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=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 68C7EC74A3A for ; Wed, 10 Jul 2019 17:51:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4348C2087F for ; Wed, 10 Jul 2019 17:51:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="UZK6Vmsl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728043AbfGJRve (ORCPT ); Wed, 10 Jul 2019 13:51:34 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:45941 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727102AbfGJRve (ORCPT ); Wed, 10 Jul 2019 13:51:34 -0400 Received: by mail-pl1-f195.google.com with SMTP id y8so1576024plr.12 for ; Wed, 10 Jul 2019 10:51:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=uKVGZA2rdeScy3bwyoxpCnlfJ0pW69jxWknu9B37i2E=; b=UZK6Vmsl0GscAoMkvtUuBih99iOojK11B4bvX2Y3xO14yXORhC/0bcYZdxrAsSPYm0 3cghVrqwrNceZtWVPS2OmuOTg8jqhlsmP74StkkSqNt3ZRtstSVQ2rqC4oa52GhxYWYP szwnVtXKZPWmkwhy+poSNKK7HVBlvyd6PMe0AaVqrSmXPBtUAl6kBVIteBLTp/hzC6Ca k1HlOYguhdbAY0QSGQauUptYzwBBp44xNU1GSIkDnJl7S8EffJ29kXDie/6fcE2Xx+9R LzD9VvJHiopZz0iXo4NPCaCU19GtW2sXRJBRyMMl3LJh1svVA5UnfRFEThRroQv5H/BN 8IaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=uKVGZA2rdeScy3bwyoxpCnlfJ0pW69jxWknu9B37i2E=; b=htbC5RBJImuYpijpg4pvKd0b7mvyp3KVcsA60oWiVLwRuYSNsS9Zx9Z6vIedMnEgVu g2DjmdLPDx6JdzmdWibBetOblrT55B9x3F7OY1ypxg/ToqAbW+dRZ/2emxP3Msa3M5pl Yi/l94NY3Nj6+gBLhOYq7n9Ku8Y6sq9mrZAMxltxkZZGMVCX0ttK1qy8Wv5Xx+FE676m E7E6Dhc3yTcNqm42DGz6ybaSJRTMCHOg9p93WdrHroAvp4qc7OkuJ37s2BFIuVT7FkKZ LpXi/0DNw0+NEqyPSn0vx6Iu6pK5rW3SI7rs3Fu0fiRlvYL++Qo0CSu2h+zBKnVohx/B uitg== X-Gm-Message-State: APjAAAVhWJmkNQ9BLnOOpPYrVnqyTHMplaWjXEIAf3OSIRXEnLrgaSeg 8WDXs+oZFjHaPrrmBDb1mr7Yug== X-Google-Smtp-Source: APXvYqxf3k6wj0r1DWMxtICEKSsf7cXHz1s9bD0kZqyeu5LkX+cE8uIy0dD31APMZFjW0w+y3Coc3A== X-Received: by 2002:a17:902:1486:: with SMTP id k6mr39639657pla.177.1562781093710; Wed, 10 Jul 2019 10:51:33 -0700 (PDT) Received: from localhost ([2620:10d:c091:500::2:5b9d]) by smtp.gmail.com with ESMTPSA id j15sm2877546pfr.146.2019.07.10.10.51.32 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 10 Jul 2019 10:51:32 -0700 (PDT) Date: Wed, 10 Jul 2019 13:51:31 -0400 From: Johannes Weiner To: Song Liu Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, matthew.wilcox@oracle.com, kirill.shutemov@linux.intel.com, kernel-team@fb.com, william.kucharski@oracle.com, akpm@linux-foundation.org, hdanton@sina.com Subject: Re: [PATCH v9 1/6] filemap: check compound_head(page)->mapping in filemap_fault() Message-ID: <20190710175131.GB11197@cmpxchg.org> References: <20190625001246.685563-1-songliubraving@fb.com> <20190625001246.685563-2-songliubraving@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190625001246.685563-2-songliubraving@fb.com> User-Agent: Mutt/1.12.0 (2019-05-25) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Jun 24, 2019 at 05:12:41PM -0700, Song Liu wrote: > Currently, filemap_fault() avoids trace condition with truncate by > checking page->mapping == mapping. This does not work for compound > pages. This patch let it check compound_head(page)->mapping instead. > > Acked-by: Rik van Riel > Signed-off-by: Song Liu > --- > mm/filemap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index df2006ba0cfa..f5b79a43946d 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2517,7 +2517,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) > goto out_retry; > > /* Did it get truncated? */ > - if (unlikely(page->mapping != mapping)) { > + if (unlikely(compound_head(page)->mapping != mapping)) { There is another check like these in pagecache_get_page(), which is used by find_lock_page() and thus the truncate code (partial page truncate calls, but this could happen against read-only cache).