[v6.6] WARNING in btrfs_create_pending_block_groups

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15dc83d4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=c14787f64c14bb933980
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c14787...@syzkaller.appspotmail.com

BTRFS info (device loop6): balance: start -susage=34359738372,drange=7..526332,limit=0..6
------------[ cut here ]------------
BTRFS: Transaction aborted (error -28)
WARNING: CPU: 0 PID: 9155 at fs/btrfs/block-group.c:2753 btrfs_create_pending_block_groups+0xe10/0xf20 fs/btrfs/block-group.c:2753
Modules linked in:
CPU: 0 PID: 9155 Comm: syz.6.591 Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:btrfs_create_pending_block_groups+0xe10/0xf20 fs/btrfs/block-group.c:2753
Code: 51 9a 6a 8c ba c8 0a 00 00 44 89 e1 e8 29 c1 c4 06 e9 19 f6 ff ff e8 5f 4b ed fd 48 c7 c7 c0 fc ee 8a 44 89 e6 e8 50 b0 b7 fd <0f> 0b e9 79 fe ff ff e8 44 4b ed fd 48 c7 c7 c0 fc ee 8a 44 89 ee
RSP: 0018:ffffc900034b7740 EFLAGS: 00010246
RAX: ba61cd671fa0d300 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000c499000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: ffffc900034b7988 R08: ffff8880b8e28c13 R09: 1ffff110171c5182
R10: dffffc0000000000 R11: ffffed10171c5183 R12: 00000000ffffffe4
R13: ffff88802fc02850 R14: ffff88802fc02858 R15: ffff88802d7b0001
FS: 00007f5e9e7ee6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000006a785000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__btrfs_end_transaction+0x140/0x630 fs/btrfs/transaction.c:1023
btrfs_inc_block_group_ro+0x596/0x630 fs/btrfs/block-group.c:3014
btrfs_relocate_block_group+0x452/0xd70 fs/btrfs/relocation.c:4013
btrfs_relocate_chunk+0x12a/0x3b0 fs/btrfs/volumes.c:3315
__btrfs_balance+0x187b/0x21c0 fs/btrfs/volumes.c:4061
btrfs_balance+0xcb1/0x11c0 fs/btrfs/volumes.c:4438
btrfs_ioctl_balance+0x4a2/0x730 fs/btrfs/ioctl.c:3647
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5e9d98e929
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:00007f5e9e7ee038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5e9dbb5fa0 RCX: 00007f5e9d98e929
RDX: 0000200000000440 RSI: 00000000c4009420 RDI: 0000000000000003
RBP: 00007f5e9da10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f5e9dbb5fa0 R15: 00007ffea11cf2f8
</TASK>


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 3f5b4c104b7d Linux 6.6.95
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15bed3d4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b80883c3ded77c16

dashboard link: https://syzkaller.appspot.com/bug?extid=c14787f64c14bb933980
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=161a848c580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15493770580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0efd4e01816e/disk-3f5b4c10.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f7c9d20858cc/vmlinux-3f5b4c10.xz
kernel image: https://storage.googleapis.com/syzbot-assets/18f8dc74ef68/bzImage-3f5b4c10.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d8d0e63ee445/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=153ab48c580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c14787...@syzkaller.appspotmail.com

BTRFS critical (device loop0): entry offset 6881280, bytes 1638400, bitmap no
BTRFS info (device loop0): block group has cluster?: no
BTRFS info (device loop0): 1 free space entries at or bigger than 4096 bytes
BTRFS info (device loop0): 3215360 bytes available across all block groups

------------[ cut here ]------------
BTRFS: Transaction aborted (error -28)

WARNING: CPU: 1 PID: 5924 at fs/btrfs/block-group.c:2753 btrfs_create_pending_block_groups+0xe10/0xf20 fs/btrfs/block-group.c:2753
Modules linked in:
CPU: 1 PID: 5924 Comm: syz.0.16 Not tainted 6.6.95-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:btrfs_create_pending_block_groups+0xe10/0xf20 fs/btrfs/block-group.c:2753

Code: ba a7 6a 8c ba c8 0a 00 00 44 89 e1 e8 d9 e2 c4 06 e9 19 f6 ff ff e8 9f 3d ed fd 48 c7 c7 80 fd ee 8a 44 89 e6 e8 00 a2 b7 fd <0f> 0b e9 79 fe ff ff e8 84 3d ed fd 48 c7 c7 80 fd ee 8a 44 89 ee
RSP: 0018:ffffc90003357740 EFLAGS: 00010246
RAX: 3ea5fb7586894400 RBX: 0000000000000000 RCX: ffff888076559e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: ffffc90003357988 R08: ffffc90003357347 R09: 1ffff9200066ae68
R10: dffffc0000000000 R11: fffff5200066ae69 R12: 00000000ffffffe4
R13: ffff88807833e850 R14: ffff88807833e858 R15: ffff88802f7a0001
FS: 000055555b16f500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007ffcc38bac34 CR3: 0000000075438000 CR4: 00000000003506e0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__btrfs_end_transaction+0x140/0x630 fs/btrfs/transaction.c:1023
btrfs_inc_block_group_ro+0x596/0x630 fs/btrfs/block-group.c:3014
btrfs_relocate_block_group+0x452/0xd70 fs/btrfs/relocation.c:4013
btrfs_relocate_chunk+0x12a/0x3b0 fs/btrfs/volumes.c:3315
__btrfs_balance+0x187b/0x21c0 fs/btrfs/volumes.c:4061
btrfs_balance+0xcb1/0x11c0 fs/btrfs/volumes.c:4438
btrfs_ioctl_balance+0x4a2/0x730 fs/btrfs/ioctl.c:3647
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2

RIP: 0033:0x7f331438e929

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:00007ffd866b2928 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f33145b5fa0 RCX: 00007f331438e929

RDX: 0000200000000440 RSI: 00000000c4009420 RDI: 0000000000000003

RBP: 00007f3314410b39 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007f33145b5fa0 R14: 00007f33145b5fa0 R15: 0000000000000003
</TASK>


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