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To: Aili Yao , akpm@linux-foundation.org, naoya.horiguchi@nec.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, yangfeng1@kingsoft.com, sunhao2@kingsoft.com, Oscar Salvador , Mike Kravetz References: <20210317163714.328a038d@alex-virtual-machine> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: <20a0d078-f49d-54d6-9f04-f6b41dd51e5f@redhat.com> Date: Wed, 17 Mar 2021 10:12:02 +0100 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: <20210317163714.328a038d@alex-virtual-machine> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Stat-Signature: jp67ijmq8dtj9rjbqsj17e5aunq96mtk X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 5443EC0001EA Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf14; identity=mailfrom; envelope-from=""; helo=us-smtp-delivery-124.mimecast.com; client-ip=216.205.24.124 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615972330-769300 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 17.03.21 09:37, Aili Yao wrote: > When we do coredump for user process signal, this may be an SIGBUS signal > with BUS_MCEERR_AR or BUS_MCEERR_AO code, which means this signal is > resulted from ECC memory fail like SRAR or SRAO, we expect the memory > recovery work is finished correctly, then the get_dump_page() will not > return the error page as its process pte is set invalid by > memory_failure(). > > But memory_failure() may fail, and the process's related pte may not be > correctly set invalid, for current code, we will return the poison page > and get it dumped and lead to system panic as its in kernel code. > > So check the poison status in get_dump_page(), and if TRUE, return NULL. > > Signed-off-by: Aili Yao > --- > mm/gup.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/mm/gup.c b/mm/gup.c > index e4c224c..499a496 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1536,6 +1536,14 @@ struct page *get_dump_page(unsigned long addr) > FOLL_FORCE | FOLL_DUMP | FOLL_GET); > if (locked) > mmap_read_unlock(mm); > + > + if (IS_ENABLED(CONFIG_MEMORY_FAILURE) && ret == 1) { > + if (unlikely(PageHuge(page) && PageHWPoison(compound_head(page)))) > + ret = 0; > + else if (unlikely(PageHWPoison(page))) > + ret = 0; > + } I wonder if a simple if (PageHWPoison(compound_head(page))) ret = 0; won't suffice. But I guess the "issue" is compound pages that are not huge pages or transparent huge pages. If not, we certainly want a wrapper for that magic, otherwise we have to replicate the same logic all over the place. > + > return (ret == 1) ? page : NULL; > } > #endif /* CONFIG_ELF_CORE */ > -- Thanks, David / dhildenb