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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C1193C433E0 for ; Mon, 8 Feb 2021 11:06:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7454664E27 for ; Mon, 8 Feb 2021 11:06:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232721AbhBHLFm (ORCPT ); Mon, 8 Feb 2021 06:05:42 -0500 Received: from wforward2-smtp.messagingengine.com ([64.147.123.31]:45525 "EHLO wforward2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232781AbhBHLDU (ORCPT ); Mon, 8 Feb 2021 06:03:20 -0500 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailforward.west.internal (Postfix) with ESMTP id 6E6EAA5D; Mon, 8 Feb 2021 06:01:20 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute4.internal (MEProxy); Mon, 08 Feb 2021 06:01:21 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=GR9QLv uIxByDFRU/eL/OHYlkUqml5Fdr6br8viIQHW8=; b=GUchkr6pRqnfjRapqncTAb /JjBeeJX7yISdlALCBiS8I1TtNkHaHndHeFsz3e5lLtrcg4QL23Wso7LDHpy2yCy cQnZc7iLLqSyzLbOY/uQHJIvL9lzLrN7FinIaoIPkilv3YbmkAex0YPuSpa3j4h3 AisIES1j4DZ71MoV4jqHiMjh+tPBjKvvfo57ZLRDYscWSS8BxhnofH/WhMjAwznb C85N/+h6Eqtv1tYNwKZmdzscImJNohBnHq3gwkKDDTFR3pbOrsVtRaqLdIA773yC 1aNUEkitmFMQQw4/HF+FgxBbCk5Nhv0hUSxOqwhWeCBaU7mTBbZAA3jpZtflKzQQ == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrheefgddvudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecunecujfgurhepuffvhfffkfggtgfgsehtkeertddttd flnecuhfhrohhmpeeoghhrvghgkhhhsehlihhnuhigfhhouhhnuggrthhiohhnrdhorhhg qeenucggtffrrghtthgvrhhnpeelleelvdegfeelledtteegudegfffghfduffduudekge efleegieegkeejhfelveenucffohhmrghinhepkhgvrhhnvghlrdhorhhgnecukfhppeek fedrkeeirdejgedrieegnecuvehluhhsthgvrhfuihiivgepudenucfrrghrrghmpehmrg hilhhfrhhomhepghhrvghgsehkrhhorghhrdgtohhm X-ME-Proxy: Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) by mail.messagingengine.com (Postfix) with ESMTPA id 999C024005A; Mon, 8 Feb 2021 06:01:19 -0500 (EST) Subject: FAILED: patch "[PATCH] mm: hugetlb: fix a race between freeing and dissolving the" failed to apply to 4.9-stable tree To: songmuchun@bytedance.com, akpm@linux-foundation.org, david@redhat.com, mhocko@suse.com, mike.kravetz@oracle.com, osalvador@suse.de, shy828301@gmail.com, stable@vger.kernel.org, torvalds@linux-foundation.org Cc: From: Date: Mon, 08 Feb 2021 12:01:09 +0100 Message-ID: <161278206919633@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 7ffddd499ba6122b1a07828f023d1d67629aa017 Mon Sep 17 00:00:00 2001 From: Muchun Song Date: Thu, 4 Feb 2021 18:32:06 -0800 Subject: [PATCH] mm: hugetlb: fix a race between freeing and dissolving the page 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 window 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. As a result __free_huge_page would corrupt page(s) already in the buddy allocator. Link: https://lkml.kernel.org/r/20210115124942.46403-4-songmuchun@bytedance.com Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage") Signed-off-by: Muchun Song Reviewed-by: Mike Kravetz Reviewed-by: Oscar Salvador Acked-by: Michal Hocko Cc: David Hildenbrand Cc: Yang Shi Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6f0e242d38ca..c6ee3c28a04e 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; @@ -1505,6 +1522,7 @@ 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); } @@ -1755,6 +1773,7 @@ int dissolve_free_huge_page(struct page *page) { int rc = -EBUSY; +retry: /* Not to disrupt normal path by vainly holding hugetlb_lock */ if (!PageHuge(page)) return 0; @@ -1771,6 +1790,26 @@ 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))) { + spin_unlock(&hugetlb_lock); + cond_resched(); + + /* + * Theoretically, we should return -EBUSY when we + * encounter this race. In fact, we have a chance + * to successfully dissolve the page if we do a + * retry. Because the race window is quite small. + * If we seize this opportunity, it is an optimization + * for increasing the success rate of dissolving page. + */ + goto retry; + } + /* * Move PageHWPoison flag from head page to the raw error page, * which makes any subpages rather than the error page reusable.