linux-kernel - [syzbot] [btrfs?] WARNING in __btrfs_run_delayed

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Message-ID: <69354e91.a70a0220.38f243.004e.GAE@google.com>
Date: Sun, 07 Dec 2025 01:53:21 -0800
From: syzbot <syzbot+64c9efba06e7ad505aef@...kaller.appspotmail.com>
To: clm@...com, dsterba@...e.com, josef@...icpanda.com, 
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [btrfs?] WARNING in __btrfs_run_delayed_items (2)

Hello,

syzbot found the following issue on:

HEAD commit:    44fc84337b6e Merge tag 'arm64-upstream' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=113b1192580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e613d5a6bd72b912
dashboard link: https://syzkaller.appspot.com/bug?extid=64c9efba06e7ad505aef
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 (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-44fc8433.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/62d35c4f6e28/vmlinux-44fc8433.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b8d61aa183d4/bzImage-44fc8433.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+64c9efba06e7ad505aef@...kaller.appspotmail.com

BTRFS error (device loop0): allocation failed flags 4, wanted 4096 tree-log 0, relocation: 0
BTRFS info (device loop0): space_info DATA+METADATA (sub-group id 0) has -1544192 free, is full
BTRFS info (device loop0): space_info total=11534336, used=3231744, pinned=45056, reserved=8257536, may_use=1544192, readonly=0 zone_unusable=0
BTRFS info (device loop0): global_block_rsv: size 1441792 reserved 1441792
BTRFS info (device loop0): trans_block_rsv: size 0 reserved 0
BTRFS info (device loop0): chunk_block_rsv: size 0 reserved 0
BTRFS info (device loop0): delayed_block_rsv: size 98304 reserved 94208
BTRFS info (device loop0): delayed_refs_rsv: size 0 reserved 0
BTRFS info (device loop0): block group 5242880 has 1638400 bytes, 1593344 used 45056 pinned 0 reserved 0 delalloc 0 super 0 zone_unusable (0 bytes available) 
BTRFS info (device loop0): block group has cluster?: no
BTRFS info (device loop0): 0 free space entries at or bigger than 4096 bytes
BTRFS info (device loop0): block group 6881280 has 1638400 bytes, 1638400 used 0 pinned 0 reserved 0 delalloc 0 super 0 zone_unusable (0 bytes available) 
BTRFS info (device loop0): block group has cluster?: no
BTRFS info (device loop0): 0 free space entries at or bigger than 4096 bytes
BTRFS info (device loop0): block group 8519680 has 8257536 bytes, 0 used 0 pinned 0 reserved 0 delalloc 0 super 0 zone_unusable (8257536 bytes available) 
BTRFS critical (device loop0): entry offset 8519680, bytes 8257536, 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): 8257536 bytes available across all block groups
------------[ cut here ]------------
BTRFS: Transaction aborted (error -28)
WARNING: fs/btrfs/delayed-inode.c:1179 at 0x0, CPU#0: kworker/u4:24/4375
Modules linked in:
CPU: 0 UID: 0 PID: 4375 Comm: kworker/u4:24 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
Workqueue: events_unbound btrfs_async_reclaim_data_space
RIP: 0010:__btrfs_run_delayed_items+0x46c/0x540 fs/btrfs/delayed-inode.c:1179
Code: 85 f6 75 07 e8 d5 c4 da fd eb 7a e8 ee b4 c0 fd 84 c0 74 20 e8 c5 c4 da fd eb 6a e8 be c4 da fd 48 8d 3d 97 0f a3 0b 44 89 e6 <67> 48 0f b9 3a e9 da fe ff ff e8 75 1e 62 07 41 89 c6 31 ff 89 c6
RSP: 0018:ffffc9000e887470 EFLAGS: 00010293
RAX: ffffffff83e64972 RBX: ffff888053d72630 RCX: ffff888033358000
RDX: 0000000000000000 RSI: 00000000ffffffe4 RDI: ffffffff8f895910
RBP: 0000000000000000 R08: ffff888033358000 R09: 0000000000000003
R10: 00000000fffffffb R11: 0000000000000000 R12: 00000000ffffffe4
R13: ffff888053c953d0 R14: ffff888052b70001 R15: 1ffff1100a7ae4c6
FS:  0000000000000000(0000) GS:ffff88808d6b7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000037d000 CR3: 0000000042677000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 btrfs_commit_transaction+0x865/0x3950 fs/btrfs/transaction.c:2325
 flush_space+0x48b/0xcb0 fs/btrfs/space-info.c:888
 do_async_reclaim_data_space+0x2a6/0x520 fs/btrfs/space-info.c:1410
 btrfs_async_reclaim_data_space+0x41/0x90 fs/btrfs/space-info.c:1458
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
----------------
Code disassembly (best guess):
   0:	85 f6                	test   %esi,%esi
   2:	75 07                	jne    0xb
   4:	e8 d5 c4 da fd       	call   0xfddac4de
   9:	eb 7a                	jmp    0x85
   b:	e8 ee b4 c0 fd       	call   0xfdc0b4fe
  10:	84 c0                	test   %al,%al
  12:	74 20                	je     0x34
  14:	e8 c5 c4 da fd       	call   0xfddac4de
  19:	eb 6a                	jmp    0x85
  1b:	e8 be c4 da fd       	call   0xfddac4de
  20:	48 8d 3d 97 0f a3 0b 	lea    0xba30f97(%rip),%rdi        # 0xba30fbe
  27:	44 89 e6             	mov    %r12d,%esi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 da fe ff ff       	jmp    0xffffff0e
  34:	e8 75 1e 62 07       	call   0x7621eae
  39:	41 89 c6             	mov    %eax,%r14d
  3c:	31 ff                	xor    %edi,%edi
  3e:	89 c6                	mov    %eax,%esi


---
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