[v6.6] WARNING in btrfs_chunk_alloc (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4a243110dc88 Linux 6.6.114
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=10382d2f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=59b486de080dec668a26
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1950ac2cd960/disk-4a243110.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d7dccd93693b/vmlinux-4a243110.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6f93496e2b47/bzImage-4a243110.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+59b486...@syzkaller.appspotmail.com

------------[ cut here ]------------
BTRFS: Transaction aborted (error -28)
WARNING: CPU: 0 PID: 19578 at fs/btrfs/block-group.c:3947 do_chunk_alloc fs/btrfs/block-group.c:3947 [inline]
WARNING: CPU: 0 PID: 19578 at fs/btrfs/block-group.c:3947 btrfs_chunk_alloc+0xe42/0xfe0 fs/btrfs/block-group.c:4189
Modules linked in:
CPU: 0 PID: 19578 Comm: syz.3.4510 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:do_chunk_alloc fs/btrfs/block-group.c:3947 [inline]
RIP: 0010:btrfs_chunk_alloc+0xe42/0xfe0 fs/btrfs/block-group.c:4189
Code: c7 40 f7 ee 8a 89 ee e8 4c fc b7 fd 0f 0b 4c 89 fb e9 2f fe ff ff e8 cd 7e ed fd 48 c7 c7 40 f7 ee 8a 44 89 f6 e8 2e fc b7 fd <0f> 0b 4c 89 fb e9 7c fe ff ff e8 af 7e ed fd 48 c7 c7 40 f7 ee 8a
RSP: 0018:ffffc9000464efd0 EFLAGS: 00010246
RAX: a921f5f773095500 RBX: ffff88807ca30001 RCX: 0000000000080000
RDX: ffffc9000ebea000 RSI: 000000000003153a RDI: 000000000003153b
RBP: 0000000000000000 R08: ffffc9000464ebc7 R09: 1ffff920008c9d78
R10: dffffc0000000000 R11: fffff520008c9d79 R12: ffff8880317bb000
R13: dffffc0000000000 R14: ffffffffffffffe4 R15: ffff88807d3ac000
FS: 00007f3fd33796c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcd7b2e3a10 CR3: 0000000023eb8000 CR4: 00000000003506f0
Call Trace:
<TASK>
find_free_extent_update_loop fs/btrfs/extent-tree.c:4089 [inline]
find_free_extent+0x4d41/0x58a0 fs/btrfs/extent-tree.c:4487
btrfs_reserve_extent+0x2fb/0x660 fs/btrfs/extent-tree.c:4580
btrfs_alloc_tree_block+0x1ec/0x1310 fs/btrfs/extent-tree.c:4995
btrfs_force_cow_block+0x433/0x1b80 fs/btrfs/ctree.c:572
btrfs_cow_block+0x3cb/0x7e0 fs/btrfs/ctree.c:763
btrfs_search_slot+0xb43/0x27e0 fs/btrfs/ctree.c:-1
btrfs_insert_empty_items+0x9c/0x180 fs/btrfs/ctree.c:4467
btrfs_insert_empty_item fs/btrfs/ctree.h:649 [inline]
btrfs_insert_orphan_item+0x14d/0x1c0 fs/btrfs/orphan.c:25
btrfs_orphan_add+0x68/0x180 fs/btrfs/inode.c:3438
btrfs_unlink+0x276/0x340 fs/btrfs/inode.c:4219
vfs_unlink+0x389/0x600 fs/namei.c:4333
do_unlinkat+0x328/0x570 fs/namei.c:4399
__do_sys_unlinkat fs/namei.c:4442 [inline]
__se_sys_unlinkat fs/namei.c:4435 [inline]
__x64_sys_unlinkat+0xd5/0xe0 fs/namei.c:4435
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: 0033:0x7f3fd258efc9
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:00007f3fd3379038 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f3fd27e6090 RCX: 00007f3fd258efc9
RDX: 0000000000000000 RSI: 00002000000003c0 RDI: ffffffffffffff9c
RBP: 00007f3fd2611f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3fd27e6128 R14: 00007f3fd27e6090 R15: 00007ffc8b00e578
</TASK>


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 4a243110dc88 Linux 6.6.114
git tree: linux-6.6.y

console output: https://syzkaller.appspot.com/x/log.txt?x=1184ee7c580000

kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=59b486de080dec668a26
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13d14be2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17191d42580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1950ac2cd960/disk-4a243110.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d7dccd93693b/vmlinux-4a243110.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6f93496e2b47/bzImage-4a243110.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/15e42367e6cc/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=140b2f34580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+59b486...@syzkaller.appspotmail.com

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

WARNING: CPU: 0 PID: 42 at fs/btrfs/block-group.c:3947 do_chunk_alloc fs/btrfs/block-group.c:3947 [inline]
WARNING: CPU: 0 PID: 42 at fs/btrfs/block-group.c:3947 btrfs_chunk_alloc+0xe42/0xfe0 fs/btrfs/block-group.c:4189
Modules linked in:
CPU: 0 PID: 42 Comm: kworker/u4:2 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025

Workqueue: events_unbound btrfs_async_reclaim_data_space

RIP: 0010:do_chunk_alloc fs/btrfs/block-group.c:3947 [inline]
RIP: 0010:btrfs_chunk_alloc+0xe42/0xfe0 fs/btrfs/block-group.c:4189
Code: c7 40 f7 ee 8a 89 ee e8 4c fc b7 fd 0f 0b 4c 89 fb e9 2f fe ff ff e8 cd 7e ed fd 48 c7 c7 40 f7 ee 8a 44 89 f6 e8 2e fc b7 fd <0f> 0b 4c 89 fb e9 7c fe ff ff e8 af 7e ed fd 48 c7 c7 40 f7 ee 8a

RSP: 0018:ffffc90000b37918 EFLAGS: 00010246
RAX: 7850eb74c2146200 RBX: ffff88805ea44001 RCX: ffff8880192a9e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: 0000000000000000 R08: ffffc90000b37527 R09: 1ffff92000166ea4
R10: dffffc0000000000 R11: fffff52000166ea5 R12: ffff888023a66800
R13: dffffc0000000000 R14: ffffffffffffffe4 R15: ffff88806e308800
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000

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

CR2: 0000200000717000 CR3: 000000000cb30000 CR4: 00000000003506f0
Call Trace:
<TASK>
flush_space+0x516/0xd10 fs/btrfs/space-info.c:764
btrfs_async_reclaim_data_space+0x12a/0x530 fs/btrfs/space-info.c:1283
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>


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