On 25/02/2021 12:39, Su Yue wrote:
While playing with seed device(misc/next and v5.11), lockdep complains
the following:
To reproduce:
dev1=/dev/sdb1
dev2=/dev/sdb2
umount /mnt
mkfs.btrfs -f $dev1
btrfstune -S 1 $dev1
mount $dev1 /mnt
btrfs device add $dev2 /mnt/ -f
umount /mnt
mount $dev2 /mnt
umount /mnt
In my understanding the commit 01d01caf19ff7c537527d352d169c4368375c0a1
(btrfs: move the chunk_mutex in btrfs_read_chunk_tree
fixed this bug in 5.9.
Could you please try this [1] patch,
[1]
https://patchwork.kernel.org/project/linux-btrfs/patch/20200717100525.320697-1-anand.j...@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
