Re: [syzbot] [btrfs?] kernel BUG in btrfs_qgroup_inherit

[syzbot <syzbot+b44d4a4885bc82af2a06@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in btrfs_space_info_update_bytes_may_use

BTRFS info (device loop0): last unmount of filesystem 395ef67a-297e-477c-816d-cd80a5b93e5d
------------[ cut here ]------------
WARNING: fs/btrfs/space-info.h:257 at btrfs_space_info_update_bytes_may_use+0x318/0x600 fs/btrfs/space-info.h:257, CPU#0: syz-executor/5723
Modules linked in:
CPU: 0 UID: 0 PID: 5723 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:btrfs_space_info_update_bytes_may_use+0x318/0x600 fs/btrfs/space-info.h:257
Code: 00 00 74 08 4c 89 ff e8 56 d6 32 fe 4d 8b 27 4c 89 e7 48 8b 6c 24 18 48 89 ee e8 73 fc ca fd 49 39 ec 73 1c e8 09 fa ca fd 90 <0f> 0b 90 31 db 43 80 7c 35 00 00 0f 85 48 ff ff ff e9 4b ff ff ff
RSP: 0018:ffffc900029ff9d0 EFLAGS: 00010293
RAX: ffffffff83f6c687 RBX: ffffffffffea0000 RCX: ffff888043438000
RDX: 0000000000000000 RSI: 0000000000160000 RDI: 000000000015f000
RBP: 0000000000160000 R08: ffffffff8fa19777 R09: 1ffffffff1f432ee
R10: dffffc0000000000 R11: fffffbfff1f432ef R12: 000000000015f000
R13: 1ffff11007879710 R14: dffffc0000000000 R15: ffff88803c3cb880
FS:  000055558d353500(0000) GS:ffff88808d239000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff9fad9d38 CR3: 0000000041c16000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 btrfs_space_info_free_bytes_may_use fs/btrfs/space-info.h:294 [inline]
 block_rsv_release_bytes fs/btrfs/block-rsv.c:153 [inline]
 btrfs_block_rsv_release+0x462/0x570 fs/btrfs/block-rsv.c:290
 btrfs_release_global_block_rsv+0x33/0x270 fs/btrfs/block-rsv.c:455
 btrfs_free_block_groups+0xcbf/0xfd0 fs/btrfs/block-group.c:4579
 close_ctree+0x7bc/0x1380 fs/btrfs/disk-io.c:4410
 generic_shutdown_super+0x135/0x2c0 fs/super.c:643
 kill_anon_super+0x3b/0x70 fs/super.c:1289
 btrfs_kill_super+0x41/0x50 fs/btrfs/super.c:2129
 deactivate_locked_super+0xbc/0x130 fs/super.c:474
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1318
 task_work_run+0x1d4/0x260 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0xff/0x4f0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x2e3/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3cbc790af7
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fff9fada4e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f3cbc813d7d RCX: 00007f3cbc790af7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff9fada5a0
RBP: 00007fff9fada5a0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007fff9fadb630
R13: 00007f3cbc813d7d R14: 0000000000026b03 R15: 00007fff9fadb670
 </TASK>


Tested on:

commit:         c2f2b01b Merge tag 'i3c/for-6.19' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14fd321a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1889d7812b50029c
dashboard link: https://syzkaller.appspot.com/bug?extid=b44d4a4885bc82af2a06
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=173be992580000