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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2D10C43334 for ; Wed, 15 Jun 2022 17:30:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357241AbiFORaA (ORCPT ); Wed, 15 Jun 2022 13:30:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242396AbiFOR3i (ORCPT ); Wed, 15 Jun 2022 13:29:38 -0400 Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 27A8E34BB3 for ; Wed, 15 Jun 2022 10:29:38 -0700 (PDT) Received: by mail-pj1-x1029.google.com with SMTP id k5-20020a17090a404500b001e8875e6242so2670938pjg.5 for ; Wed, 15 Jun 2022 10:29:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=WrF836BhqYoAAQYNFMJen23eOl+F6zz51fEhzRe3ck4=; b=jNiMa1EClCZmNoxHFwK9zkQt71WNj8eQXx1AtJzkARohOhJSxbNe9g9wKpdtMdMiFM JUylBaxwrEsHZe9FDtW/ty8pZHqkoiXrCVnIf4XeVJdT7glhN+11Co4GX3RF1sUTcydf V3HfSNZro9f+AcdFfuHK+L4B6g8H28LVBK/7P7o1JiWQR01uO+wBiMM/9HiCPM6SAMQx d2a2Sz0T524tVIKdzfkdECmzkPJH8aXQXrXRWCyPKVJHg489kISeCmxjam/lwp9uY3TL eupQy8+iv/QTL3N+W5Rklt4NRIJ/YA5TCnZRDnOfKJw5G4UK28mGTOs/faVfewTqkG2c Oztw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=WrF836BhqYoAAQYNFMJen23eOl+F6zz51fEhzRe3ck4=; b=6GYxj8c4efxyDZuscsY6CuorXXB84ETMOEBLdVV1kEfn5THX4LIApMSmxSldSNHzCL jcDl5nRr7TtdklXetfpymE9/Q8hTBz3/Wj6/FoBI2asWQCRpgVQyJc8Naa6jbnfyQ6q6 S6VYnJkRkciARry/XywJCwX+ZA0YPSGguv6XRPwm/24zKwUwbzP9AR+oSbT+tpZMr7lo YwNJXVZbhqxqxPKhCjOttyEScMvqJnFJ99z5bHduf147yh7JcGZrwuYZnWoXh7V4vRic 09o71ybsIq4PwuYHyt6RVDOgkCZWAR3DQMZsbt/fZpiyYepFes8+Nek3fZ7dwhrrDLWX udCg== X-Gm-Message-State: AJIora8EZIxG179JGHE+y54cQzOYOGZZU7sdFmx8xeRM5pqQho6YwGRW ItLWJHvCGzUjaaXeq9E99Z8= X-Google-Smtp-Source: AGRyM1vRDq5qAc7St9qdLuZS57haehWUHZEdEiVLV8l2rTbRMydreLZ77f4O354sxk37OOZMcG9tJw== X-Received: by 2002:a17:90b:4c4c:b0:1e8:6f9a:b642 with SMTP id np12-20020a17090b4c4c00b001e86f9ab642mr11434299pjb.21.1655314177666; Wed, 15 Jun 2022 10:29:37 -0700 (PDT) Received: from localhost.localdomain (c-67-174-241-145.hsd1.ca.comcast.net. [67.174.241.145]) by smtp.gmail.com with ESMTPSA id w14-20020a1709029a8e00b001676f87473fsm9552244plp.302.2022.06.15.10.29.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jun 2022 10:29:37 -0700 (PDT) From: Yang Shi To: vbabka@suse.cz, kirill.shutemov@linux.intel.com, willy@infradead.org, zokeefe@google.com, linmiaohe@huawei.com, akpm@linux-foundation.org Cc: shy828301@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [v4 PATCH 3/7] mm: khugepaged: better comments for anon vma check in hugepage_vma_revalidate Date: Wed, 15 Jun 2022 10:29:22 -0700 Message-Id: <20220615172926.546974-4-shy828301@gmail.com> X-Mailer: git-send-email 2.26.3 In-Reply-To: <20220615172926.546974-1-shy828301@gmail.com> References: <20220615172926.546974-1-shy828301@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The hugepage_vma_revalidate() needs to check if the vma is still anonymous vma or not since the address may be unmapped then remapped to file before khugepaged reaquired the mmap_lock. The old comment is not quite helpful, elaborate this with better comment. Signed-off-by: Yang Shi --- mm/khugepaged.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index db0b334a7d1f..5baa394e34c8 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -960,7 +960,13 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, return SCAN_ADDRESS_RANGE; if (!hugepage_vma_check(vma, vma->vm_flags)) return SCAN_VMA_CHECK; - /* Anon VMA expected */ + /* + * Anon VMA expected, the address may be unmapped then + * remapped to file after khugepaged reaquired the mmap_lock. + * + * hugepage_vma_check may return true for qualified file + * vmas. + */ if (!vma->anon_vma || !vma_is_anonymous(vma)) return SCAN_VMA_CHECK; return 0; -- 2.26.3