BTRFS info (device loop0): clearing compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2) ====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc7-syzkaller-00144-gb1427432d3b6 #0 Not tainted ------------------------------------------------------ syz.0.94/6491 is trying to acquire lock: ffff88801c331918 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}, at: btrfs_quota_enable+0x2be/0x1d50 fs/btrfs/qgroup.c:1059 but task is already holding lock: ffff88801c3324f8 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x164/0xd70 fs/btrfs/transaction.c:320 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (btrfs_trans_num_extwriters){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 join_transaction+0x1a4/0xd70 fs/btrfs/transaction.c:321 start_transaction+0x6ae/0x1620 fs/btrfs/transaction.c:705 btrfs_rebuild_free_space_tree+0xb1/0x4e0 fs/btrfs/free-space-tree.c:1317 btrfs_start_pre_rw_mount+0xd76/0x1180 fs/btrfs/disk-io.c:3074 open_ctree+0x2075/0x2800 fs/btrfs/disk-io.c:3614 btrfs_fill_super+0x19d/0x2e0 fs/btrfs/super.c:976 btrfs_get_tree_super fs/btrfs/super.c:1901 [inline] btrfs_get_tree+0x107c/0x1620 fs/btrfs/super.c:2096 vfs_get_tree+0x92/0x2b0 fs/super.c:1759 fc_mount+0x1c/0xb0 fs/namespace.c:1289 btrfs_get_tree_subvol fs/btrfs/super.c:2054 [inline] btrfs_get_tree+0x67d/0x1620 fs/btrfs/super.c:2097 vfs_get_tree+0x92/0x2b0 fs/super.c:1759 do_new_mount+0x24a/0xa40 fs/namespace.c:3881 do_mount fs/namespace.c:4221 [inline] __do_sys_mount fs/namespace.c:4432 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4409 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (btrfs_trans_num_writers){++++}-{0:0}: reacquire_held_locks+0x127/0x1d0 kernel/locking/lockdep.c:5383 __lock_release kernel/locking/lockdep.c:5572 [inline] lock_release+0x1b4/0x3e0 kernel/locking/lockdep.c:5887 percpu_up_read include/linux/percpu-rwsem.h:100 [inline] __sb_end_write include/linux/fs.h:1778 [inline] sb_end_intwrite+0x26/0x1c0 include/linux/fs.h:1895 __btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1075 btrfs_dirty_inode+0x14c/0x190 fs/btrfs/inode.c:6150 inode_update_time fs/inode.c:2076 [inline] __file_update_time fs/inode.c:2305 [inline] file_update_time+0x344/0x490 fs/inode.c:2335 btrfs_page_mkwrite+0x634/0x16a0 fs/btrfs/file.c:1814 do_page_mkwrite+0x14a/0x310 mm/memory.c:3287 do_shared_fault mm/memory.c:5594 [inline] do_fault mm/memory.c:5656 [inline] do_pte_missing mm/memory.c:4160 [inline] handle_pte_fault mm/memory.c:5997 [inline] __handle_mm_fault+0x18d2/0x5380 mm/memory.c:6140 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1388 handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 -> #2 (sb_pagefaults#3){.+.+}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 percpu_down_read include/linux/percpu-rwsem.h:52 [inline] __sb_start_write include/linux/fs.h:1783 [inline] sb_start_pagefault include/linux/fs.h:1948 [inline] btrfs_page_mkwrite+0x3b2/0x16a0 fs/btrfs/file.c:1798 do_page_mkwrite+0x14a/0x310 mm/memory.c:3287 wp_page_shared mm/memory.c:3688 [inline] do_wp_page+0x2626/0x5790 mm/memory.c:3907 handle_pte_fault mm/memory.c:6013 [inline] __handle_mm_fault+0x1028/0x5380 mm/memory.c:6140 handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309 do_user_addr_fault+0x764/0x1390 arch/x86/mm/fault.c:1388 handle_page_fault arch/x86/mm/fault.c:1480 [inline] exc_page_fault+0x68/0x110 arch/x86/mm/fault.c:1538 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 filldir+0x2a7/0x690 fs/readdir.c:-1 dir_emit include/linux/fs.h:3861 [inline] kernfs_fop_readdir+0x537/0x870 fs/kernfs/dir.c:1907 iterate_dir+0x5ac/0x770 fs/readdir.c:108 __do_sys_getdents fs/readdir.c:322 [inline] __se_sys_getdents+0xe4/0x250 fs/readdir.c:308 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (&root->kernfs_rwsem){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577 kernfs_add_one+0x41/0x520 fs/kernfs/dir.c:791 kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1091 sysfs_create_dir_ns+0x123/0x280 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x59f/0xb40 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x125/0x190 lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x111/0x2b0 fs/btrfs/sysfs.c:2616 btrfs_quota_enable+0x278/0x1d50 fs/btrfs/qgroup.c:1030 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3676 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746 btrfs_quota_enable+0x2be/0x1d50 fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3676 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 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: &fs_info->qgroup_ioctl_lock --> btrfs_trans_num_writers --> btrfs_trans_num_extwriters Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(btrfs_trans_num_extwriters); lock(btrfs_trans_num_writers); lock(btrfs_trans_num_extwriters); lock(&fs_info->qgroup_ioctl_lock); *** DEADLOCK *** 5 locks held by syz.0.94/6491: #0: ffff88802ac8e420 (sb_writers#16){.+.+}-{0:0}, at: mnt_want_write_file+0x60/0x200 fs/namespace.c:600 #1: ffff88801c330bd0 (&fs_info->subvol_sem){+.+.}-{4:4}, at: btrfs_ioctl_quota_ctl+0x178/0x1c0 fs/btrfs/ioctl.c:3675 #2: ffff88802ac8e610 (sb_internal#2){.+.+}-{0:0}, at: btrfs_quota_enable+0x2b1/0x1d50 fs/btrfs/qgroup.c:1057 #3: ffff88801c3324d0 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0x164/0xd70 fs/btrfs/transaction.c:320 #4: ffff88801c3324f8 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x164/0xd70 fs/btrfs/transaction.c:320 stack backtrace: CPU: 1 UID: 0 PID: 6491 Comm: syz.0.94 Not tainted 6.15.0-rc7-syzkaller-00144-gb1427432d3b6 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2079 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909 __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 __mutex_lock_common kernel/locking/mutex.c:601 [inline] __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:746 btrfs_quota_enable+0x2be/0x1d50 fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3676 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f8773d8e969 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8774bba038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f8773fb5fa0 RCX: 00007f8773d8e969 RDX: 0000200000000580 RSI: 00000000c0109428 RDI: 0000000000000003 RBP: 00007f8773e10ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f8773fb5fa0 R15: 00007fff18df21a8