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 D03ABC433F5 for ; Tue, 19 Apr 2022 16:06:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354430AbiDSQJX (ORCPT ); Tue, 19 Apr 2022 12:09:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354437AbiDSQJS (ORCPT ); Tue, 19 Apr 2022 12:09:18 -0400 Received: from nibbler.cm4all.net (nibbler.cm4all.net [IPv6:2001:8d8:970:e500:82:165:145:151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 143803B29D for ; Tue, 19 Apr 2022 09:06:33 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by nibbler.cm4all.net (Postfix) with ESMTP id D07E4C00B9 for ; Tue, 19 Apr 2022 18:06:30 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at nibbler.cm4all.net Received: from nibbler.cm4all.net ([127.0.0.1]) by localhost (nibbler.cm4all.net [127.0.0.1]) (amavisd-new, port 10024) with LMTP id lsEuYVWbRmu0 for ; Tue, 19 Apr 2022 18:06:23 +0200 (CEST) Received: from zero.intern.cm-ag (zero.intern.cm-ag [172.30.16.10]) by nibbler.cm4all.net (Postfix) with SMTP id 03E2DC00E1 for ; Tue, 19 Apr 2022 18:06:20 +0200 (CEST) Received: (qmail 26839 invoked from network); 19 Apr 2022 21:56:21 +0200 Received: from unknown (HELO rabbit.intern.cm-ag) (172.30.3.1) by zero.intern.cm-ag with SMTP; 19 Apr 2022 21:56:21 +0200 Received: by rabbit.intern.cm-ag (Postfix, from userid 1023) id C913A460F19; Tue, 19 Apr 2022 18:06:19 +0200 (CEST) Date: Tue, 19 Apr 2022 18:06:19 +0200 From: Max Kellermann To: David Howells Cc: Max Kellermann , linux-cachefs@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: fscache corruption in Linux 5.17? Message-ID: References: <507518.1650383808@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <507518.1650383808@warthog.procyon.org.uk> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 2022/04/19 17:56, David Howells wrote: > This is weird. It looks like content got slid down by 31 bytes and 31 zero > bytes got added at the end. I'm not sure how fscache would achieve that - > nfs's implementation should only be dealing with pages. Did you read this part of my email?: On 2022/04/12 17:10, Max Kellermann wrote: > The corruption can be explained by WordPress commit > https://github.com/WordPress/WordPress/commit/07855db0ee8d5cff2 which > makes the file 31 bytes longer (185055 -> 185086). The "broken" web > server sees the new contents until offset 184320 (= 45 * 4096), but > sees the old contents from there on; followed by 31 null bytes > (because the kernel reads past the end of the cache?). My theory was that fscache shows a mix of old and new pages after the file was modified. Does this make sense? Is there anything I can do to give you data from this server's cache?