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Sat, 28 Jun 2025 10:38:20 +0800 Message-ID: Date: Sat, 28 Jun 2025 10:38:20 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v2 1/2] mm/vmscan: fix hwpoisoned large folio handling in shrink_folio_list To: Andrew Morton CC: , , , , , References: <20250627125747.3094074-1-tujinjiang@huawei.com> <20250627125747.3094074-2-tujinjiang@huawei.com> <20250627150007.35d934da6a7a9e3e66488bdd@linux-foundation.org> From: Jinjiang Tu In-Reply-To: <20250627150007.35d934da6a7a9e3e66488bdd@linux-foundation.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.179.13] X-ClientProxiedBy: kwepems500001.china.huawei.com (7.221.188.70) To kwepemo200002.china.huawei.com (7.202.195.209) X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 0A43CA000E X-Stat-Signature: eeoypzwxu84czcu55iokgfczkiy9tadi X-Rspam-User: X-HE-Tag: 1751078305-546303 X-HE-Meta: U2FsdGVkX18weYRiURAQmffhPdJTAkf1/62+3yBuJLzJAQfAr3GDLHxMV/s9mooVJFRrofAXKwrYsu/BpiS2XDpabg9WVpa0nAwcS6jPXBilagqrSR5Swl7WP6ZeT+CCF5zTDtjOfjYoefJkFPH3tviaq8B9oOd5rmo+2dtNuaBArknXqwIE+09tQXRJIhB+JuNBzSLPvL/Tl3YsfgopFGKtWwll7RUvqaSas4LMNGy5JY9prcXJ4rA9XAfuBlFcFswwaxgeNa4PWIxpX9rT+or7KQDEBF5S0bYlArbaxLx9uc3CNNpNs2wtUNOtff/fXOsn/WoxrpW8WiR4v9NQFehqEAa/PDFPQEX/DSQHRS5jbuywm4k8J9pS68IHPGSLDpip5Vlhj+cXeWSlFnwJTEdO+6LoriDTyqxWWckoJ5dBdkA6Z6E24/1TZvWG8TcXjagUSPRWRBtUZ8M/aqG64xqn4B3kmWLSM9k42X/OiwRGEDkiJLJQfOAev7uFCYgUeTPi4QafNdFqO7wDz/I/tLqW4pNsxWGEiCMWSVIie+oxROLJ3OBdM/K5RWB89TdWEik8frMieDBSu/uSb3/bJ2F50rQkvdDGoLgSKb6HXZqSsjs8M0kGgJFEznDF7ojfvpXAATW0/F5aIbt7PkST8wxQUuxvyLcktNhqBzZxFOiZmKU0zQWwPWroVYaqsP6QdGYGhEGsBqIWM/FKSvzCOYEW45QIThC6agIsR0qtPiyZNRUtKRJrTRYnhFQounC8+7hebnKq0G3gV57UWcLAQrjMrEY+Kopxn7JswLkMKlxKZHuJLYt92lPpC5cZXr/95aasa4b36zhp+9oi8yZMZjQn3UJVUqOy9iW6eiRVsF7GSgyoqgh7y/rah2JUogRZ6OP3/rvSQ3QFvopbd8HHo8Ww+3fH+Bpsv2At2t+grmNnG4+c41UFxLx9MMe4hcsOgNfzEM2rsvzm2zbGH5Y wqt8y9wK 59Lqb+4A7pJwEu+aYG7cFBuZJ6ilwyl9NV50jZ9wIfrMl4Q8C76lIEJM2wbVZ0RaE9XeTqHbRP7LAnlSBqdcw8XSgN8Di6ir3a5Tx9lpjEpsSP9BxS7nt5BZ0U8o1jw2AYbG1FmLULzIB96+SVdMw8kc1dygU9I0ClZPDnGUN2H9594fsK103rkixzhlFZVrK9hnEnK+mN/d8OTWX35T7haos+uQTD4t9K+PfSEaMhM5/rMqQc8hrk+6EmHuR2VnAQB3j12s2hpmra/o= 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: 在 2025/6/28 6:00, Andrew Morton 写道: > On Fri, 27 Jun 2025 20:57:46 +0800 Jinjiang Tu wrote: > >> In shrink_folio_list(), the hwpoisoned folio may be large folio, which >> can't be handled by unmap_poisoned_folio(). >> >> Since UCE is rare in real world, and race with reclaimation is more rare, >> just skipping the hwpoisoned large folio is enough. memory_failure() will >> handle it if the UCE is triggered again. >> >> Fixes: 1b0449544c64 ("mm/vmscan: don't try to reclaim hwpoison folio") > Thanks. Can you please fully describe the userspace-visible effects of > this bug? This happens when memory reclaimation for large folio races with memory_failure(), and will lead to kernel panic. The race is as following: cpu0            cpu1  shrink_folio_list memory_failure                       TestSetPageHWPoison     unmap_poisoned_folio      --> trigger BUG_ON due to            unmap_poisoned_folio couldn't            handle large folio > Depending on that information, do you recommend that this fix be > backported into -stable kernels? The fixed commit 1b0449544c64 has been backported to -stable, so this fix should be backported too. > >