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=-10.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 277EAC4727C for ; Fri, 25 Sep 2020 12:56:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DCE252075E for ; Fri, 25 Sep 2020 12:56:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601038567; bh=ijm+fS2MNLDNyGJf/n1YBkhk3QwMXeiOI52TRRaygOs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=O0jBmQLD/kN9ho2a306VkizOAM7ee/999i528AvtOneN1wQr5vHTyTvOdoJzopAEa PtLhPUrX15qBPm0fS9/ZOkdvsfFfBn/SHDABkycepKDnDshjURr1gxW4X2aZBOV9AN CLk5t4Ed6qzIeR9A5RUUIY9eVWPdvTsh60AbaBug= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729475AbgIYM4F (ORCPT ); Fri, 25 Sep 2020 08:56:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:59486 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729460AbgIYMxm (ORCPT ); Fri, 25 Sep 2020 08:53:42 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3DEFF2072E; Fri, 25 Sep 2020 12:53:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601038420; bh=ijm+fS2MNLDNyGJf/n1YBkhk3QwMXeiOI52TRRaygOs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z+wUp9Mvo5wySBu1h88IZ7WFKbBrXBSTI91ExL8RQHb3wZQ23W20eM/n7fal2tWAd 2d3fp9pZx7KtSed/SBtc1nTKqViCZT7qC137kIEtgX8L9l8qwPFCY5YHMEcwiU8dyd Is5wwfwsM+sIr4UhxfUdz0HZJB9f7mr2RJ9bzz64= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ralph Campbell , Andrew Morton , Yang Shi , Zi Yan , Jerome Glisse , John Hubbard , Alistair Popple , Christoph Hellwig , Jason Gunthorpe , Bharata B Rao , Ben Skeggs , Shuah Khan , Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 04/37] mm/thp: fix __split_huge_pmd_locked() for migration PMD Date: Fri, 25 Sep 2020 14:48:32 +0200 Message-Id: <20200925124721.618613840@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200925124720.972208530@linuxfoundation.org> References: <20200925124720.972208530@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ralph Campbell [ Upstream commit ec0abae6dcdf7ef88607c869bf35a4b63ce1b370 ] 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 Signed-off-by: Sasha Levin --- mm/huge_memory.c | 40 +++++++++++++++++++++++----------------- 1 file changed, 23 insertions(+), 17 deletions(-) --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2145,7 +2145,7 @@ static void __split_huge_pmd_locked(stru put_page(page); add_mm_counter(mm, mm_counter_file(page), -HPAGE_PMD_NR); return; - } else if (is_huge_zero_pmd(*pmd)) { + } else if (pmd_trans_huge(*pmd) && is_huge_zero_pmd(*pmd)) { /* * FIXME: Do we want to invalidate secondary mmu by calling * mmu_notifier_invalidate_range() see comments below inside @@ -2233,27 +2233,33 @@ static void __split_huge_pmd_locked(stru 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); + } + + lock_page_memcg(page); + if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { + /* Last compound_mapcount is gone. */ + __dec_lruvec_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); + } } + unlock_page_memcg(page); } smp_wmb(); /* make pte visible before pmd */