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[175.177.40.153]) by smtp.gmail.com with ESMTPSA id f14sm14437473pjq.50.2021.05.18.16.13.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 May 2021 16:13:12 -0700 (PDT) From: Naoya Horiguchi To: Oscar Salvador , Muchun Song , linux-mm@kvack.org Cc: Andrew Morton , Mike Kravetz , Michal Hocko , Tony Luck , Naoya Horiguchi , linux-kernel@vger.kernel.org Subject: [PATCH v5 1/2] mm,hwpoison: fix race with hugetlb page allocation Date: Wed, 19 May 2021 08:12:58 +0900 Message-Id: <20210518231259.2553203-2-nao.horiguchi@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210518231259.2553203-1-nao.horiguchi@gmail.com> References: <20210518231259.2553203-1-nao.horiguchi@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Naoya Horiguchi When hugetlb page fault (under overcommitting situation) and memory_failure() race, VM_BUG_ON_PAGE() is triggered by the following race: CPU0: CPU1: gather_surplus_pages() page = alloc_surplus_huge_page() memory_failure_hugetlb() get_hwpoison_page(page) __get_hwpoison_page(page) get_page_unless_zero(page) zero = put_page_testzero(page) VM_BUG_ON_PAGE(!zero, page) enqueue_huge_page(h, page) put_page(page) __get_hwpoison_page() only checks the page refcount before taking an additional one for memory error handling, which is wrong because there's a time window where compound pages have non-zero refcount during initialization. So make __get_hwpoison_page() check page status a bit more for hugetlb pages. Fixes: ead07f6a867b ("mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling") Signed-off-by: Naoya Horiguchi Reported-by: Muchun Song Cc: stable@vger.kernel.org # 5.12+ --- include/linux/hugetlb.h | 6 ++++++ mm/hugetlb.c | 15 +++++++++++++++ mm/memory-failure.c | 8 +++++++- 3 files changed, 28 insertions(+), 1 deletion(-) diff --git v5.13-rc2/include/linux/hugetlb.h v5.13-rc2_patched/include/linux/hugetlb.h index b92f25ccef58..790ae618548d 100644 --- v5.13-rc2/include/linux/hugetlb.h +++ v5.13-rc2_patched/include/linux/hugetlb.h @@ -149,6 +149,7 @@ bool hugetlb_reserve_pages(struct inode *inode, long from, long to, long hugetlb_unreserve_pages(struct inode *inode, long start, long end, long freed); bool isolate_huge_page(struct page *page, struct list_head *list); +int get_hwpoison_huge_page(struct page *page, bool *hugetlb); void putback_active_hugepage(struct page *page); void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason); void free_huge_page(struct page *page); @@ -339,6 +340,11 @@ static inline bool isolate_huge_page(struct page *page, struct list_head *list) return false; } +static inline int get_hwpoison_huge_page(struct page *page, bool *hugetlb) +{ + return 0; +} + static inline void putback_active_hugepage(struct page *page) { } diff --git v5.13-rc2/mm/hugetlb.c v5.13-rc2_patched/mm/hugetlb.c index 95918f410c0f..f138bae3e302 100644 --- v5.13-rc2/mm/hugetlb.c +++ v5.13-rc2_patched/mm/hugetlb.c @@ -5847,6 +5847,21 @@ bool isolate_huge_page(struct page *page, struct list_head *list) return ret; } +int get_hwpoison_huge_page(struct page *page, bool *hugetlb) +{ + int ret = 0; + + *hugetlb = false; + spin_lock_irq(&hugetlb_lock); + if (PageHeadHuge(page)) { + *hugetlb = true; + if (HPageFreed(page) || HPageMigratable(page)) + ret = get_page_unless_zero(page); + } + spin_unlock_irq(&hugetlb_lock); + return ret; +} + void putback_active_hugepage(struct page *page) { spin_lock_irq(&hugetlb_lock); diff --git v5.13-rc2/mm/memory-failure.c v5.13-rc2_patched/mm/memory-failure.c index 85ad98c00fd9..353c6177e489 100644 --- v5.13-rc2/mm/memory-failure.c +++ v5.13-rc2_patched/mm/memory-failure.c @@ -959,8 +959,14 @@ static int page_action(struct page_state *ps, struct page *p, static int __get_hwpoison_page(struct page *page) { struct page *head = compound_head(page); + int ret = 0; + bool hugetlb = false; + + ret = get_hwpoison_huge_page(head, &hugetlb); + if (hugetlb) + return ret; - if (!PageHuge(head) && PageTransHuge(head)) { + if (PageTransHuge(head)) { /* * Non anonymous thp exists only in allocation/free time. We * can't handle such a case correctly, so let's give it up. -- 2.25.1