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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D1BFC43217 for ; Wed, 2 Mar 2022 03:21:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F011F8D0002; Tue, 1 Mar 2022 22:21:13 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EB0A18D0001; Tue, 1 Mar 2022 22:21:13 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DA0BE8D0002; Tue, 1 Mar 2022 22:21:13 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0249.hostedemail.com [216.40.44.249]) by kanga.kvack.org (Postfix) with ESMTP id C7C318D0001 for ; Tue, 1 Mar 2022 22:21:13 -0500 (EST) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 8889B181C9BAC for ; Wed, 2 Mar 2022 03:21:13 +0000 (UTC) X-FDA: 79197995226.21.5413BCF Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by imf04.hostedemail.com (Postfix) with ESMTP id 6B6C640003 for ; Wed, 2 Mar 2022 03:21:12 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4K7fR10Lj5z1GC0v; Wed, 2 Mar 2022 11:16:29 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Wed, 2 Mar 2022 11:21:07 +0800 Subject: Re: [PATCH 3/8] mm: khugepaged: skip DAX vma To: Yang Shi CC: , , , , , , , , , , , , , , References: <20220228235741.102941-1-shy828301@gmail.com> <20220228235741.102941-4-shy828301@gmail.com> From: Miaohe Lin Message-ID: <6177c880-a34e-2539-764a-0de38c0cbc11@huawei.com> Date: Wed, 2 Mar 2022 11:21:07 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20220228235741.102941-4-shy828301@gmail.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 6B6C640003 X-Stat-Signature: 7oqg83dy8xoisd8ntdtfyfh7ipneygkf X-Rspam-User: Authentication-Results: imf04.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf04.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-Rspamd-Server: rspam03 X-HE-Tag: 1646191272-328276 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2022/3/1 7:57, Yang Shi wrote: > The DAX vma may be seen by khugepaged when the mm has other khugepaged > suitable vmas. So khugepaged may try to collapse THP for DAX vma, but > it will fail due to page sanity check, for example, page is not > on LRU. Yep. There is PageLRU check in khugepaged_scan_{file,pmd}. > > So it is not harmful, but it is definitely pointless to run khugepaged > against DAX vma, so skip it in early check. > This patch looks good to me. Thanks. Reviewed-by: Miaohe Lin > Signed-off-by: Yang Shi > --- > mm/khugepaged.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 82c71c6da9ce..a0e4fa33660e 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -448,6 +448,10 @@ static bool hugepage_vma_check(struct vm_area_struct *vma, > if (vm_flags & VM_NO_KHUGEPAGED) > return false; > > + /* Don't run khugepaged against DAX vma */ > + if (vma_is_dax(vma)) > + return false; > + > if (vma->vm_file && !IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - > vma->vm_pgoff, HPAGE_PMD_NR)) > return false; >