From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9AFD9C48BDF for ; Wed, 16 Jun 2021 01:23:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 4930C61159 for ; Wed, 16 Jun 2021 01:23:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4930C61159 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E13F96B006E; Tue, 15 Jun 2021 21:23:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DC37A6B0070; Tue, 15 Jun 2021 21:23:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C3D936B0071; Tue, 15 Jun 2021 21:23:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0138.hostedemail.com [216.40.44.138]) by kanga.kvack.org (Postfix) with ESMTP id 8E48F6B006E for ; Tue, 15 Jun 2021 21:23:15 -0400 (EDT) Received: from smtpin40.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 21091180AD806 for ; Wed, 16 Jun 2021 01:23:15 +0000 (UTC) X-FDA: 78257838750.40.1CF3066 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf24.hostedemail.com (Postfix) with ESMTP id DCFDEA00014E for ; Wed, 16 Jun 2021 01:23:04 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 9967161356; Wed, 16 Jun 2021 01:23:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1623806593; bh=rHRSsmAz4Uacfxb5kv+BqE8Wo9Zjx9aIfdgIONWU1Ik=; h=Date:From:To:Subject:In-Reply-To:From; b=Ok83/KO1DN1KISf3IdQFiu2ZhVujKe5PNr6nZZmz/1eJ+Ml/zMhMF2zSFyLaogOWA kVa++kAqst7Se+YUlvUIPii+wvJzaMaK+ZZFQdThILSL4pCnVZ7ZFMDUxcRLxtQMcj M5cIQLR2Qv8UprUpSn+d51+139s/oJ8YZBECXR1A= Date: Tue, 15 Jun 2021 18:23:13 -0700 From: Andrew Morton To: akpm@linux-foundation.org, linux-mm@kvack.org, mhocko@suse.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, naoya.horiguchi@nec.com, osalvador@suse.de, songmuchun@bytedance.com, stable@vger.kernel.org, tony.luck@intel.com, torvalds@linux-foundation.org Subject: [patch 01/18] mm,hwpoison: fix race with hugetlb page allocation Message-ID: <20210616012313.cySUhIHf_%akpm@linux-foundation.org> In-Reply-To: <20210615182248.9a0ba90e8e66b9f4a53c0d23@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b="Ok83/KO1"; dmarc=none; spf=pass (imf24.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspamd-Server: rspam02 X-Stat-Signature: dggpmepwd688acbntwmf65jwkcawfwpq X-Rspamd-Queue-Id: DCFDEA00014E X-HE-Tag: 1623806584-399453 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: From: Naoya Horiguchi Subject: mm,hwpoison: fix race with hugetlb page allocation 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 not enough because there's a time window where compound pages have non-zero refcount during hugetlb page initialization. So make __get_hwpoison_page() check page status a bit more for hugetlb pages with get_hwpoison_huge_page(). Checking hugetlb-specific flags under hugetlb_lock makes sure that the hugetlb page is not transitive. It's notable that another new function, HWPoisonHandlable(), is helpful to prevent a race against other transitive page states (like a generic compound page just before PageHuge becomes true). Link: https://lkml.kernel.org/r/20210603233632.2964832-2-nao.horiguchi@gmail.com Fixes: ead07f6a867b ("mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling") Signed-off-by: Naoya Horiguchi Reported-by: Muchun Song Acked-by: Mike Kravetz Cc: Oscar Salvador Cc: Michal Hocko Cc: Tony Luck Cc: [5.12+] Signed-off-by: Andrew Morton --- include/linux/hugetlb.h | 6 ++++++ mm/hugetlb.c | 15 +++++++++++++++ mm/memory-failure.c | 29 +++++++++++++++++++++++++++-- 3 files changed, 48 insertions(+), 2 deletions(-) --- a/include/linux/hugetlb.h~mmhwpoison-fix-race-with-hugetlb-page-allocation +++ a/include/linux/hugetlb.h @@ -149,6 +149,7 @@ bool hugetlb_reserve_pages(struct inode 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(str 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) { } --- a/mm/hugetlb.c~mmhwpoison-fix-race-with-hugetlb-page-allocation +++ a/mm/hugetlb.c @@ -5857,6 +5857,21 @@ unlock: 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); --- a/mm/memory-failure.c~mmhwpoison-fix-race-with-hugetlb-page-allocation +++ a/mm/memory-failure.c @@ -949,6 +949,17 @@ static int page_action(struct page_state return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY; } +/* + * Return true if a page type of a given page is supported by hwpoison + * mechanism (while handling could fail), otherwise false. This function + * does not return true for hugetlb or device memory pages, so it's assumed + * to be called only in the context where we never have such pages. + */ +static inline bool HWPoisonHandlable(struct page *page) +{ + return PageLRU(page) || __PageMovable(page); +} + /** * __get_hwpoison_page() - Get refcount for memory error handling: * @page: raw error page (hit by memory error) @@ -959,8 +970,22 @@ static int page_action(struct page_state 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; + + /* + * This check prevents from calling get_hwpoison_unless_zero() + * for any unsupported type of page in order to reduce the risk of + * unexpected races caused by taking a page refcount. + */ + if (!HWPoisonHandlable(head)) + return 0; - 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. @@ -1017,7 +1042,7 @@ try_again: ret = -EIO; } } else { - if (PageHuge(p) || PageLRU(p) || __PageMovable(p)) { + if (PageHuge(p) || HWPoisonHandlable(p)) { ret = 1; } else { /* _