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=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,URIBL_BLOCKED,USER_AGENT_GIT 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 DFA76C433E6 for ; Wed, 13 Jan 2021 05:26:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 96DD823117 for ; Wed, 13 Jan 2021 05:26:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726251AbhAMF0e (ORCPT ); Wed, 13 Jan 2021 00:26:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33252 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726202AbhAMF0d (ORCPT ); Wed, 13 Jan 2021 00:26:33 -0500 Received: from mail-pg1-x534.google.com (mail-pg1-x534.google.com [IPv6:2607:f8b0:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8784BC0617A2 for ; Tue, 12 Jan 2021 21:25:44 -0800 (PST) Received: by mail-pg1-x534.google.com with SMTP id 30so766393pgr.6 for ; Tue, 12 Jan 2021 21:25:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=JlQZQVrOm402ulHFjYHU+1nImQj/z6C/J2SHh6gZPrk=; b=ujayAIQH7e5D07vHiW8ktnM5b+1Sj0HSbBPecs9gbudPs6Gv3oWDdnyOFdH38A5eoV EvMMnU9FgwoYk1vghm+TAafxj45NdEG7v65EG2XTFOjwtTS0fqGmuBykLlZaXAmKluNq gLMMRGSswPNoNA1IdD7Pv/aImOdpFtgTu3s3qFXKokNIhsjDi1M9+a3FpM5na3PC32MA OWVoLNsEucG1t72DMPtUPB0B3iB6gVheQ9RDr5qs6UtF9qCNLDoq+76i+JTJfpYh+b4l /3B0SQyesOGSFdCS6lThNm4lVo+G8umqvRHU8MfQtA/ZlQg4tSBHd1CJyL9K5o9IqtQN zECg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=JlQZQVrOm402ulHFjYHU+1nImQj/z6C/J2SHh6gZPrk=; b=G3byfOGUmCYlPnG7fcM7w9IIbUr6JaZLyX5WS51KSAUOLIQ7mYvqJ94j0XLn0O5a3m 4h80EjFlHmQL8WSLfTlz9nyXNZRLSqK9SoWyPHTUo70jsWWXgGECYHceAltd0ubtv+kj gJp30MToJIjJrZAsKvG1Ehon8oR5D77yHXUTncJeAqcY5htaBJ0tI1UZWdaNGS+1OcBG sGxEIh84DrTR5WqWZdywvjIKiCLqx+fOhaFokznrfXkj3uRovI2obvpQ8m5Z1aj9gcjE qhsJBl15uhuhtYzX/67ay27G7NVdm7daZBntUprhM66Old0Qcxia2YPWiYhqR/yaDiEw 8BnQ== X-Gm-Message-State: AOAM5312TiUgGdXp5/UtSvL/A3soCiRATEEpZNV7HkH1fT/eMv+H3nGr aFyAlySyvmu7WUHyfN/W7I1a8w== X-Google-Smtp-Source: ABdhPJxPLRQfjsTnvt/HmlGnGJNCjHsOsPGMcbaQEqmWlQVyc40MLv2lELMjR5jMm2y+VTHq3wbtcQ== X-Received: by 2002:aa7:843a:0:b029:19d:b279:73c9 with SMTP id q26-20020aa7843a0000b029019db27973c9mr447437pfn.3.1610515544150; Tue, 12 Jan 2021 21:25:44 -0800 (PST) Received: from localhost.localdomain ([139.177.225.247]) by smtp.gmail.com with ESMTPSA id x15sm893081pfa.80.2021.01.12.21.25.40 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Jan 2021 21:25:43 -0800 (PST) From: Muchun Song To: mike.kravetz@oracle.com, akpm@linux-foundation.org Cc: n-horiguchi@ah.jp.nec.com, ak@linux.intel.com, mhocko@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Muchun Song , stable@vger.kernel.org Subject: [PATCH v4 3/6] mm: hugetlb: fix a race between freeing and dissolving the page Date: Wed, 13 Jan 2021 13:22:06 +0800 Message-Id: <20210113052209.75531-4-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) In-Reply-To: <20210113052209.75531-1-songmuchun@bytedance.com> References: <20210113052209.75531-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is a race condition between __free_huge_page() and dissolve_free_huge_page(). CPU0: CPU1: // page_count(page) == 1 put_page(page) __free_huge_page(page) dissolve_free_huge_page(page) spin_lock(&hugetlb_lock) // PageHuge(page) && !page_count(page) update_and_free_page(page) // page is freed to the buddy spin_unlock(&hugetlb_lock) spin_lock(&hugetlb_lock) clear_page_huge_active(page) enqueue_huge_page(page) // It is wrong, the page is already freed spin_unlock(&hugetlb_lock) The race windows is between put_page() and dissolve_free_huge_page(). We should make sure that the page is already on the free list when it is dissolved. Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage") Signed-off-by: Muchun Song Reviewed-by: Mike Kravetz Cc: stable@vger.kernel.org --- mm/hugetlb.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 4741d60f8955..4a9011e12175 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -79,6 +79,21 @@ DEFINE_SPINLOCK(hugetlb_lock); static int num_fault_mutexes; struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp; +static inline bool PageHugeFreed(struct page *head) +{ + return page_private(head + 4) == -1UL; +} + +static inline void SetPageHugeFreed(struct page *head) +{ + set_page_private(head + 4, -1UL); +} + +static inline void ClearPageHugeFreed(struct page *head) +{ + set_page_private(head + 4, 0); +} + /* Forward declaration */ static int hugetlb_acct_memory(struct hstate *h, long delta); @@ -1028,6 +1043,7 @@ static void enqueue_huge_page(struct hstate *h, struct page *page) list_move(&page->lru, &h->hugepage_freelists[nid]); h->free_huge_pages++; h->free_huge_pages_node[nid]++; + SetPageHugeFreed(page); } static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid) @@ -1044,6 +1060,7 @@ static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid) list_move(&page->lru, &h->hugepage_activelist); set_page_refcounted(page); + ClearPageHugeFreed(page); h->free_huge_pages--; h->free_huge_pages_node[nid]--; return page; @@ -1504,6 +1521,7 @@ static void prep_new_huge_page(struct hstate *h, struct page *page, int nid) spin_lock(&hugetlb_lock); h->nr_huge_pages++; h->nr_huge_pages_node[nid]++; + ClearPageHugeFreed(page); spin_unlock(&hugetlb_lock); } @@ -1770,6 +1788,14 @@ int dissolve_free_huge_page(struct page *page) int nid = page_to_nid(head); if (h->free_huge_pages - h->resv_huge_pages == 0) goto out; + + /* + * We should make sure that the page is already on the free list + * when it is dissolved. + */ + if (unlikely(!PageHugeFreed(head))) + goto out; + /* * Move PageHWPoison flag from head page to the raw error page, * which makes any subpages rather than the error page reusable. -- 2.11.0