Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9E87C6FD19 for ; Mon, 13 Mar 2023 10:38:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230098AbjCMKiG (ORCPT ); Mon, 13 Mar 2023 06:38:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47352 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229888AbjCMKh4 (ORCPT ); Mon, 13 Mar 2023 06:37:56 -0400 Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 021B65F532 for ; Mon, 13 Mar 2023 03:37:30 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R391e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046059;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0VdlJ.M3_1678703847; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VdlJ.M3_1678703847) by smtp.aliyun-inc.com; Mon, 13 Mar 2023 18:37:27 +0800 From: Baolin Wang To: akpm@linux-foundation.org Cc: mgorman@techsingularity.net, osalvador@suse.de, vbabka@suse.cz, william.lam@bytedance.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/2] mm: compaction: fix the possible deadlock when isolating hugetlb pages Date: Mon, 13 Mar 2023 18:37:17 +0800 Message-Id: X-Mailer: git-send-email 2.27.0 In-Reply-To: <1bc1c955b03603c4e14f56dfbbef9f637f18dbbd.1678703534.git.baolin.wang@linux.alibaba.com> References: <1bc1c955b03603c4e14f56dfbbef9f637f18dbbd.1678703534.git.baolin.wang@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When trying to isolate a migratable pageblock, it can contain several normal pages or several hugetlb pages (e.g. CONT-PTE 64K hugetlb on arm64) in a pageblock. That means we may hold the lru lock of a normal page to continue to isolate the next hugetlb page by isolate_or_dissolve_huge_page() in the same migratable pageblock. However in the isolate_or_dissolve_huge_page(), it may allocate a new hugetlb page and dissolve the old one by alloc_and_dissolve_hugetlb_folio() if the hugetlb's refcount is zero. That means we can still enter the direct compaction path to allocate a new hugetlb page under the current lru lock, which may cause possible deadlock. To avoid this possible deadlock, we should release the lru lock when trying to isolate a hugetbl page. Moreover it does not make sense to take the lru lock to isolate a hugetlb, which is not in the lru list. Fixes: 369fa227c219 ("mm: make alloc_contig_range handle free hugetlb pages") Signed-off-by: Baolin Wang --- mm/compaction.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/compaction.c b/mm/compaction.c index c9d9ad958e2a..ac8ff152421a 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -893,6 +893,11 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, } if (PageHuge(page) && cc->alloc_contig) { + if (locked) { + unlock_page_lruvec_irqrestore(locked, flags); + locked = NULL; + } + ret = isolate_or_dissolve_huge_page(page, &cc->migratepages); /* -- 2.27.0