[syzbot] [btrfs?] WARNING in btrfs_put_transaction (5)

[syzbot] [btrfs?] WARNING in btrfs_put_transaction (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    b69053dd3ffb wifi: mt76: Remove blank line after mt792x fi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=137c3fb4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a94030c847137a18
dashboard link: https://syzkaller.appspot.com/bug?extid=6d30e046bbd449d3f6f1
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/18036fd3b399/disk-b69053dd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/bcf4c5ec9d8e/vmlinux-b69053dd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b4101a9d1eed/bzImage-b69053dd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6d30e046bbd449d3f6f1@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: fs/btrfs/transaction.c:145 at btrfs_put_transaction+0x52d/0x560 fs/btrfs/transaction.c:145, CPU#0: btrfs-transacti/1033
Modules linked in:
CPU: 0 UID: 0 PID: 1033 Comm: btrfs-transacti Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:btrfs_put_transaction+0x52d/0x560 fs/btrfs/transaction.c:145
Code: 07 fc ff ff e8 94 2a f1 fd 4c 89 f7 be 03 00 00 00 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d e9 b9 1b be 00 e8 74 2a f1 fd 90 <0f> 0b 90 e9 6f fb ff ff e8 66 2a f1 fd 90 0f 0b 90 e9 8c fb ff ff
RSP: 0018:ffffc900052e7970 EFLAGS: 00010293
RAX: ffffffff83cfcd4c RBX: ffff8880a4cba000 RCX: ffff888034bf3d00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
RBP: dffffc0000000000 R08: ffff8880a4cba013 R09: 1ffff11014997402
R10: dffffc0000000000 R11: ffffed1014997403 R12: ffff8880a4cba000
R13: 0000000000000000 R14: ffff8880a4cba358 R15: ffff88803251cc88
FS:  0000000000000000(0000) GS:ffff888125e1f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffde9f8b92c CR3: 000000000dd3a000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 btrfs_commit_transaction+0x22cf/0x3b10 fs/btrfs/transaction.c:2598
 transaction_kthread+0x2b1/0x450 fs/btrfs/disk-io.c:1587
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>


---
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Re: [syzbot] [btrfs?] WARNING in btrfs_put_transaction (5)

[David Sterba]

On Mon, Jan 05, 2026 at 05:02:21PM -0800, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    b69053dd3ffb wifi: mt76: Remove blank line after mt792x fi..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=137c3fb4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a94030c847137a18
> dashboard link: https://syzkaller.appspot.com/bug?extid=6d30e046bbd449d3f6f1
> 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/18036fd3b399/disk-b69053dd.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/bcf4c5ec9d8e/vmlinux-b69053dd.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/b4101a9d1eed/bzImage-b69053dd.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+6d30e046bbd449d3f6f1@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> WARNING: fs/btrfs/transaction.c:145 at btrfs_put_transaction+0x52d/0x560 fs/btrfs/transaction.c:145, CPU#0: btrfs-transacti/1033

 141 void btrfs_put_transaction(struct btrfs_transaction *transaction)
 142 {
 143         if (refcount_dec_and_test(&transaction->use_count)) {
 144                 BUG_ON(!list_empty(&transaction->list));
 145                 WARN_ON(!xa_empty(&transaction->delayed_refs.head_refs));

> Modules linked in:
> CPU: 0 UID: 0 PID: 1033 Comm: btrfs-transacti Tainted: G             L      syzkaller #0 PREEMPT(full) 
> Tainted: [L]=SOFTLOCKUP
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
> RIP: 0010:btrfs_put_transaction+0x52d/0x560 fs/btrfs/transaction.c:145
> Code: 07 fc ff ff e8 94 2a f1 fd 4c 89 f7 be 03 00 00 00 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d e9 b9 1b be 00 e8 74 2a f1 fd 90 <0f> 0b 90 e9 6f fb ff ff e8 66 2a f1 fd 90 0f 0b 90 e9 8c fb ff ff
> RSP: 0018:ffffc900052e7970 EFLAGS: 00010293
> RAX: ffffffff83cfcd4c RBX: ffff8880a4cba000 RCX: ffff888034bf3d00
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000001
> RBP: dffffc0000000000 R08: ffff8880a4cba013 R09: 1ffff11014997402
> R10: dffffc0000000000 R11: ffffed1014997403 R12: ffff8880a4cba000
> R13: 0000000000000000 R14: ffff8880a4cba358 R15: ffff88803251cc88
> FS:  0000000000000000(0000) GS:ffff888125e1f000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ffde9f8b92c CR3: 000000000dd3a000 CR4: 0000000000350ef0
> Call Trace:
>  <TASK>
>  btrfs_commit_transaction+0x22cf/0x3b10 fs/btrfs/transaction.c:2598
>  transaction_kthread+0x2b1/0x450 fs/btrfs/disk-io.c:1587
>  kthread+0x711/0x8a0 kernel/kthread.c:463
>  ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
>  </TASK>