======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc1-syzkaller-00065-g3b07108ada81 #0 Not tainted
------------------------------------------------------
syz.8.247/7959 is trying to acquire lock:
ffff88802651a610 (sb_internal#5){.+.+}-{0:0}, at: btrfs_dirty_inode+0xa5/0x1a0 fs/btrfs/inode.c:6126

but task is already holding lock:
ffff888028956fe0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:146 [inline]
ffff888028956fe0 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x214/0x530 mm/util.c:577

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #5 (&mm->mmap_lock){++++}-{4:4}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       down_read_killable+0xcb/0xcb0 kernel/locking/rwsem.c:1547
       mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:193
       get_mmap_lock_carefully mm/memory.c:6355 [inline]
       lock_mm_and_find_vma+0x29c/0x2f0 mm/memory.c:6406
       do_user_addr_fault arch/x86/mm/fault.c:1360 [inline]
       handle_page_fault arch/x86/mm/fault.c:1480 [inline]
       exc_page_fault+0x1c1/0x920 arch/x86/mm/fault.c:1538
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
       user_access_begin arch/x86/include/asm/uaccess.h:-1 [inline]
       filldir+0x2aa/0x6a0 fs/readdir.c:286
       dir_emit include/linux/fs.h:3861 [inline]
       kernfs_fop_readdir+0x545/0x870 fs/kernfs/dir.c:1907
       iterate_dir+0x5a9/0x760 fs/readdir.c:108
       __do_sys_getdents fs/readdir.c:322 [inline]
       __se_sys_getdents+0x1ff/0x4e0 fs/readdir.c:308
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #4 (&root->kernfs_rwsem){++++}-{4:4}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       down_write+0x9c/0x220 kernel/locking/rwsem.c:1577
       kernfs_add_one+0x41/0x530 fs/kernfs/dir.c:791
       kernfs_create_dir_ns+0xd9/0x120 fs/kernfs/dir.c:1091
       sysfs_create_dir_ns+0x1a2/0x3f0 fs/sysfs/dir.c:59
       create_dir lib/kobject.c:73 [inline]
       kobject_add_internal+0x435/0x8d0 lib/kobject.c:240
       kobject_add_varg lib/kobject.c:374 [inline]
       kobject_init_and_add+0x126/0x190 lib/kobject.c:457
       btrfs_sysfs_add_qgroups+0x117/0x2f0 fs/btrfs/sysfs.c:2616
       btrfs_quota_enable+0x287/0x21a0 fs/btrfs/qgroup.c:1030
       btrfs_ioctl_quota_ctl+0x144/0x1c0 fs/btrfs/ioctl.c:3676
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       __mutex_lock_common kernel/locking/mutex.c:601 [inline]
       __mutex_lock+0x1a5/0x10c0 kernel/locking/mutex.c:746
       btrfs_quota_enable+0x2cb/0x21a0 fs/btrfs/qgroup.c:1059
       btrfs_ioctl_quota_ctl+0x144/0x1c0 fs/btrfs/ioctl.c:3676
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:892
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (btrfs_trans_num_extwriters){++++}-{0:0}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       join_transaction+0x1aa/0xe60 fs/btrfs/transaction.c:321
       start_transaction+0x770/0x16b0 fs/btrfs/transaction.c:705
       btrfs_rebuild_free_space_tree+0xb4/0x500 fs/btrfs/free-space-tree.c:1317
       btrfs_start_pre_rw_mount+0xef1/0x1310 fs/btrfs/disk-io.c:3074
       open_ctree+0x246c/0x2990 fs/btrfs/disk-io.c:3614
       btrfs_fill_super fs/btrfs/super.c:972 [inline]
       btrfs_get_tree_super fs/btrfs/super.c:1898 [inline]
       btrfs_get_tree+0x131c/0x19e0 fs/btrfs/super.c:2093
       vfs_get_tree+0x90/0x2b0 fs/super.c:1759
       fc_mount+0x1b/0xb0 fs/namespace.c:1293
       btrfs_get_tree_subvol fs/btrfs/super.c:2051 [inline]
       btrfs_get_tree+0x68a/0x19e0 fs/btrfs/super.c:2094
       vfs_get_tree+0x90/0x2b0 fs/super.c:1759
       do_new_mount+0x2cf/0xb70 fs/namespace.c:3879
       do_mount fs/namespace.c:4219 [inline]
       __do_sys_mount fs/namespace.c:4430 [inline]
       __se_sys_mount+0x38c/0x400 fs/namespace.c:4407
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (btrfs_trans_num_writers){++++}-{0:0}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       join_transaction+0x188/0xe60 fs/btrfs/transaction.c:320
       start_transaction+0x770/0x16b0 fs/btrfs/transaction.c:705
       btrfs_rebuild_free_space_tree+0xb4/0x500 fs/btrfs/free-space-tree.c:1317
       btrfs_start_pre_rw_mount+0xef1/0x1310 fs/btrfs/disk-io.c:3074
       open_ctree+0x246c/0x2990 fs/btrfs/disk-io.c:3614
       btrfs_fill_super fs/btrfs/super.c:972 [inline]
       btrfs_get_tree_super fs/btrfs/super.c:1898 [inline]
       btrfs_get_tree+0x131c/0x19e0 fs/btrfs/super.c:2093
       vfs_get_tree+0x90/0x2b0 fs/super.c:1759
       fc_mount+0x1b/0xb0 fs/namespace.c:1293
       btrfs_get_tree_subvol fs/btrfs/super.c:2051 [inline]
       btrfs_get_tree+0x68a/0x19e0 fs/btrfs/super.c:2094
       vfs_get_tree+0x90/0x2b0 fs/super.c:1759
       do_new_mount+0x2cf/0xb70 fs/namespace.c:3879
       do_mount fs/namespace.c:4219 [inline]
       __do_sys_mount fs/namespace.c:4430 [inline]
       __se_sys_mount+0x38c/0x400 fs/namespace.c:4407
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (sb_internal#5){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3166 [inline]
       check_prevs_add kernel/locking/lockdep.c:3285 [inline]
       validate_chain+0xa69/0x24e0 kernel/locking/lockdep.c:3909
       __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235
       lock_acquire+0x116/0x2f0 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_intwrite include/linux/fs.h:1966 [inline]
       start_transaction+0x58e/0x16b0 fs/btrfs/transaction.c:699
       btrfs_dirty_inode+0xa5/0x1a0 fs/btrfs/inode.c:6126
       inode_update_time fs/inode.c:2076 [inline]
       touch_atime+0x27d/0x690 fs/inode.c:2149
       file_accessed include/linux/fs.h:2599 [inline]
       btrfs_file_mmap+0xbd/0x120 fs/btrfs/file.c:1938
       call_mmap include/linux/fs.h:2243 [inline]
       mmap_file mm/internal.h:167 [inline]
       __mmap_new_file_vma mm/vma.c:2310 [inline]
       __mmap_new_vma mm/vma.c:2374 [inline]
       __mmap_region mm/vma.c:2476 [inline]
       mmap_region+0x241d/0x2ea0 mm/vma.c:2554
       do_mmap+0xd42/0x1420 mm/mmap.c:561
       vm_mmap_pgoff+0x2a2/0x530 mm/util.c:579
       ksys_mmap_pgoff+0x4ee/0x720 mm/mmap.c:607
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf3/0x230 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:
  sb_internal#5 --> &root->kernfs_rwsem --> &mm->mmap_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&mm->mmap_lock);
                               lock(&root->kernfs_rwsem);
                               lock(&mm->mmap_lock);
  rlock(sb_internal#5);

 *** DEADLOCK ***

2 locks held by syz.8.247/7959:
 #0: ffff888028956fe0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:146 [inline]
 #0: ffff888028956fe0 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x214/0x530 mm/util.c:577
 #1: ffff88802651a420 (sb_writers#17){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2599 [inline]
 #1: ffff88802651a420 (sb_writers#17){.+.+}-{0:0}, at: btrfs_file_mmap+0xbd/0x120 fs/btrfs/file.c:1938

stack backtrace:
CPU: 0 UID: 0 PID: 7959 Comm: syz.8.247 Not tainted 6.15.0-rc1-syzkaller-00065-g3b07108ada81 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2079
 check_noncircular+0x142/0x160 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+0xa69/0x24e0 kernel/locking/lockdep.c:3909
 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235
 lock_acquire+0x116/0x2f0 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_intwrite include/linux/fs.h:1966 [inline]
 start_transaction+0x58e/0x16b0 fs/btrfs/transaction.c:699
 btrfs_dirty_inode+0xa5/0x1a0 fs/btrfs/inode.c:6126
 inode_update_time fs/inode.c:2076 [inline]
 touch_atime+0x27d/0x690 fs/inode.c:2149
 file_accessed include/linux/fs.h:2599 [inline]
 btrfs_file_mmap+0xbd/0x120 fs/btrfs/file.c:1938
 call_mmap include/linux/fs.h:2243 [inline]
 mmap_file mm/internal.h:167 [inline]
 __mmap_new_file_vma mm/vma.c:2310 [inline]
 __mmap_new_vma mm/vma.c:2374 [inline]
 __mmap_region mm/vma.c:2476 [inline]
 mmap_region+0x241d/0x2ea0 mm/vma.c:2554
 do_mmap+0xd42/0x1420 mm/mmap.c:561
 vm_mmap_pgoff+0x2a2/0x530 mm/util.c:579
 ksys_mmap_pgoff+0x4ee/0x720 mm/mmap.c:607
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f07ee58d169
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:00007f07ef338038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f07ee7a5fa0 RCX: 00007f07ee58d169
RDX: 0000000000000002 RSI: 0000000000001000 RDI: 0000200000001000
RBP: 00007f07ee60e730 R08: 0000000000000006 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f07ee7a5fa0 R15: 00007ffcc3f00108
 </TASK>