BTRFS: device fsid 5ac8a51e-da3a-4998-8e66-e1df06b87bc8 devid 1 transid 8 /dev/loop1 scanned by syz-executor.1 (6194)
======================================================
WARNING: possible circular locking dependency detected
5.15.116-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.1/6194 is trying to acquire lock:
ffff0000c08808b0 (&type->i_mutex_dir_key#2){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
ffff0000c08808b0 (&type->i_mutex_dir_key#2){++++}-{3:3}, at: lookup_slow+0x50/0x84 fs/namei.c:1675

but task is already holding lock:
ffff0000fb0d8ce0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_free_stale_devices+0x158/0x9ec fs/btrfs/volumes.c:603

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&fs_devs->device_list_mutex){+.+.}-{3:3}:
       __mutex_lock_common+0x194/0x2154 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0xa4/0xf8 kernel/locking/mutex.c:743
       insert_dev_extents fs/btrfs/block-group.c:2345 [inline]
       btrfs_create_pending_block_groups+0x490/0xebc fs/btrfs/block-group.c:2395
       __btrfs_end_transaction+0x13c/0x610 fs/btrfs/transaction.c:1007
       btrfs_end_transaction+0x24/0x34 fs/btrfs/transaction.c:1043
       find_free_extent_update_loop fs/btrfs/extent-tree.c:4044 [inline]
       find_free_extent+0x32b0/0x44c8 fs/btrfs/extent-tree.c:4393
       btrfs_reserve_extent+0x1b4/0x43c fs/btrfs/extent-tree.c:4474
       cow_file_range+0x4f0/0xb74 fs/btrfs/inode.c:1181
       btrfs_run_delalloc_range+0x314/0x12cc fs/btrfs/inode.c:2018
       writepage_delalloc+0x1d4/0x434 fs/btrfs/extent_io.c:3802
       __extent_writepage+0x624/0xcbc fs/btrfs/extent_io.c:4108
       extent_write_cache_pages fs/btrfs/extent_io.c:5029 [inline]
       extent_writepages+0x9b0/0x1268 fs/btrfs/extent_io.c:5156
       btrfs_writepages+0x28/0x38 fs/btrfs/inode.c:8568
       do_writepages+0x39c/0x5ec mm/page-writeback.c:2364
       filemap_fdatawrite_wbc+0x1c8/0x228 mm/filemap.c:400
       start_delalloc_inodes+0x630/0xa30 fs/btrfs/inode.c:10064
       btrfs_start_delalloc_roots+0x5e4/0x898 fs/btrfs/inode.c:10143
       shrink_delalloc fs/btrfs/space-info.c:538 [inline]
       flush_space+0x5b0/0xc94 fs/btrfs/space-info.c:646
       btrfs_async_reclaim_metadata_space+0x6c8/0x80c fs/btrfs/space-info.c:953
       process_one_work+0x790/0x11b8 kernel/workqueue.c:2307
       worker_thread+0x910/0x1034 kernel/workqueue.c:2454
       kthread+0x37c/0x45c kernel/kthread.c:319
       ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:870

-> #2 (sb_internal#3){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1742 [inline]
       sb_start_intwrite include/linux/fs.h:1859 [inline]
       start_transaction+0x644/0x1480 fs/btrfs/transaction.c:677
       btrfs_join_transaction+0x30/0x40 fs/btrfs/transaction.c:790
       btrfs_dirty_inode+0xb4/0x1c0 fs/btrfs/inode.c:6322
       btrfs_update_time+0x248/0x270 fs/btrfs/inode.c:6364
       inode_update_time fs/inode.c:1787 [inline]
       touch_atime+0x434/0xa4c fs/inode.c:1860
       file_accessed include/linux/fs.h:2447 [inline]
       btrfs_file_mmap+0xb0/0x11c fs/btrfs/file.c:2424
       call_mmap include/linux/fs.h:2108 [inline]
       mmap_region+0xcb4/0x12f0 mm/mmap.c:1791
       do_mmap+0x6c0/0xcec mm/mmap.c:1575
       vm_mmap_pgoff+0x1a4/0x2b4 mm/util.c:551
       ksys_mmap_pgoff+0x458/0x668 mm/mmap.c:1624
       __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
       __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
       __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #1 (&mm->mmap_lock){++++}-{3:3}:
       __might_fault+0xc8/0x128 mm/memory.c:5311
       filldir64+0x2bc/0x9e4 fs/readdir.c:335
       dir_emit_dot include/linux/fs.h:3605 [inline]
       dir_emit_dots include/linux/fs.h:3616 [inline]
       dcache_readdir+0x134/0x678 fs/libfs.c:196
       iterate_dir+0x1f4/0x4e4
       __do_sys_getdents64 fs/readdir.c:369 [inline]
       __se_sys_getdents64 fs/readdir.c:354 [inline]
       __arm64_sys_getdents64+0x1c4/0x4c4 fs/readdir.c:354
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

-> #0 (&type->i_mutex_dir_key#2){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3787 [inline]
       __lock_acquire+0x32cc/0x7620 kernel/locking/lockdep.c:5011
       lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
       down_read+0xc0/0x398 kernel/locking/rwsem.c:1488
       inode_lock_shared include/linux/fs.h:797 [inline]
       lookup_slow+0x50/0x84 fs/namei.c:1675
       walk_component+0x394/0x4cc fs/namei.c:1972
       lookup_last fs/namei.c:2427 [inline]
       path_lookupat+0x13c/0x3d0 fs/namei.c:2451
       filename_lookup+0x1c4/0x4c8 fs/namei.c:2480
       kern_path+0x4c/0x194 fs/namei.c:2570
       lookup_bdev+0xc0/0x25c block/bdev.c:979
       device_matched fs/btrfs/volumes.c:563 [inline]
       btrfs_free_stale_devices+0x61c/0x9ec fs/btrfs/volumes.c:608
       btrfs_scan_one_device+0x438/0x5f8 fs/btrfs/volumes.c:1440
       btrfs_mount_root+0x424/0x7f8 fs/btrfs/super.c:1716
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
       vfs_get_tree+0x90/0x274 fs/super.c:1508
       fc_mount fs/namespace.c:1000 [inline]
       vfs_kern_mount+0xdc/0x178 fs/namespace.c:1030
       btrfs_mount+0x328/0x9b8 fs/btrfs/super.c:1812
       legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
       vfs_get_tree+0x90/0x274 fs/super.c:1508
       do_new_mount+0x25c/0x8c4 fs/namespace.c:2994
       path_mount+0x590/0x104c fs/namespace.c:3324
       do_mount fs/namespace.c:3337 [inline]
       __do_sys_mount fs/namespace.c:3545 [inline]
       __se_sys_mount fs/namespace.c:3522 [inline]
       __arm64_sys_mount+0x510/0x5e0 fs/namespace.c:3522
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
       do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
       el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
       el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
       el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

other info that might help us debug this:

Chain exists of:
  &type->i_mutex_dir_key#2 --> sb_internal#3 --> &fs_devs->device_list_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&fs_devs->device_list_mutex);
                               lock(sb_internal#3);
                               lock(&fs_devs->device_list_mutex);
  lock(&type->i_mutex_dir_key#2);

 *** DEADLOCK ***

2 locks held by syz-executor.1/6194:
 #0: ffff800014f85468 (uuid_mutex){+.+.}-{3:3}, at: btrfs_mount_root+0x234/0x7f8 fs/btrfs/super.c:1709
 #1: ffff0000fb0d8ce0 (&fs_devs->device_list_mutex){+.+.}-{3:3}, at: btrfs_free_stale_devices+0x158/0x9ec fs/btrfs/volumes.c:603

stack backtrace:
CPU: 1 PID: 6194 Comm: syz-executor.1 Not tainted 5.15.116-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 dump_stack+0x1c/0x58 lib/dump_stack.c:113
 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2011
 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain kernel/locking/lockdep.c:3787 [inline]
 __lock_acquire+0x32cc/0x7620 kernel/locking/lockdep.c:5011
 lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5622
 down_read+0xc0/0x398 kernel/locking/rwsem.c:1488
 inode_lock_shared include/linux/fs.h:797 [inline]
 lookup_slow+0x50/0x84 fs/namei.c:1675
 walk_component+0x394/0x4cc fs/namei.c:1972
 lookup_last fs/namei.c:2427 [inline]
 path_lookupat+0x13c/0x3d0 fs/namei.c:2451
 filename_lookup+0x1c4/0x4c8 fs/namei.c:2480
 kern_path+0x4c/0x194 fs/namei.c:2570
 lookup_bdev+0xc0/0x25c block/bdev.c:979
 device_matched fs/btrfs/volumes.c:563 [inline]
 btrfs_free_stale_devices+0x61c/0x9ec fs/btrfs/volumes.c:608
 btrfs_scan_one_device+0x438/0x5f8 fs/btrfs/volumes.c:1440
 btrfs_mount_root+0x424/0x7f8 fs/btrfs/super.c:1716
 legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
 vfs_get_tree+0x90/0x274 fs/super.c:1508
 fc_mount fs/namespace.c:1000 [inline]
 vfs_kern_mount+0xdc/0x178 fs/namespace.c:1030
 btrfs_mount+0x328/0x9b8 fs/btrfs/super.c:1812
 legacy_get_tree+0xd4/0x16c fs/fs_context.c:610
 vfs_get_tree+0x90/0x274 fs/super.c:1508
 do_new_mount+0x25c/0x8c4 fs/namespace.c:2994
 path_mount+0x590/0x104c fs/namespace.c:3324
 do_mount fs/namespace.c:3337 [inline]
 __do_sys_mount fs/namespace.c:3545 [inline]
 __se_sys_mount fs/namespace.c:3522 [inline]
 __arm64_sys_mount+0x510/0x5e0 fs/namespace.c:3522
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:596
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:614
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
BTRFS info (device loop1): using xxhash64 (xxhash64-generic) checksum algorithm
BTRFS info (device loop1): using free space tree
BTRFS info (device loop1): has skinny extents
BTRFS info (device loop1): enabling ssd optimizations
BTRFS info (device loop1): checking UUID tree