From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C13DF6453 for ; Tue, 22 Mar 2022 21:44:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87E5CC340EC; Tue, 22 Mar 2022 21:44:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1647985485; bh=xkrxMmxe6pG21FSJF2rhuxx4y2yhqicxMLIqE2ZKoBE=; h=Date:To:From:In-Reply-To:Subject:From; b=rB3psBfOiPS3FnNak3XUxZ8Sx/pbZJonkV5mmXdkFvPuDN5kft/JrWytK14FMpdEn in/TWE11XTuDSOljQ7j/xXBnGnOP90Ma4Pq9D2bvPu8NttYKHb2Cxfcc583+DaKqOr Q7XeLQNbaxlR3M6XRyngY8ujzkaPAcV/x3KjtG9M= Date: Tue, 22 Mar 2022 14:44:44 -0700 To: tony.luck@intel.com,shy828301@gmail.com,naoya.horiguchi@nec.com,mike.kravetz@oracle.com,bp@alien8.de,linmiaohe@huawei.com,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220322143803.04a5e59a07e48284f196a2f9@linux-foundation.org> Subject: [patch 123/227] mm/memory-failure.c: fix race with changing page compound again Message-Id: <20220322214445.87E5CC340EC@smtp.kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Miaohe Lin Subject: mm/memory-failure.c: fix race with changing page compound again Patch series "A few fixup patches for memory failure", v2. This series contains a few patches to fix the race with changing page compound page, make non-LRU movable pages unhandlable and so on. More details can be found in the respective changelogs. There is a race window where we got the compound_head, the hugetlb page could be freed to buddy, or even changed to another compound page just before we try to get hwpoison page. Think about the below race window: CPU 1 CPU 2 memory_failure_hugetlb struct page *head = compound_head(p); hugetlb page might be freed to buddy, or even changed to another compound page. get_hwpoison_page -- page is not what we want now... If this race happens, just bail out. Also MF_MSG_DIFFERENT_PAGE_SIZE is introduced to record this event. [akpm@linux-foundation.org: s@/**@/*@, per Naoya Horiguchi] Link: https://lkml.kernel.org/r/20220312074613.4798-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20220312074613.4798-2-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Acked-by: Naoya Horiguchi Cc: Tony Luck Cc: Borislav Petkov Cc: Mike Kravetz Cc: Yang Shi Signed-off-by: Andrew Morton --- include/linux/mm.h | 1 + include/ras/ras_event.h | 1 + mm/memory-failure.c | 12 ++++++++++++ 3 files changed, 14 insertions(+) --- a/include/linux/mm.h~mm-memory-failurec-fix-race-with-changing-page-compound-again +++ a/include/linux/mm.h @@ -3239,6 +3239,7 @@ enum mf_action_page_type { MF_MSG_BUDDY, MF_MSG_DAX, MF_MSG_UNSPLIT_THP, + MF_MSG_DIFFERENT_PAGE_SIZE, MF_MSG_UNKNOWN, }; --- a/include/ras/ras_event.h~mm-memory-failurec-fix-race-with-changing-page-compound-again +++ a/include/ras/ras_event.h @@ -374,6 +374,7 @@ TRACE_EVENT(aer_event, EM ( MF_MSG_BUDDY, "free buddy page" ) \ EM ( MF_MSG_DAX, "dax page" ) \ EM ( MF_MSG_UNSPLIT_THP, "unsplit thp" ) \ + EM ( MF_MSG_DIFFERENT_PAGE_SIZE, "different page size" ) \ EMe ( MF_MSG_UNKNOWN, "unknown page" ) /* --- a/mm/memory-failure.c~mm-memory-failurec-fix-race-with-changing-page-compound-again +++ a/mm/memory-failure.c @@ -732,6 +732,7 @@ static const char * const action_page_ty [MF_MSG_BUDDY] = "free buddy page", [MF_MSG_DAX] = "dax page", [MF_MSG_UNSPLIT_THP] = "unsplit thp", + [MF_MSG_DIFFERENT_PAGE_SIZE] = "different page size", [MF_MSG_UNKNOWN] = "unknown page", }; @@ -1532,6 +1533,17 @@ static int memory_failure_hugetlb(unsign } lock_page(head); + + /* + * The page could have changed compound pages due to race window. + * If this happens just bail out. + */ + if (!PageHuge(p) || compound_head(p) != head) { + action_result(pfn, MF_MSG_DIFFERENT_PAGE_SIZE, MF_IGNORED); + res = -EBUSY; + goto out; + } + page_flags = head->flags; if (hwpoison_filter(p)) { _