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To: =?UTF-8?B?SE9SSUdVQ0hJIE5BT1lBKOWggOWPoyDnm7TkuZ8p?= , Matthew Wilcox Cc: Aili Yao , "akpm@linux-foundation.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "yangfeng1@kingsoft.com" , "sunhao2@kingsoft.com" , Oscar Salvador , Mike Kravetz References: <20a0d078-f49d-54d6-9f04-f6b41dd51e5f@redhat.com> <20210318044600.GJ3420@casper.infradead.org> <20210318133412.12078eb7@alex-virtual-machine> <20210319104437.6f30e80d@alex-virtual-machine> <20210320003516.GC3420@casper.infradead.org> <20210322193318.377c9ce9@alex-virtual-machine> <20210331015258.GB22060@hori.linux.bs1.fc.nec.co.jp> <20210331060739.GW351017@casper.infradead.org> <20210331065341.GA28793@hori.linux.bs1.fc.nec.co.jp> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Wed, 31 Mar 2021 09:05:06 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210331065341.GA28793@hori.linux.bs1.fc.nec.co.jp> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Rspamd-Queue-Id: 4524440002D0 X-Stat-Signature: 44psxi9a7j19jhmwktex6kxuapkytzpk X-Rspamd-Server: rspam02 Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf10; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=63.128.21.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617174316-283573 Content-Transfer-Encoding: quoted-printable 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 31.03.21 08:53, HORIGUCHI NAOYA(=E5=A0=80=E5=8F=A3 =E7=9B=B4=E4=B9=9F)= wrote: > On Wed, Mar 31, 2021 at 07:07:39AM +0100, Matthew Wilcox wrote: >> On Wed, Mar 31, 2021 at 01:52:59AM +0000, HORIGUCHI NAOYA(=E5=A0=80=E5= =8F=A3 =E7=9B=B4=E4=B9=9F) wrote: >>> If we successfully unmapped but failed in truncate_error_page() for e= xample, >>> the processes mapping the page would get -EFAULT as expected. But ev= en in >>> this case, other processes could reach the error page via page cache = and >>> __get_user_pages_locked() for them could return the hwpoisoned page. >> >> How would that happen? We check PageHWPoison before inserting a page >> into the page tables. See, eg, filemap_map_pages() and __do_fault(). >=20 > Ah, you're right, that never happens. I misread the code. > Thanks for correcting me. >=20 I'm wondering if there is a small race window, if we poison a page while=20 inserting it. --=20 Thanks, David / dhildenb