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dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=none action=none header.from=oracle.com; Received: from MN2PR10MB4128.namprd10.prod.outlook.com (2603:10b6:208:1d2::24) by BL0PR10MB2961.namprd10.prod.outlook.com (2603:10b6:208:33::31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3890.20; Fri, 26 Feb 2021 05:01:15 +0000 Received: from MN2PR10MB4128.namprd10.prod.outlook.com ([fe80::e5b0:9afa:a555:a125]) by MN2PR10MB4128.namprd10.prod.outlook.com ([fe80::e5b0:9afa:a555:a125%8]) with mapi id 15.20.3890.022; Fri, 26 Feb 2021 05:01:14 +0000 Subject: Re: [report] lockdep warning when mounting seed device To: Su Yue , Btrfs BTRFS References: From: Anand Jain Message-ID: <50ff53e3-6e6f-bc6d-31dc-ac376ed944ce@oracle.com> Date: Fri, 26 Feb 2021 13:01:02 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [39.109.186.25] X-ClientProxiedBy: SG2PR06CA0088.apcprd06.prod.outlook.com (2603:1096:3:14::14) To MN2PR10MB4128.namprd10.prod.outlook.com (2603:10b6:208:1d2::24) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.10.102] (39.109.186.25) by SG2PR06CA0088.apcprd06.prod.outlook.com (2603:1096:3:14::14) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3890.19 via Frontend Transport; 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Could you please try this [1] patch, [1] https://patchwork.kernel.org/project/linux-btrfs/patch/20200717100525.320697-1-anand.jain@oracle.com/ Patch [1] still relevant as the device_list_mutex in clone_fs_devices() is redundant. We could remove it as well. Thanks, Anand > Warning: > > [  104.348749] BTRFS: device fsid 9a34d68b-fd18-470c-8cfc-44916c364c76 > devid 1 transid 5 /dev/sdb1 scanned by mkfs.btrfs (627) > [  104.377243] BTRFS info (device sdb1): disk space caching is enabled > [  104.378091] BTRFS info (device sdb1): has skinny extents > [  104.378800] BTRFS info (device sdb1): flagging fs with big metadata > feature > [  104.512522] BTRFS info (device sdb1): relocating block group > 567279616 flags system|dup > [  104.535912] BTRFS info (device sdb1): relocating block group 22020096 > flags system|dup > [  104.571307] BTRFS info (device sdb1): disk added /dev/sdb2 > [  104.602831] BTRFS info (device sdb2): disk space caching is enabled > [  104.603692] BTRFS info (device sdb2): has skinny extents > > [  104.606389] ====================================================== > [  104.607212] WARNING: possible circular locking dependency detected > [  104.608025] 5.11.0-rc7-custom+ #55 Tainted: G           O > [  104.608790] ------------------------------------------------------ > [  104.609599] mount/670 is trying to acquire lock: > [  104.610207] ffffa2274d7158e8 > (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: > clone_fs_devices+0x4f/0x160 [btrfs] > [  104.611585] >               but task is already holding lock: > [  104.612334] ffffa22750e32f20 (btrfs-chunk-00){++++}-{3:3}, at: > __btrfs_tree_read_lock+0x2d/0x110 [btrfs] > [  104.651264] >               which lock already depends on the new lock. > > [  104.708041] >               the existing dependency chain (in reverse order) >               is: > [  104.743619] >               -> #1 (btrfs-chunk-00){++++}-{3:3}: > [  104.777693]        down_read_nested+0x4b/0x140 > [  104.794386]        __btrfs_tree_read_lock+0x2d/0x110 [btrfs] > [  104.811338]        btrfs_read_lock_root_node+0x36/0x50 [btrfs] > [  104.828574]        btrfs_search_slot+0x473/0x900 [btrfs] > [  104.845543]        btrfs_update_device+0x71/0x1a0 [btrfs] > [  104.862164]        btrfs_finish_chunk_alloc+0x121/0x490 [btrfs] > [  104.878474] btrfs_create_pending_block_groups+0x151/0x2c0 [btrfs] > [  104.894725]        btrfs_commit_transaction+0x82/0xb30 [btrfs] > [  104.910808]        btrfs_init_new_device+0x1015/0x14d0 [btrfs] > [  104.926879]        btrfs_ioctl+0x1ff/0x2fc0 [btrfs] > [  104.942996]        __x64_sys_ioctl+0x91/0xc0 > [  104.958874]        do_syscall_64+0x38/0x50 > [  104.974554]        entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [  104.990108] >               -> #0 (&fs_devs->device_list_mutex){+.+.}-{3:3}: > [  105.020508]        __lock_acquire+0x11e0/0x1ea0 > [  105.035759]        lock_acquire+0xd8/0x3c0 > [  105.050434]        __mutex_lock+0x8f/0x870 > [  105.064614]        mutex_lock_nested+0x1b/0x20 > [  105.078641]        clone_fs_devices+0x4f/0x160 [btrfs] > [  105.092984]        btrfs_read_chunk_tree+0x30e/0x7f0 [btrfs] > [  105.107031]        open_ctree+0xb40/0x176a [btrfs] > [  105.120673]        btrfs_mount_root.cold+0x12/0xeb [btrfs] > [  105.134564]        legacy_get_tree+0x34/0x60 > [  105.148347]        vfs_get_tree+0x2d/0xc0 > [  105.162053]        vfs_kern_mount.part.0+0x78/0xc0 > [  105.176072]        vfs_kern_mount+0x13/0x20 > [  105.189844]        btrfs_mount+0x11f/0x3c0 [btrfs] > [  105.203396]        legacy_get_tree+0x34/0x60 > [  105.217129]        vfs_get_tree+0x2d/0xc0 > [  105.230536]        path_mount+0x48c/0xd30 > [  105.243915]        __x64_sys_mount+0x108/0x140 > [  105.257030]        do_syscall_64+0x38/0x50 > [  105.270084]        entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [  105.283382] >               other info that might help us debug this: > > [  105.321699]  Possible unsafe locking scenario: > > [  105.347053]        CPU0                    CPU1 > [  105.359640]        ----                    ---- > [  105.372004]   lock(btrfs-chunk-00); > [  105.384023] lock(&fs_devs->device_list_mutex); > [  105.396858] lock(btrfs-chunk-00); > [  105.409215]   lock(&fs_devs->device_list_mutex); > [  105.421625] >                *** DEADLOCK *** > > [  105.457447] 3 locks held by mount/670: > [  105.469302]  #0: ffffa2270932e0e8 > (&type->s_umount_key#54/1){+.+.}-{3:3}, at: alloc_super+0xdf/0x3c0 > [  105.494413]  #1: ffffffffc0bdfdd0 (uuid_mutex){+.+.}-{3:3}, at: > btrfs_read_chunk_tree+0x5c/0x7f0 [btrfs] > [  105.521072]  #2: ffffa22750e32f20 (btrfs-chunk-00){++++}-{3:3}, at: > __btrfs_tree_read_lock+0x2d/0x110 [btrfs] > [  105.549753] >               stack backtrace: > [  105.578187] CPU: 6 PID: 670 Comm: mount Tainted: G           O > 5.11.0-rc7-custom+ #55 > [  105.607477] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), > BIOS ArchLinux 1.14.0-1 04/01/2014 > [  105.638608] Call Trace: > [  105.653967]  dump_stack+0x90/0xb8 > [  105.669419]  print_circular_bug.cold+0x13d/0x142 > [  105.684814]  check_noncircular+0xf2/0x110 > [  105.700322]  ? check_path.constprop.0+0x26/0x40 > [  105.715821]  __lock_acquire+0x11e0/0x1ea0 > [  105.731388]  ? __this_cpu_preempt_check+0x13/0x20 > [  105.747097]  ? lockdep_unlock+0x33/0xd0 > [  105.763012]  lock_acquire+0xd8/0x3c0 > [  105.779043]  ? clone_fs_devices+0x4f/0x160 [btrfs] > [  105.795343]  __mutex_lock+0x8f/0x870 > [  105.811251]  ? clone_fs_devices+0x4f/0x160 [btrfs] > [  105.827385]  ? lockdep_init_map_waits+0x51/0x250 > [  105.843343]  ? clone_fs_devices+0x4f/0x160 [btrfs] > [  105.859264]  ? debug_mutex_init+0x36/0x50 > [  105.875378]  ? __mutex_init+0x62/0x70 > [  105.891493]  mutex_lock_nested+0x1b/0x20 > [  105.907847]  clone_fs_devices+0x4f/0x160 [btrfs] > [  105.923756]  ? btrfs_get_64+0x63/0x110 [btrfs] > [  105.939389]  btrfs_read_chunk_tree+0x30e/0x7f0 [btrfs] > [  105.954580]  open_ctree+0xb40/0x176a [btrfs] > [  105.969477]  ? bdi_register_va+0x1b/0x20 > [  105.983674]  ? super_setup_bdi_name+0x79/0xd0 > [  105.997611]  btrfs_mount_root.cold+0x12/0xeb [btrfs] > [  106.011564]  ? __kmalloc_track_caller+0x217/0x3b0 > [  106.026013]  legacy_get_tree+0x34/0x60 > [  106.040045]  vfs_get_tree+0x2d/0xc0 > [  106.053904]  vfs_kern_mount.part.0+0x78/0xc0 > [  106.067296]  vfs_kern_mount+0x13/0x20 > [  106.080125]  btrfs_mount+0x11f/0x3c0 [btrfs] > [  106.093144]  ? kfree+0x5ff/0x670 > [  106.106064]  ? __kmalloc_track_caller+0x217/0x3b0 > [  106.119249]  legacy_get_tree+0x34/0x60 > [  106.132216]  vfs_get_tree+0x2d/0xc0 > [  106.145225]  path_mount+0x48c/0xd30 > [  106.157899]  __x64_sys_mount+0x108/0x140 > [  106.170654]  do_syscall_64+0x38/0x50 > [  106.183208]  entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [  106.196111] RIP: 0033:0x7fafa8869ebe > [  106.208994] Code: 48 8b 0d b5 0f 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 > 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f > 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 82 0f 0c 00 f7 d8 64 89 01 48 > [  106.250073] RSP: 002b:00007ffc04365b98 EFLAGS: 00000246 ORIG_RAX: > 00000000000000a5 > [  106.278571] RAX: ffffffffffffffda RBX: 00007fafa8994264 RCX: > 00007fafa8869ebe > [  106.294048] RDX: 0000556726a02e00 RSI: 00005567269fc690 RDI: > 00005567269fc670 > [  106.309646] RBP: 00005567269fc440 R08: 0000000000000000 R09: > 00007fafa892ba60 > [  106.325336] R10: 0000000000000000 R11: 0000000000000246 R12: > 0000000000000000 > [  106.340847] R13: 00005567269fc670 R14: 0000556726a02e00 R15: > 00005567269fc440 > [  106.357929] BTRFS info (device sdb2): checking UUID tree