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 125CCC7EE29 for ; Fri, 9 Jun 2023 17:36:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230499AbjFIRgl (ORCPT ); Fri, 9 Jun 2023 13:36:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230487AbjFIRgk (ORCPT ); Fri, 9 Jun 2023 13:36:40 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3EC65E4E; Fri, 9 Jun 2023 10:36:39 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id E44551FE10; Fri, 9 Jun 2023 17:36:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1686332197; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XsENri2S9pvn1qva5u81VJpotBG57Jbvi1S1O6Xiv0Y=; b=FvNeMT2sAHqgex5YwtzgiL4bKlfJoNay15IlruWRKOQJvJBsFslyRdcwVa+o7uDnJP/1aI wX9zXMMrpH2MjP6PCbl84d4vP22vXorx9g1LYxWQ+94cqiB3p0DGGTum9cmboclRsE4yQD B1UBinfgFKvSVw9uZo9F5Dw4Keg4Jgk= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1686332197; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XsENri2S9pvn1qva5u81VJpotBG57Jbvi1S1O6Xiv0Y=; b=TziDihUDDOcgL9DY4Ncl70gVbdcQ2NItiJhfQjuD0ICNx/PPBR2p/IZ7J4/bFRYP0UNExU HzmxMv9z+eFb5RBg== Received: from ds.suse.cz (ds.suse.cz [10.100.12.205]) by relay2.suse.de (Postfix) with ESMTP id 9C38F2C141; Fri, 9 Jun 2023 17:36:37 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id ABCDBDA85A; Fri, 9 Jun 2023 19:30:21 +0200 (CEST) Date: Fri, 9 Jun 2023 19:30:21 +0200 From: David Sterba To: Dave Chinner Cc: David Sterba , syzbot , clm@fb.com, dsterba@suse.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [btrfs?] INFO: task hung in btrfs_sync_file (2) Message-ID: <20230609173021.GD12828@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <00000000000086021605fd1b484c@google.com> <20230606142405.GI25292@twin.jikos.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Wed, Jun 07, 2023 at 08:45:32AM +1000, Dave Chinner wrote: > On Tue, Jun 06, 2023 at 04:24:05PM +0200, David Sterba wrote: > > On Thu, Jun 01, 2023 at 06:15:06PM -0700, syzbot wrote: > > > RIP: 0010:rep_movs_alternative+0x33/0xb0 arch/x86/lib/copy_user_64.S:56 > > > Code: 46 83 f9 08 73 21 85 c9 74 0f 8a 06 88 07 48 ff c7 48 ff c6 48 ff c9 75 f1 c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 8b 06 <48> 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 df 83 f9 08 73 e8 eb > > > RSP: 0018:ffffc9000becf728 EFLAGS: 00050206 > > > RAX: 0000000000000000 RBX: 0000000000000038 RCX: 0000000000000038 > > > RDX: fffff520017d9efb RSI: ffffc9000becf7a0 RDI: 0000000020000120 > > > RBP: 0000000020000120 R08: 0000000000000000 R09: fffff520017d9efa > > > R10: ffffc9000becf7d7 R11: 0000000000000001 R12: ffffc9000becf7a0 > > > R13: 0000000020000158 R14: 0000000000000000 R15: ffffc9000becf7a0 > > > copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline] > > > raw_copy_to_user arch/x86/include/asm/uaccess_64.h:133 [inline] > > > _copy_to_user lib/usercopy.c:41 [inline] > > > _copy_to_user+0xab/0xc0 lib/usercopy.c:34 > > > copy_to_user include/linux/uaccess.h:191 [inline] > > > fiemap_fill_next_extent+0x217/0x370 fs/ioctl.c:144 > > > emit_fiemap_extent+0x18e/0x380 fs/btrfs/extent_io.c:2616 > > > fiemap_process_hole+0x516/0x610 fs/btrfs/extent_io.c:2874 > > > > and extent enumeration from FIEMAP, this would qualify as a stress on > > the inode > > FWIW, when I've seen this sort of hang on XFS in past times, it's > been caused by a corrupt extent list or a circular reference in a > btree that the fuzzing introduced. Hence FIEMAP just keeps going > around in circles and never gets out of the loop to drop the inode > lock.... Thanks for the info. The provided reproducer was able to get the VM stuck in a few hours so there is some problem. The generated image does not show any obvious problem so it's either lack of 'check' capability or the problem happens at run time.