BTRFS info (device loop1): first mount of filesystem 395ef67a-297e-477c-816d-cd80a5b93e5d BTRFS info (device loop1): using sha256 (sha256-x86_64) checksum algorithm BTRFS info (device loop1): using free-space-tree BTRFS info (device loop1): rebuilding free space tree ====================================================== WARNING: possible circular locking dependency detected 6.16.0-rc1-syzkaller #0 Not tainted ------------------------------------------------------ syz.1.217/7432 is trying to acquire lock: ffff88806042d988 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}, at: btrfs_quota_enable+0x2be/0x1d50 fs/btrfs/qgroup.c:1059 but task is already holding lock: ffff88806042e530 (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:5871 join_transaction+0x1a4/0xd70 fs/btrfs/transaction.c:321 start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705 btrfs_rebuild_free_space_tree+0xb1/0x4e0 fs/btrfs/free-space-tree.c:1333 btrfs_start_pre_rw_mount+0xd76/0x1180 fs/btrfs/disk-io.c:3077 open_ctree+0x2078/0x2800 fs/btrfs/disk-io.c:3617 btrfs_fill_super+0x19d/0x2e0 fs/btrfs/super.c:968 btrfs_get_tree_super fs/btrfs/super.c:1893 [inline] btrfs_get_tree+0x107c/0x1630 fs/btrfs/super.c:2088 vfs_get_tree+0x92/0x2b0 fs/super.c:1802 fc_mount+0x1c/0xb0 fs/namespace.c:1290 btrfs_get_tree_subvol fs/btrfs/super.c:2046 [inline] btrfs_get_tree+0x67d/0x1630 fs/btrfs/super.c:2089 vfs_get_tree+0x92/0x2b0 fs/super.c:1802 do_new_mount+0x24a/0xa40 fs/namespace.c:3885 do_mount fs/namespace.c:4222 [inline] __do_sys_mount fs/namespace.c:4433 [inline] __se_sys_mount+0x317/0x410 fs/namespace.c:4410 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 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:5388 __lock_release kernel/locking/lockdep.c:5577 [inline] lock_release+0x1b4/0x3e0 kernel/locking/lockdep.c:5892 percpu_up_read include/linux/percpu-rwsem.h:112 [inline] __sb_end_write include/linux/fs.h:1788 [inline] sb_end_intwrite+0x26/0x1c0 include/linux/fs.h:1905 __btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1076 btrfs_dirty_inode+0x14c/0x190 fs/btrfs/inode.c:6239 inode_update_time fs/inode.c:2076 [inline] touch_atime+0x2f6/0x6d0 fs/inode.c:2149 file_accessed include/linux/fs.h:2648 [inline] btrfs_file_mmap+0xbb/0x120 fs/btrfs/file.c:1988 call_mmap include/linux/fs.h:2282 [inline] mmap_file mm/internal.h:167 [inline] __mmap_new_file_vma mm/vma.c:2419 [inline] __mmap_new_vma mm/vma.c:2481 [inline] __mmap_region mm/vma.c:2636 [inline] mmap_region+0x1224/0x1f30 mm/vma.c:2706 do_mmap+0xc45/0x10d0 mm/mmap.c:561 vm_mmap_pgoff+0x31b/0x4c0 mm/util.c:579 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:607 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (&mm->mmap_lock){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 down_read_killable+0x50/0x350 kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:421 get_mmap_lock_carefully mm/mmap_lock.c:197 [inline] lock_mm_and_find_vma+0x2a8/0x300 mm/mmap_lock.c:248 do_user_addr_fault+0x331/0x1390 arch/x86/mm/fault.c:1359 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 filldir64+0x2c7/0x690 fs/readdir.c:-1 dir_emit include/linux/fs.h:3915 [inline] kernfs_fop_readdir+0x537/0x870 fs/kernfs/dir.c:1910 iterate_dir+0x5af/0x770 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:410 [inline] __se_sys_getdents64+0xe4/0x260 fs/readdir.c:396 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 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:5871 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:1093 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:2635 btrfs_quota_enable+0x278/0x1d50 fs/btrfs/qgroup.c:1030 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 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:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:747 btrfs_quota_enable+0x2be/0x1d50 fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 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.1.217/7432: #0: ffff888056398428 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write_file+0x60/0x200 fs/namespace.c:601 #1: ffff88806042cc40 (&fs_info->subvol_sem){+.+.}-{4:4}, at: btrfs_ioctl_quota_ctl+0x178/0x1c0 fs/btrfs/ioctl.c:3672 #2: ffff888056398618 (sb_internal#2){.+.+}-{0:0}, at: btrfs_quota_enable+0x2b1/0x1d50 fs/btrfs/qgroup.c:1057 #3: ffff88806042e508 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0x164/0xd70 fs/btrfs/transaction.c:320 #4: ffff88806042e530 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x164/0xd70 fs/btrfs/transaction.c:320 stack backtrace: CPU: 1 UID: 0 PID: 7432 Comm: syz.1.217 Not tainted 6.16.0-rc1-syzkaller #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:2046 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3168 [inline] check_prevs_add kernel/locking/lockdep.c:3287 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 __mutex_lock_common kernel/locking/mutex.c:602 [inline] __mutex_lock+0x182/0xe80 kernel/locking/mutex.c:747 btrfs_quota_enable+0x2be/0x1d50 fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3673 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:907 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7efea878e929 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:00007efea9532038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007efea89b5fa0 RCX: 00007efea878e929 RDX: 00002000000000c0 RSI: 00000000c0109428 RDI: 0000000000000003 RBP: 00007efea8810b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007efea89b5fa0 R15: 00007ffd4cb31d58