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Tue, 12 Aug 2025 10:01:02 +0800 Received: from [10.173.125.236] (10.173.125.236) by kwepemq500010.china.huawei.com (7.202.194.235) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 12 Aug 2025 10:01:01 +0800 Subject: Re: [PATCH v2] mm/memory-failure: fix infinite UCE for VM_PFNMAP'ed page To: Jinjiang Tu CC: , , , , , , , References: <20250811043323.899130-1-tujinjiang@huawei.com> From: Miaohe Lin Message-ID: Date: Tue, 12 Aug 2025 10:01:01 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20250811043323.899130-1-tujinjiang@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.125.236] X-ClientProxiedBy: kwepems100001.china.huawei.com (7.221.188.238) To kwepemq500010.china.huawei.com (7.202.194.235) X-Rspamd-Queue-Id: 444931A0007 X-Stat-Signature: tay1ndswwk6eob3ks3jksewt5tqgesqc X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1754964065-791575 X-HE-Meta: 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 pFyu6mER DKr3U3kaw8f6sMGUkgOxG87dIqbBTaGPfMp8tqqS505eP5mA9wHhMddsvMNyBmB/suzBdJ/HCHSgOR5L9YIApsBySaeGbD16xRDvQhA7CHMF6BeuiG7SwmiEDiHPdy+kTYan/DP1peYfWWAI4hGTz8o2PMKQ3jN59RM7wvjw+/4QTfIkjRUVtyfQ+jahcCA9L0h7rlKwH57LB789scsy/iXDVaXIWcve5A+RdNZZayHz8ynwfdISN4P0pDoLL/KOVFpfFwpqg9qaVN2A97tFlM36zD9AzubGUK/vtRyWtzsOI3Ev+Ps7AEE+f23cz2n1S2QA6 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: List-Subscribe: List-Unsubscribe: On 2025/8/11 12:33, Jinjiang Tu wrote: > When memory_failure() is called for a already hwpoisoned pfn backed with > struct page, kill_accessing_process() will conditionally send a SIGBUS to > the current (triggering) process if it maps the page. > > However, in case the page is not ordinarily mapped, but was mapped through > remap_pfn_range(), kill_accessing_process() wouldn't identify it as mapped > even though hwpoison_pte_range() would be prepared to handle it, because > walk_page_range() will skip VM_PFNMAP as default in walk_page_test(). As > a result, walk_page_range() will return 0, assuming "not mapped" and SIGBUS > will be skipped. The user task will trigger UCE infinitely because it will > not receive a SIGBUS on access and simply retry. > > Before commit aaf99ac2ceb7 ("mm/hwpoison: do not send SIGBUS to processes > with recovered clean pages"), kill_accessing_process() will return EFAULT. > For x86, the current task will be killed in kill_me_maybe(). > > To fix it, add .test_walk callback for hwpoison_walk_ops to process > VM_PFNMAP VMAs too. > > Fixes: aaf99ac2ceb7 ("mm/hwpoison: do not send SIGBUS to processes with recovered clean pages") > Signed-off-by: Jinjiang Tu > --- > Changelog since v1: > * update patch description, suggested by David Hildenbrand > > mm/memory-failure.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index e2e685b971bb..fa6a8f2cdebc 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -853,9 +853,16 @@ static int hwpoison_hugetlb_range(pte_t *ptep, unsigned long hmask, > #define hwpoison_hugetlb_range NULL > #endif > It might be better to add a comment on why below hwpoison_test_walk is needed. It looks somewhat weird as hwpoison_test_walk simply return 0. > +static int hwpoison_test_walk(unsigned long start, unsigned long end, > + struct mm_walk *walk) > +{ > + return 0; > +} > + Anyway, this patch looks good to me. Acked-by: Miaohe Lin Thanks. .