BTRFS info (device loop4): trying to use backup root at mount time
btrfs: Deprecated parameter 'usebackuproot'
BTRFS warning: 'usebackuproot' is deprecated, use 'rescue=usebackuproot' instead
BTRFS warning (device loop4 state M): Skipping commit of aborted transaction.
------------[ cut here ]------------
BTRFS: Transaction aborted (error -28)
WARNING: fs/btrfs/transaction.c:2037 at cleanup_transaction fs/btrfs/transaction.c:2037 [inline], CPU#0: syz.4.517/8977
WARNING: fs/btrfs/transaction.c:2037 at btrfs_commit_transaction+0x30f7/0x3b10 fs/btrfs/transaction.c:2630, CPU#0: syz.4.517/8977
Modules linked in:
CPU: 0 UID: 0 PID: 8977 Comm: syz.4.517 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:cleanup_transaction fs/btrfs/transaction.c:2037 [inline]
RIP: 0010:btrfs_commit_transaction+0x30ff/0x3b10 fs/btrfs/transaction.c:2630
Code: e7 77 f9 fd eb 7d e8 50 6b df fd 84 c0 74 25 e8 d7 77 f9 fd eb 6d e8 d0 77 f9 fd 48 8d 3d 39 6f 1d 0b 44 8b 6c 24 38 44 89 ee <67> 48 0f b9 3a e9 24 f9 ff ff e8 d2 91 0b 07 89 c3 31 ff 89 c6 e8
RSP: 0018:ffffc9000c4ef780 EFLAGS: 00010283
RAX: ffffffff83c634b0 RBX: ffff88805fbfc001 RCX: 0000000000080000
RDX: ffffc9000e263000 RSI: 00000000ffffffe4 RDI: ffffffff8ee3a3f0
RBP: ffffc9000c4efac0 R08: ffff88802dd55ac0 R09: 0000000000000003
R10: 0000000000000100 R11: 00000000fffffffb R12: 1ffff1100beb95f9
R13: 00000000ffffffe4 R14: 0000000000000000 R15: ffff88805fbfc000
FS:  00007fdde84fe6c0(0000) GS:ffff888126cef000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3ca95f5000 CR3: 000000005c81a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 btrfs_set_free_space_cache_v1_active+0x71/0x420 fs/btrfs/free-space-cache.c:4156
 btrfs_remount_cleanup fs/btrfs/super.c:1295 [inline]
 btrfs_reconfigure+0x1bd4/0x2160 fs/btrfs/super.c:1574
 reconfigure_super+0x227/0x880 fs/super.c:1077
 do_remount fs/namespace.c:3264 [inline]
 path_mount+0xd29/0xff0 fs/namespace.c:4014
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x313/0x410 fs/namespace.c:4201
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fddea2a0eea
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fdde84fde68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fdde84fdef0 RCX: 00007fddea2a0eea
RDX: 0000200000000180 RSI: 0000200000000100 RDI: 0000000000000000
RBP: 0000200000000180 R08: 00007fdde84fdef0 R09: 00000000022520a2
R10: 00000000022520a2 R11: 0000000000000246 R12: 0000200000000100
R13: 00007fdde84fdeb0 R14: 0000000000000000 R15: 00002000000002c0
 </TASK>
----------------
Code disassembly (best guess):
   0:	e7 77                	out    %eax,$0x77
   2:	f9                   	stc
   3:	fd                   	std
   4:	eb 7d                	jmp    0x83
   6:	e8 50 6b df fd       	call   0xfddf6b5b
   b:	84 c0                	test   %al,%al
   d:	74 25                	je     0x34
   f:	e8 d7 77 f9 fd       	call   0xfdf977eb
  14:	eb 6d                	jmp    0x83
  16:	e8 d0 77 f9 fd       	call   0xfdf977eb
  1b:	48 8d 3d 39 6f 1d 0b 	lea    0xb1d6f39(%rip),%rdi        # 0xb1d6f5b
  22:	44 8b 6c 24 38       	mov    0x38(%rsp),%r13d
  27:	44 89 ee             	mov    %r13d,%esi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 24 f9 ff ff       	jmp    0xfffff958
  34:	e8 d2 91 0b 07       	call   0x70b920b
  39:	89 c3                	mov    %eax,%ebx
  3b:	31 ff                	xor    %edi,%edi
  3d:	89 c6                	mov    %eax,%esi
  3f:	e8                   	.byte 0xe8