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 0517BC433EF for ; Wed, 15 Jun 2022 23:57:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 324906B0071; Wed, 15 Jun 2022 19:57:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2D39A6B0072; Wed, 15 Jun 2022 19:57:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 19BAB6B0074; Wed, 15 Jun 2022 19:57:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 0B8136B0071 for ; Wed, 15 Jun 2022 19:57:47 -0400 (EDT) Received: from smtpin31.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id CDA7A20E3D for ; Wed, 15 Jun 2022 23:57:46 +0000 (UTC) X-FDA: 79582135332.31.3135444 Received: from mail-pl1-f172.google.com (mail-pl1-f172.google.com [209.85.214.172]) by imf06.hostedemail.com (Postfix) with ESMTP id 5EEB1180096 for ; Wed, 15 Jun 2022 23:57:46 +0000 (UTC) Received: by mail-pl1-f172.google.com with SMTP id r1so11699930plo.10 for ; Wed, 15 Jun 2022 16:57:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ogTieaFqi6CNOTX3+q0iK+76j2aYotKQRzqOleB5Sgo=; b=MbATXkKayIK3jtaXf7FFj7hMDbsDmZNluuRpWCQTBCAtUaMKLwy36mTr2OhTZGv2Vz ksKW1th55SbzG1rf0Ht5GJSU2gK5BVClFDNwsHFuTjsqzNFCTB4BAU371VaQZlSsg4xq BaQI5dACSxwUHvyxY/k+3NU1RYTXmblT+vCw+X6sH3obsOTcbKGhX3itBuh70WquUD7g g3aT9Yy1mcBvg80dHB7GY1VhkgRr+3ufvMpVlOVcAqMWDfZskla6UTpbct7/fMXwAG0f UCS0IiO2RMZTkK+Yso2JBZN3MehQJpe3tPSxj0wj0CLL0zkVvQ1I/jDOgM9WPaqjbAJk B/dw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ogTieaFqi6CNOTX3+q0iK+76j2aYotKQRzqOleB5Sgo=; b=A2gWkmfAgs0rdKi83yUcjRvSd82UCQjHK86vmJ8WdWCV8NJLPefJVdNSzKGLTIWTtz EZiLTjbrwwFJXTLtGbiTE3+UhEgontj23GtwoVtnMYha3ZUYb4Njmevmx02BsOOtANiA 3Z0obJ9HZXgS5W5q8cVez6IiikuTJcQLANONYh2V0NW4zshVhrkzBvwvEOPE1Bp9i/iJ /Y++z05FM1o6MFrbdAwH4NZvwYIGkioxIDAyRPipgv7tw37PSskFFNT2n2xh/O7EIE75 AF7woe7p2TnrFWiceo95k8b9bAcJdiB1Qu0FMOr2w1JaNTGZzBsOgT7g8SIThT26ozCV RH5A== X-Gm-Message-State: AJIora82yv5gtqqrbqUJFW2b8iy7oeEE3oIWhJOcvcIgig9HiDmePtua lWr52Sl2FZprziJG6tiU9buHiQ== X-Google-Smtp-Source: AGRyM1vMKwU5cbMs69vbFx1BXgBv8oNQR+IcWe+vYc8ooIejYyS6Q4MnouC1XzURuXko6WkekW38sQ== X-Received: by 2002:a17:902:ea0f:b0:164:1a71:bef1 with SMTP id s15-20020a170902ea0f00b001641a71bef1mr1800234plg.52.1655337465130; Wed, 15 Jun 2022 16:57:45 -0700 (PDT) Received: from google.com (55.212.185.35.bc.googleusercontent.com. [35.185.212.55]) by smtp.gmail.com with ESMTPSA id x13-20020a170902a38d00b00163f183ab76sm195015pla.152.2022.06.15.16.57.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jun 2022 16:57:44 -0700 (PDT) Date: Wed, 15 Jun 2022 16:57:40 -0700 From: Zach O'Keefe To: Yang Shi Cc: vbabka@suse.cz, kirill.shutemov@linux.intel.com, willy@infradead.org, linmiaohe@huawei.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v4 PATCH 3/7] mm: khugepaged: better comments for anon vma check in hugepage_vma_revalidate Message-ID: References: <20220615172926.546974-1-shy828301@gmail.com> <20220615172926.546974-4-shy828301@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220615172926.546974-4-shy828301@gmail.com> ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655337466; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ogTieaFqi6CNOTX3+q0iK+76j2aYotKQRzqOleB5Sgo=; b=j7mlnXt4EH7Hs4QjVpUQz1xUqJxp01e+CiAEKq0dgBqj01MGKI+Lw9zjrmPn/mL5U4ueaP wWpuZrpu62j6lOVKrZZcQhw6Oip4ci7+4hzcy3LFi0KFT3dVSnPAN43nqBAtrctJNJDMyl m+txTRLnZDdRh0cFaDI8vUhhhUz4JBg= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=MbATXkKa; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf06.hostedemail.com: domain of zokeefe@google.com designates 209.85.214.172 as permitted sender) smtp.mailfrom=zokeefe@google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655337466; a=rsa-sha256; cv=none; b=lwYP6Knwgg0TxBL2FQjo+zzKHSCvoFpTemqZpcbaXR7NWOff5GFwWwAaZDbdViy3cfKCsh XW04tcM0L9IYCFd9pby8hCnyJFl6EbwcF94AKr0D5X336PJb9W09uwBI88QBJLZd9JVnx2 XkTdOEo1BewUtRhyHWsscXQntz7f1O4= X-Stat-Signature: ubeqibkfbcyu8xb55s7rmcup9ug33hyx X-Rspamd-Queue-Id: 5EEB1180096 X-Rspam-User: X-Rspamd-Server: rspam05 Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=MbATXkKa; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf06.hostedemail.com: domain of zokeefe@google.com designates 209.85.214.172 as permitted sender) smtp.mailfrom=zokeefe@google.com X-HE-Tag: 1655337466-38123 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 15 Jun 10:29, Yang Shi wrote: > 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 > Reviewed-by: Zach O'Keefe