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From: David Hildenbrand To: Aili Yao , Matthew Wilcox , 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> <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> Organization: Red Hat GmbH Message-ID: Date: Fri, 26 Mar 2021 15:22:49 +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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Stat-Signature: jo9ug4yf3o7zncarrqnynyntoub558n9 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 1A32EC001C4A Received-SPF: none (redhat.com>: No applicable sender policy available) receiver=imf06; 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: 1616768579-867587 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 26.03.21 15:09, David Hildenbrand wrote: > On 22.03.21 12:33, Aili Yao wrote: >> When we do coredump for user process signal, this may be one 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, >> get it dumped, and then lead to system panic as its in kernel code. >> >> So check the hwpoison status in get_dump_page(), and if TRUE, return NULL. >> >> There maybe other scenario that is also better to check hwposion status >> and not to panic, so make a wrapper for this check, Thanks to David's >> suggestion(). >> >> Link: https://lkml.kernel.org/r/20210319104437.6f30e80d@alex-virtual-machine >> Signed-off-by: Aili Yao >> Cc: David Hildenbrand >> Cc: Matthew Wilcox >> Cc: Naoya Horiguchi >> Cc: Oscar Salvador >> Cc: Mike Kravetz >> Cc: Aili Yao >> Cc: stable@vger.kernel.org >> Signed-off-by: Andrew Morton >> --- >> mm/gup.c | 4 ++++ >> mm/internal.h | 20 ++++++++++++++++++++ >> 2 files changed, 24 insertions(+) >> >> diff --git a/mm/gup.c b/mm/gup.c >> index e4c224c..6f7e1aa 100644 >> --- a/mm/gup.c >> +++ b/mm/gup.c >> @@ -1536,6 +1536,10 @@ struct page *get_dump_page(unsigned long addr) >> FOLL_FORCE | FOLL_DUMP | FOLL_GET); >> if (locked) >> mmap_read_unlock(mm); > > Thinking again, wouldn't we get -EFAULT from __get_user_pages_locked() > when stumbling over a hwpoisoned page? > > See __get_user_pages_locked()->__get_user_pages()->faultin_page(): > > handle_mm_fault()->vm_fault_to_errno(), which translates > VM_FAULT_HWPOISON to -EFAULT, unless FOLL_HWPOISON is set (-> -EHWPOISON) > > ? Or doesn't that happen as you describe "But memory_failure() may fail, and the process's related pte may not be correctly set invalid" -- but why does that happen? On a similar thought, should get_user_pages() never return a page that has HWPoison set? E.g., check also for existing PTEs if the page is hwpoisoned? @Naoya, Oscar -- Thanks, David / dhildenb