[syzbot] [btrfs?] WARNING in __btrfs_free_extent (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 86987d84b968 Merge tag 'v6.11-rc5-client-fixes' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=109f1425980000
kernel config: https://syzkaller.appspot.com/x/.config?x=a0455552d0b27491
dashboard link: https://syzkaller.appspot.com/bug?extid=480676efc0c3a76b5214
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/87692913ef45/disk-86987d84.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a27da6973d7f/vmlinux-86987d84.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2e28d02ce725/bzImage-86987d84.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+480676...@syzkaller.appspotmail.com

------------[ cut here ]------------
BTRFS: Transaction aborted (error -2)
WARNING: CPU: 1 PID: 63 at fs/btrfs/extent-tree.c:2972 do_free_extent_accounting fs/btrfs/extent-tree.c:2972 [inline]
WARNING: CPU: 1 PID: 63 at fs/btrfs/extent-tree.c:2972 __btrfs_free_extent+0x32d1/0x3a10 fs/btrfs/extent-tree.c:3346
Modules linked in:
CPU: 1 UID: 0 PID: 63 Comm: kworker/u8:4 Not tainted 6.11.0-rc5-syzkaller-00057-g86987d84b968 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: events_unbound btrfs_async_reclaim_metadata_space
RIP: 0010:do_free_extent_accounting fs/btrfs/extent-tree.c:2972 [inline]
RIP: 0010:__btrfs_free_extent+0x32d1/0x3a10 fs/btrfs/extent-tree.c:3346
Code: e8 24 a4 ae fd 90 0f 0b 90 90 e9 3c f3 ff ff e8 35 80 ec fd 90 48 c7 c7 00 79 2b 8c 44 8b 6c 24 18 44 89 ee e8 00 a4 ae fd 90 <0f> 0b 90 90 4c 8b 24 24 e9 4f f3 ff ff e8 0d 80 ec fd 90 48 c7 c7
RSP: 0018:ffffc900015e6f80 EFLAGS: 00010246
RAX: ec2b4374561a8400 RBX: ffff88805d790001 RCX: ffff888015581e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900015e7150 R08: ffffffff8155b212 R09: fffffbfff1cba0e0
R10: dffffc0000000000 R11: fffffbfff1cba0e0 R12: dffffc0000000000
R13: 00000000fffffffe R14: 0000000000000000 R15: ffff88805d3be5c8
FS: 0000000000000000(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3dca9f0270 CR3: 000000002dd02000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
run_delayed_tree_ref fs/btrfs/extent-tree.c:1724 [inline]
run_one_delayed_ref fs/btrfs/extent-tree.c:1750 [inline]
btrfs_run_delayed_refs_for_head fs/btrfs/extent-tree.c:2015 [inline]
__btrfs_run_delayed_refs+0x112e/0x4680 fs/btrfs/extent-tree.c:2085
btrfs_run_delayed_refs+0xe3/0x2c0 fs/btrfs/extent-tree.c:2197
btrfs_commit_transaction+0x4be/0x3740 fs/btrfs/transaction.c:2198
flush_space+0x19c/0xd00 fs/btrfs/space-info.c:835
btrfs_async_reclaim_metadata_space+0x6dc/0x840 fs/btrfs/space-info.c:1106
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
worker_thread+0x86d/0xd10 kernel/workqueue.c:3389
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>


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[Qu Wenruo]

在 2024/9/1 03:29, syzbot 写道:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 86987d84b968 Merge tag 'v6.11-rc5-client-fixes' of git://g..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=109f1425980000

I was checking the console and trying to find out what's before the
transaction abort.

The error number means it's ENOENT thus it seems to be a missing extent
item or whatever.

But the console output contains not even the WARNING line, is the
console output trimmed or whatever?

Thanks,
Qu

[Aleksandr Nogikh]

On Sun, Sep 1, 2024 at 12:33 AM 'Qu Wenruo' via syzkaller-bugs
<syzkall...@googlegroups.com> wrote:
>
>
>
> 在 2024/9/1 03:29, syzbot 写道:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: 86987d84b968 Merge tag 'v6.11-rc5-client-fixes' of git://g..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=109f1425980000
>
> I was checking the console and trying to find out what's before the
> transaction abort.
>
> The error number means it's ENOENT thus it seems to be a missing extent
> item or whatever.
>
> But the console output contains not even the WARNING line, is the
> console output trimmed or whatever?

Yes, that output log was indeed too big and was just trimmed to fit in
the limits :/
I'll take a look into how we can handle it better on the syzbot side.

In the meanwhile, there are a few other console logs on the dashboard
[1] that were not trimmed and that contain the WARNING line. E.g.
https://syzkaller.appspot.com/text?tag=CrashLog&x=174d4215980000

[1] https://syzkaller.appspot.com/bug?extid=480676efc0c3a76b5214

--
Aleksandr

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 9551a26f17d9 Merge tag 'loongarch-6.19' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=104f1e1a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f315601b98a91c0b
dashboard link: https://syzkaller.appspot.com/bug?extid=480676efc0c3a76b5214
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=144f1e1a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1525f1c2580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b23c812ec291/disk-9551a26f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8b0564ab1672/vmlinux-9551a26f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b8aac5f6fcdb/bzImage-9551a26f.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/a5ef4ee7676b/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=11027592580000)
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/5770d00b6a18/mount_5.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=1125f1c2580000)
mounted in repro #3: https://storage.googleapis.com/syzbot-assets/3eefe4d56574/mount_9.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+480676...@syzkaller.appspotmail.com

BTRFS info (device loop0): trying to use backup root at mount time
BTRFS info (device loop0): force zstd compression, level 3
BTRFS info (device loop0): balance: start -d -m
BTRFS info (device loop0): relocating block group 6881280 flags data|metadata
BTRFS info (device loop0): relocating block group 5242880 flags data|metadata
------------[ cut here ]------------
BTRFS: Transaction aborted (error -28)
WARNING: fs/btrfs/extent-tree.c:3235 at 0x0, CPU#0: syz.0.22/6065
Modules linked in:
CPU: 0 UID: 0 PID: 6065 Comm: syz.0.22 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__btrfs_free_extent+0x1d84/0x3f40 fs/btrfs/extent-tree.c:3235
Code: ae 0b 00 00 e8 4d ef e3 fd 84 c0 0f 84 99 02 00 00 e8 80 16 fe fd e9 97 0b 00 00 e8 76 16 fe fd 48 8d 3d df 0f 21 0b 44 89 e6 <67> 48 0f b9 3a e9 87 e9 ff ff e8 2d dc 10 07 89 c3 31 ff 89 c6 e8
RSP: 0018:ffffc90003b66f40 EFLAGS: 00010293
RAX: ffffffff83c25bca RBX: 0000000000000000 RCX: ffff88802e535ac0
RDX: 0000000000000000 RSI: 00000000ffffffe4 RDI: ffffffff8ee36bb0
RBP: ffffc90003b670f0 R08: ffff88802e535ac0 R09: 0000000000000003
R10: 0000000000000100 R11: 00000000fffffffb R12: 00000000ffffffe4
R13: dffffc0000000000 R14: 00000000ffffffe4 R15: ffff888033d40001
FS: 00007f6ffbc8e6c0(0000) GS:ffff888126d06000(0000) knlGS:0000000000000000

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

CR2: 00007fcfb92bce9c CR3: 0000000028020000 CR4: 00000000003526f0
Call Trace:
<TASK>
run_one_delayed_ref fs/btrfs/extent-tree.c:-1 [inline]
btrfs_run_delayed_refs_for_head fs/btrfs/extent-tree.c:1973 [inline]
__btrfs_run_delayed_refs+0xe6a/0x3af0 fs/btrfs/extent-tree.c:2048
btrfs_run_delayed_refs+0xe6/0x3a0 fs/btrfs/extent-tree.c:2160
btrfs_commit_transaction+0x28b/0x3b10 fs/btrfs/transaction.c:2229
prepare_to_relocate+0x3a1/0x490 fs/btrfs/relocation.c:3479
relocate_block_group+0x132/0xd70 fs/btrfs/relocation.c:3504
btrfs_relocate_block_group+0x580/0xba0 fs/btrfs/relocation.c:3966
btrfs_relocate_chunk+0x12f/0x5d0 fs/btrfs/volumes.c:3424
__btrfs_balance+0x190e/0x24f0 fs/btrfs/volumes.c:4197
btrfs_balance+0xac2/0x11b0 fs/btrfs/volumes.c:4571
btrfs_ioctl_balance+0x3d6/0x610 fs/btrfs/ioctl.c:3525
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6ffc61f749
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:00007f6ffbc8e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6ffc875fa0 RCX: 00007f6ffc61f749
RDX: 0000200000000180 RSI: 00000000c4009420 RDI: 0000000000000004
RBP: 00007f6ffc6a3f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6ffc876038 R14: 00007f6ffc875fa0 R15: 00007ffc98ea0f28
</TASK>
----------------
Code disassembly (best guess):
0: ae scas %es:(%rdi),%al
1: 0b 00 or (%rax),%eax
3: 00 e8 add %ch,%al
5: 4d ef rex.WRB out %eax,(%dx)
7: e3 fd jrcxz 0x6
9: 84 c0 test %al,%al
b: 0f 84 99 02 00 00 je 0x2aa
11: e8 80 16 fe fd call 0xfdfe1696
16: e9 97 0b 00 00 jmp 0xbb2
1b: e8 76 16 fe fd call 0xfdfe1696
20: 48 8d 3d df 0f 21 0b lea 0xb210fdf(%rip),%rdi # 0xb211006
27: 44 89 e6 mov %r12d,%esi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: e9 87 e9 ff ff jmp 0xffffe9bb
34: e8 2d dc 10 07 call 0x710dc66
39: 89 c3 mov %eax,%ebx
3b: 31 ff xor %edi,%edi
3d: 89 c6 mov %eax,%esi
3f: e8 .byte 0xe8


---
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