loop4: detected capacity change from 0 to 32768 ====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.4.1090/10859 is trying to acquire lock: ffff888033fe8280 (&type->i_mutex_dir_key#5){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1044 [inline] ffff888033fe8280 (&type->i_mutex_dir_key#5){++++}-{4:4}, at: lookup_slow+0x46/0x70 fs/namei.c:1931 but task is already holding lock: ffff8880265758d0 (&fs_devs->device_list_mutex){+.+.}-{4:4}, at: device_list_add+0x487/0x2280 fs/btrfs/volumes.c:843 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&fs_devs->device_list_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x19e/0x1420 kernel/locking/mutex.c:794 insert_dev_extents fs/btrfs/block-group.c:2876 [inline] btrfs_create_pending_block_groups+0x77b/0x1b40 fs/btrfs/block-group.c:2927 __btrfs_end_transaction+0x140/0x640 fs/btrfs/transaction.c:1091 flush_space+0x406/0xe20 fs/btrfs/space-info.c:914 do_async_reclaim_metadata_space+0x3fc/0x960 fs/btrfs/space-info.c:1213 btrfs_async_reclaim_metadata_space+0x89/0xe0 fs/btrfs/space-info.c:1280 process_one_work kernel/workqueue.c:3302 [inline] process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #4 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x1a4/0xd60 fs/btrfs/transaction.c:324 start_transaction+0xb07/0x1790 fs/btrfs/transaction.c:719 btrfs_rebuild_free_space_tree+0xbb/0x6e0 fs/btrfs/free-space-tree.c:1335 btrfs_start_pre_rw_mount+0x1529/0x1f20 fs/btrfs/disk-io.c:3057 open_ctree+0x2e04/0x4220 fs/btrfs/disk-io.c:3654 btrfs_fill_super fs/btrfs/super.c:981 [inline] btrfs_get_tree_super fs/btrfs/super.c:1944 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline] btrfs_get_tree+0x1061/0x1910 fs/btrfs/super.c:2121 vfs_get_tree+0x92/0x2a0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3758 [inline] do_new_mount+0x341/0xd30 fs/namespace.c:3834 do_mount fs/namespace.c:4167 [inline] __do_sys_mount fs/namespace.c:4399 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4376 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5574 [inline] lock_release+0x199/0x3c0 kernel/locking/lockdep.c:5889 percpu_up_read include/linux/percpu-rwsem.h:112 [inline] __sb_end_write include/linux/fs/super.h:14 [inline] sb_end_intwrite+0x26/0x1c0 include/linux/fs/super.h:101 __btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1096 btrfs_dirty_inode+0x14c/0x190 fs/btrfs/inode.c:6451 file_update_time_flags+0x2cf/0x4a0 fs/inode.c:2420 btrfs_page_mkwrite+0x60a/0x1a60 fs/btrfs/file.c:1914 do_page_mkwrite+0x14d/0x310 mm/memory.c:3668 wp_page_shared mm/memory.c:4069 [inline] do_wp_page+0x19ba/0x4cc0 mm/memory.c:4288 handle_pte_fault mm/memory.c:6470 [inline] __handle_mm_fault mm/memory.c:6592 [inline] handle_mm_fault+0x151d/0x3170 mm/memory.c:6761 do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 -> #2 (sb_pagefaults#3){.+.+}-{0:0}: percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs/super.h:19 [inline] sb_start_pagefault include/linux/fs/super.h:159 [inline] btrfs_page_mkwrite+0x351/0x1a60 fs/btrfs/file.c:1873 do_page_mkwrite+0x14d/0x310 mm/memory.c:3668 do_shared_fault mm/memory.c:6012 [inline] do_fault mm/memory.c:6074 [inline] do_pte_missing+0x6dc/0x33f0 mm/memory.c:4550 handle_pte_fault mm/memory.c:6454 [inline] __handle_mm_fault mm/memory.c:6592 [inline] handle_mm_fault+0x1bd7/0x3170 mm/memory.c:6761 do_user_addr_fault+0x75b/0x1340 arch/x86/mm/fault.c:1385 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 -> #1 (&mm->mmap_lock){++++}-{4:4}: down_read_killable+0x50/0x340 kernel/locking/rwsem.c:1593 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:601 get_mmap_lock_carefully mm/mmap_lock.c:450 [inline] lock_mm_and_find_vma+0x2d7/0x340 mm/mmap_lock.c:501 do_user_addr_fault+0x330/0x1340 arch/x86/mm/fault.c:1357 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 filldir64+0x2b2/0x640 fs/readdir.c:368 dir_emit include/linux/fs.h:3572 [inline] offset_dir_emit fs/libfs.c:499 [inline] offset_iterate_dir fs/libfs.c:515 [inline] offset_readdir+0x3fc/0x530 fs/libfs.c:564 iterate_dir+0x399/0x570 fs/readdir.c:110 __do_sys_getdents64 fs/readdir.c:399 [inline] __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&type->i_mutex_dir_key#5){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 down_read+0x47/0x2e0 kernel/locking/rwsem.c:1568 inode_lock_shared include/linux/fs.h:1044 [inline] lookup_slow+0x46/0x70 fs/namei.c:1931 walk_component fs/namei.c:2278 [inline] lookup_last fs/namei.c:2785 [inline] path_lookupat+0x3f5/0x8c0 fs/namei.c:2809 filename_lookup+0x256/0x5d0 fs/namei.c:2838 kern_path+0x3d/0x150 fs/namei.c:3044 is_same_device fs/btrfs/volumes.c:764 [inline] device_list_add+0xfd1/0x2280 fs/btrfs/volumes.c:898 btrfs_scan_one_device+0x3ef/0x680 fs/btrfs/volumes.c:1499 btrfs_get_tree_super fs/btrfs/super.c:1858 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline] btrfs_get_tree+0x4ab/0x1910 fs/btrfs/super.c:2121 vfs_get_tree+0x92/0x2a0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3758 [inline] do_new_mount+0x341/0xd30 fs/namespace.c:3834 do_mount fs/namespace.c:4167 [inline] __do_sys_mount fs/namespace.c:4399 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4376 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &type->i_mutex_dir_key#5 --> btrfs_trans_num_extwriters --> &fs_devs->device_list_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&fs_devs->device_list_mutex); lock(btrfs_trans_num_extwriters); lock(&fs_devs->device_list_mutex); rlock(&type->i_mutex_dir_key#5); *** DEADLOCK *** 2 locks held by syz.4.1090/10859: #0: ffffffff8ef7f800 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree_super fs/btrfs/super.c:1852 [inline] #0: ffffffff8ef7f800 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline] #0: ffffffff8ef7f800 (uuid_mutex){+.+.}-{4:4}, at: btrfs_get_tree+0x47c/0x1910 fs/btrfs/super.c:2121 #1: ffff8880265758d0 (&fs_devs->device_list_mutex){+.+.}-{4:4}, at: device_list_add+0x487/0x2280 fs/btrfs/volumes.c:843 stack backtrace: CPU: 0 UID: 0 PID: 10859 Comm: syz.4.1090 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 down_read+0x47/0x2e0 kernel/locking/rwsem.c:1568 inode_lock_shared include/linux/fs.h:1044 [inline] lookup_slow+0x46/0x70 fs/namei.c:1931 walk_component fs/namei.c:2278 [inline] lookup_last fs/namei.c:2785 [inline] path_lookupat+0x3f5/0x8c0 fs/namei.c:2809 filename_lookup+0x256/0x5d0 fs/namei.c:2838 kern_path+0x3d/0x150 fs/namei.c:3044 is_same_device fs/btrfs/volumes.c:764 [inline] device_list_add+0xfd1/0x2280 fs/btrfs/volumes.c:898 btrfs_scan_one_device+0x3ef/0x680 fs/btrfs/volumes.c:1499 btrfs_get_tree_super fs/btrfs/super.c:1858 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline] btrfs_get_tree+0x4ab/0x1910 fs/btrfs/super.c:2121 vfs_get_tree+0x92/0x2a0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3758 [inline] do_new_mount+0x341/0xd30 fs/namespace.c:3834 do_mount fs/namespace.c:4167 [inline] __do_sys_mount fs/namespace.c:4399 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4376 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f70b839da8a Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f70b921be58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f70b921bee0 RCX: 00007f70b839da8a RDX: 0000200000000200 RSI: 0000200000005600 RDI: 00007f70b921bea0 RBP: 0000200000000200 R08: 00007f70b921bee0 R09: 0000000000000800 R10: 0000000000000800 R11: 0000000000000246 R12: 0000200000005600 R13: 00007f70b921bea0 R14: 000000000000559e R15: 0000200000000240