From patchwork Mon Sep 21 18:27:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zi Yan X-Patchwork-Id: 309289 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=-12.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 743B5C35257 for ; Mon, 21 Sep 2020 18:36:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 066312311D for ; Mon, 21 Sep 2020 18:36:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=sent.com header.i=@sent.com header.b="Q93p3HxR"; dkim=temperror (0-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="f5OKr/kw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727430AbgIUSgE (ORCPT ); Mon, 21 Sep 2020 14:36:04 -0400 Received: from wnew1-smtp.messagingengine.com ([64.147.123.26]:55449 "EHLO wnew1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727475AbgIUSgE (ORCPT ); Mon, 21 Sep 2020 14:36:04 -0400 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailnew.west.internal (Postfix) with ESMTP id 34F584FB; Mon, 21 Sep 2020 14:27:08 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute4.internal (MEProxy); Mon, 21 Sep 2020 14:27:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sent.com; h=from :to:cc:subject:date:message-id:reply-to:mime-version :content-transfer-encoding; s=fm1; bh=IzZB//QV9JGG+wl/WkCMJlU/R7 ILM8c5yMDxhwndAiE=; b=Q93p3HxRPYJlxODgTKlvWduim8lyTqBOSdtrLqPrv6 KvBRygqXUHkbum6d1OLpK4j6o0Gxv9quD64C9KgZDtVvBCgp7I8LlZdohq8QQ0ru uUaldSqTwn7HnPikNL+yoBMOix5LXVTUpdQe3cQKQ73m4pq0+80SqHSbpnYeg4e8 IIWVphhmuWOr2OGOu7GloYQGDAHxHYMY2gpfSKp+HgwPJWmM8rMpgn4NfpEr+/O1 XoAFqUO54kqXokqsBQWIF/rbpj19Wqmc0wOL0W/KVF7C83Az4ucBhpr8x9zWN+M4 W88VLY18Zd/aTo2ItFB4fiwc4jEBwWNxrsQHQ2Q25pAA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:date:from :message-id:mime-version:reply-to:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=IzZB// QV9JGG+wl/WkCMJlU/R7ILM8c5yMDxhwndAiE=; b=f5OKr/kwuid2APqztPS9ZH f3Sw4930DEo7cDH77vKdc039IjguzdDqGzHTyRqM6c+s9jn69tKY2LFZZ7E27P0N LyZfCibpdNoZfDiLIu+Y3eGEE9zn/L/JKn+TvLVulRHI+bLPmZfvDg4h+f2JqHnc Gs0h+M0WRcP953zeWiDb2mqppKLFbZyWxbYjef6Ppg3fdAxVhRmVG6s9IlF9ra42 DJHWVjhDk55bG0yzC2ly14hLDZddiTAa7xbfHMiahUwXu4XODn7nw6GsANEjvMxe CfK6H5pWpVTpRUG7InyfwM7iHs2FT0J+V5+M5wvoufHQyV5UwR3ZHV05AGLN+ASA == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedujedruddvgdduvdejucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvufffkfforhgggfestdekredtredttdenucfhrhhomhepkghiucgjrghn uceoiihirdihrghnsehsvghnthdrtghomheqnecuggftrfgrthhtvghrnheptedvkedthf fgvedufeeuuedvteevjeejleffkefhgeevgfegieffhfduveeiledtnecuffhomhgrihhn pehkvghrnhgvlhdrohhrghenucfkphepuddvrdegiedruddtiedrudeigeenucevlhhush htvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpeiiihdrhigrnhesshgv nhhtrdgtohhm X-ME-Proxy: Received: from nvrsysarch6.NVidia.COM (unknown [12.46.106.164]) by mail.messagingengine.com (Postfix) with ESMTPA id D2CEA3064610; Mon, 21 Sep 2020 14:27:06 -0400 (EDT) From: Zi Yan To: stable@vger.kernel.org Cc: Zi Yan , Ralph Campbell , Andrew Morton , Yang Shi , Jerome Glisse , John Hubbard , Alistair Popple , Christoph Hellwig , Jason Gunthorpe , Bharata B Rao , Ben Skeggs , Shuah Khan , Linus Torvalds Subject: [PATCH] mm/thp: fix __split_huge_pmd_locked() for migration PMD Date: Mon, 21 Sep 2020 14:27:01 -0400 Message-Id: <20200921182701.2617910-1-zi.yan@sent.com> X-Mailer: git-send-email 2.28.0 Reply-To: Zi Yan MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Zi Yan For 4.14. [Upstream commitid ec0abae6dcdf7ef88607c869bf35a4b63ce1b370] From: Ralph Campbell Date: Fri, 18 Sep 2020 21:20:24 -0700 Subject: [PATCH] mm/thp: fix __split_huge_pmd_locked() for migration PMD A migrating transparent huge page has to already be unmapped. Otherwise, the page could be modified while it is being copied to a new page and data could be lost. The function __split_huge_pmd() checks for a PMD migration entry before calling __split_huge_pmd_locked() leading one to think that __split_huge_pmd_locked() can handle splitting a migrating PMD. However, the code always increments the page->_mapcount and adjusts the memory control group accounting assuming the page is mapped. Also, if the PMD entry is a migration PMD entry, the call to is_huge_zero_pmd(*pmd) is incorrect because it calls pmd_pfn(pmd) instead of migration_entry_to_pfn(pmd_to_swp_entry(pmd)). Fix these problems by checking for a PMD migration entry. Fixes: 84c3fc4e9c56 ("mm: thp: check pmd migration entry in common path") Signed-off-by: Ralph Campbell Signed-off-by: Andrew Morton Reviewed-by: Yang Shi Reviewed-by: Zi Yan Cc: Jerome Glisse Cc: John Hubbard Cc: Alistair Popple Cc: Christoph Hellwig Cc: Jason Gunthorpe Cc: Bharata B Rao Cc: Ben Skeggs Cc: Shuah Khan Cc: [4.14+] Link: https://lkml.kernel.org/r/20200903183140.19055-1-rcampbell@nvidia.com Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 37 ++++++++++++++++++++----------------- 1 file changed, 20 insertions(+), 17 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 9f3d4f84032b..0aeadebb6f79 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2078,7 +2078,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, put_page(page); add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR); return; - } else if (is_huge_zero_pmd(*pmd)) { + } else if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) { return __split_huge_zero_page_pmd(vma, haddr, pmd); } @@ -2131,26 +2131,29 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, pte = pte_offset_map(&_pmd, addr); BUG_ON(!pte_none(*pte)); set_pte_at(mm, addr, pte, entry); - atomic_inc(&page[i]._mapcount); - pte_unmap(pte); - } - - /* - * Set PG_double_map before dropping compound_mapcount to avoid - * false-negative page_mapped(). - */ - if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { - for (i = 0; i < HPAGE_PMD_NR; i++) + if (!pmd_migration) atomic_inc(&page[i]._mapcount); + pte_unmap(pte); } - if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { - /* Last compound_mapcount is gone. */ - __dec_node_page_state(page, NR_ANON_THPS); - if (TestClearPageDoubleMap(page)) { - /* No need in mapcount reference anymore */ + if (!pmd_migration) { + /* + * Set PG_double_map before dropping compound_mapcount to avoid + * false-negative page_mapped(). + */ + if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) { for (i = 0; i < HPAGE_PMD_NR; i++) - atomic_dec(&page[i]._mapcount); + atomic_inc(&page[i]._mapcount); + } + + if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { + /* Last compound_mapcount is gone. */ + __dec_node_page_state(page, NR_ANON_THPS); + if (TestClearPageDoubleMap(page)) { + /* No need in mapcount reference anymore */ + for (i = 0; i < HPAGE_PMD_NR; i++) + atomic_dec(&page[i]._mapcount); + } } }