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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 E8D51C433DB for ; Thu, 21 Jan 2021 17:10:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A28FD23A5B for ; Thu, 21 Jan 2021 17:10:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388535AbhAURKj (ORCPT ); Thu, 21 Jan 2021 12:10:39 -0500 Received: from mx2.suse.de ([195.135.220.15]:47266 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388501AbhAURKg (ORCPT ); Thu, 21 Jan 2021 12:10:36 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 0C444AAAE; Thu, 21 Jan 2021 17:09:54 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 1FFAADA6E3; Thu, 21 Jan 2021 18:07:57 +0100 (CET) Date: Thu, 21 Jan 2021 18:07:57 +0100 From: David Sterba To: Su Yue Cc: linux-btrfs@vger.kernel.org, stable@vger.kernel.org, Erhard F , dave@stgolabs.net Subject: Re: [PATCH] btrfs: fix lockdep warning due to seqcount_mutex_init() with wrong address Message-ID: <20210121170756.GE6430@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Su Yue , linux-btrfs@vger.kernel.org, stable@vger.kernel.org, Erhard F , dave@stgolabs.net References: <20210121113910.14681-1-l@damenly.su> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210121113910.14681-1-l@damenly.su> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Adding Davidlohr to CC as it's about reverting his patch. In d5c8238849e7 ("btrfs: convert data_seqcount to seqcount_mutex_t") the seqcount_mutex_t was added as an annotation for lockep so by revert we'd lose that again. On Thu, Jan 21, 2021 at 07:39:10PM +0800, Su Yue wrote: > while running xfstests on 32 bits test box, many tests failed because of > warnings in dmesg. One of those warnings(btrfs/003): > ======================================================================== > [ 66.441305] ------------[ cut here ]------------ > [ 66.441317] WARNING: CPU: 6 PID: 9251 at include/linux/seqlock.h:279 btrfs_remove_chunk+0x58b/0x7b0 [btrfs] > [ 66.441446] CPU: 6 PID: 9251 Comm: btrfs Tainted: G O 5.11.0-rc4-custom+ #5 > [ 66.441449] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ArchLinux 1.14.0-1 04/01/2014 > [ 66.441451] EIP: btrfs_remove_chunk+0x58b/0x7b0 [btrfs] > [ 66.441472] EAX: 00000000 EBX: 00000001 ECX: c576070c EDX: c6b15803 > [ 66.441475] ESI: 10000000 EDI: 00000000 EBP: c56fbcfc ESP: c56fbc70 > [ 66.441477] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010246 > [ 66.441481] CR0: 80050033 CR2: 05c8da20 CR3: 04b20000 CR4: 00350ed0 > [ 66.441485] Call Trace: > [ 66.441510] btrfs_relocate_chunk+0xb1/0x100 [btrfs] > [ 66.441529] ? btrfs_lookup_block_group+0x17/0x20 [btrfs] > [ 66.441562] btrfs_balance+0x8ed/0x13b0 [btrfs] > [ 66.441586] ? btrfs_ioctl_balance+0x333/0x3c0 [btrfs] > [ 66.441619] ? __this_cpu_preempt_check+0xf/0x11 > [ 66.441643] btrfs_ioctl_balance+0x333/0x3c0 [btrfs] > [ 66.441664] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] > [ 66.441683] btrfs_ioctl+0x414/0x2ae0 [btrfs] > [ 66.441700] ? __lock_acquire+0x35f/0x2650 > [ 66.441717] ? lockdep_hardirqs_on+0x87/0x120 > [ 66.441720] ? lockdep_hardirqs_on_prepare+0xd0/0x1e0 > [ 66.441724] ? call_rcu+0x2d3/0x530 > [ 66.441731] ? __might_fault+0x41/0x90 > [ 66.441736] ? kvm_sched_clock_read+0x15/0x50 > [ 66.441740] ? sched_clock+0x8/0x10 > [ 66.441745] ? sched_clock_cpu+0x13/0x180 > [ 66.441750] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] > [ 66.441750] ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] > [ 66.441768] __ia32_sys_ioctl+0x165/0x8a0 > [ 66.441773] ? __this_cpu_preempt_check+0xf/0x11 > [ 66.441785] ? __might_fault+0x89/0x90 > [ 66.441791] __do_fast_syscall_32+0x54/0x80 > [ 66.441796] do_fast_syscall_32+0x32/0x70 > [ 66.441801] do_SYSENTER_32+0x15/0x20 > [ 66.441805] entry_SYSENTER_32+0x9f/0xf2 > [ 66.441808] EIP: 0xab7b5549 > [ 66.441814] EAX: ffffffda EBX: 00000003 ECX: c4009420 EDX: bfa91f5c > [ 66.441816] ESI: 00000003 EDI: 00000001 EBP: 00000000 ESP: bfa91e98 > [ 66.441818] DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 007b EFLAGS: 00000292 > [ 66.441833] irq event stamp: 42579 > [ 66.441835] hardirqs last enabled at (42585): [] console_unlock+0x495/0x590 > [ 66.441838] hardirqs last disabled at (42590): [] console_unlock+0x405/0x590 > [ 66.441840] softirqs last enabled at (41698): [] call_on_stack+0x1c/0x60 > [ 66.441843] softirqs last disabled at (41681): [] call_on_stack+0x1c/0x60 > [ 66.441846] ---[ end trace 7a9311b3f90a392e ]--- > ======================================================================== > > ======================================================================== > btrfs_remove_chunk+0x58b/0x7b0: > __seqprop_mutex_assert at linux/./include/linux/seqlock.h:279 > (inlined by) btrfs_device_set_bytes_used at linux/fs/btrfs/volumes.h:212 > (inlined by) btrfs_remove_chunk at linux/fs/btrfs/volumes.c:2994 > ======================================================================== > > The warning is produced by lockdep_assert_held() in > __seqprop_mutex_assert() if CONFIG_LOCKDEP is enabled. > And "volumes.c:2994" is btrfs_device_set_bytes_used() with mutex lock > &fs_info->chunk_mutex hold already. > > After adding some debug prints, the cause was found that manyq > __alloc_device() are called with NULL @fs_info. Inside the function, > btrfs_device_data_ordered_init() is expanded to seqcount_mutex_init(). > In this scenario, its second parameter(&info->chunk_mutex) passed is > &NULL->chunk_mutex which equals to offsetof(struct btrfs_fs_info, > chunk_mutex) unexpectly. Thus, seqcount_mutex_init() is called in wrong > way. And later btrfs_get/set_device_*() helpers triger lockdep warnings. > > The complex solution is to delay the call of btrfs_device_data_ordered_ > init() so the lockdep functionality can work well. > It requires that no btrfs_get/set_device_*() is called between > btrfs_alloc_device with NULL @fs_info and the delayed > btrfs_device_data_ordered_init(). Otherwise, total_bytes, disk_total_ > bytes and bytes_uesed of device may be inconsistent in 32 bits > environments. If the fs_info is not available at all times, would it be possible to set it once it is? (And reset when the fs_info is released).