy7e1rWRcdq+w= Date: Wed, 12 Apr 2023 15:56:18 -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: <20230412155618.720e6b3aa5be6444f7889ea6@linux-foundation.org> In-Reply-To: <20230412222138.GB4759@monkey> References: <20230411092741.780679-1-liushixin2@huawei.com> <20230412181350.GA22818@monkey> <20230412145718.0bcb7dd98112a3010711ad0b@linux-foundation.org> <20230412222138.GB4759@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-Server: rspam02 X-Rspamd-Queue-Id: 069854001F X-Stat-Signature: pwmy5qpxrg1omd7pht7o5nesbojqcqpm X-HE-Tag: 1681340180-791082 X-HE-Meta: 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 RRP8S7FD Y3IUVJtSX0OeTpawsgSV/Q47H+uCcAwkFZxeAUc4/t87/w4WdNgPm1DAPXK/WaPaiUzF/smzQx3j3ZvMlbbGUrJ958aKi3V7xktmhL8nBUo9nUp9lUJgtx/Twx8U2A37rofpPkYZKv0yD/5jLZUjzMQdnH64ozPr2d1+hUnOR0bjYsfWi36sqawdjfyQD7O18T4lEyTBGh4vlmtLkVhN5DfW2hYVmiAO4UYcLmCmpqg7dZP6lz+j+BkWWcBLFm1KLkC0M5zW4nb4oyTVr/sD9qHWMiaH89JFsmVlEMn10tNJ8ls3pbYaLJUi+WH/BC6o1WucuQ13r8wfQdgEiLNaH/TlinAcKyneegQDIn3/Id5R2HsJJEAh/O2ypNg== 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 15:21:38 -0700 Mike Kravetz wrote: > > > 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. > > I was just going to suggest adding the line, > > Hence, copy-on-write of hugetlb user pages with uncorrectable errors > will result in a kernel crash as was the case with 'normal' pages before > commit a873dfe1032a. > > However, I'm guessing it might be more clear if we start with the > runtime effects. Something like: > > copy-on-write of hugetlb user pages with uncorrectable errors will result > in a kernel crash. This is because the copy is performed in kernel mode > and in general we can not handle accessing memory with such errors while > in kernel mode. 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. However, > the separate hugetlb copy-on-write code paths were not modified as part > of commit a873dfe1032a. Sounds good. So I assume cc:stable is desirable. I can't actually get the patch to apply to anything. Can we please have a redo against current -linus?