[syzbot] [btrfs?] WARNING in lookup_inline_extent_backref (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dbfc6422a34d Merge tag 'x86_urgent_for_v6.18_rc3' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11d993cd980000
kernel config: https://syzkaller.appspot.com/x/.config?x=25811b07889c90db
dashboard link: https://syzkaller.appspot.com/bug?extid=b0e66d3779134f468156
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-dbfc6422.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/73c799811c6a/vmlinux-dbfc6422.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e1bb4619e00f/bzImage-dbfc6422.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0e66d...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 5319 at fs/btrfs/extent-tree.c:836 lookup_inline_extent_backref+0x12c7/0x17f0 fs/btrfs/extent-tree.c:836
Modules linked in:
CPU: 0 UID: 0 PID: 5319 Comm: syz.0.0 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
RIP: 0010:lookup_inline_extent_backref+0x12c7/0x17f0 fs/btrfs/extent-tree.c:836
Code: 05 fe 26 a5 0e 48 3b 84 24 e0 01 00 00 0f 85 8e 04 00 00 89 d8 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d e9 5b 4b 81 07 cc 90 <0f> 0b 90 48 8b 44 24 78 42 80 3c 30 00 74 0a 48 8b 7c 24 20 e8 90
RSP: 0000:ffffc9000d23e820 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff888000784900 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000d23ea48 R08: 0000000000000000 R09: 1ffffd40002891c8
R10: dffffc0000000000 R11: fffff940002891c9 R12: 1ffff1100a23a242
R13: 00000000000000b2 R14: dffffc0000000000 R15: ffff8880110e2000
FS: 00007f1616ed56c0(0000) GS:ffff88808d733000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7e2ed37000 CR3: 000000003f2e0000 CR4: 0000000000352ef0
Call Trace:
<TASK>
insert_inline_extent_backref+0xa8/0x2f0 fs/btrfs/extent-tree.c:1205
__btrfs_inc_extent_ref+0x263/0x9e0 fs/btrfs/extent-tree.c:1503
run_one_delayed_ref fs/btrfs/extent-tree.c:-1 [inline]
btrfs_run_delayed_refs_for_head fs/btrfs/extent-tree.c:1972 [inline]
__btrfs_run_delayed_refs+0xebd/0x4130 fs/btrfs/extent-tree.c:2047
btrfs_run_delayed_refs+0xe6/0x3b0 fs/btrfs/extent-tree.c:2159
btrfs_start_dirty_block_groups+0xd3d/0x10a0 fs/btrfs/block-group.c:3534
btrfs_commit_transaction+0x674/0x3950 fs/btrfs/transaction.c:2241
btrfs_sync_file+0xd30/0x1160 fs/btrfs/file.c:1818
generic_write_sync include/linux/fs.h:3046 [inline]
btrfs_do_write_iter+0x59a/0x710 fs/btrfs/file.c:1469
iter_file_splice_write+0x975/0x10e0 fs/splice.c:738
do_splice_from fs/splice.c:938 [inline]
direct_splice_actor+0x101/0x160 fs/splice.c:1161
splice_direct_to_actor+0x5a8/0xcc0 fs/splice.c:1105
do_splice_direct_actor fs/splice.c:1204 [inline]
do_splice_direct+0x181/0x270 fs/splice.c:1230
do_sendfile+0x4da/0x7e0 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64+0x13e/0x190 fs/read_write.c:1417
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1615f8efc9
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:00007f1616ed5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f16161e6090 RCX: 00007f1615f8efc9
RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000008
RBP: 00007f1616011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 000000007ffff000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f16161e6128 R14: 00007f16161e6090 R15: 00007fff32122a28
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Qu Wenruo]

在 2025/10/27 19:35, syzbot 写道:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: dbfc6422a34d Merge tag 'x86_urgent_for_v6.18_rc3' of git:/..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11d993cd980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=25811b07889c90db
> dashboard link: https://syzkaller.appspot.com/bug?extid=b0e66d3779134f468156
> 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-dbfc6422.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/73c799811c6a/vmlinux-dbfc6422.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/e1bb4619e00f/bzImage-dbfc6422.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b0e66d...@syzkaller.appspotmail.com

This one is injecting an -ENOMEM at a critical path, which makes btrfs
to abort the current transaction.

To be honest, syzbot should not expect a completely quite system for
such injected error.

Thanks,
Qu

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: d79526b89571 Merge tag 'spi-fix-v7.0-merge-window' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11211fb2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=65722f41f7edc17e
dashboard link: https://syzkaller.appspot.com/bug?extid=b0e66d3779134f468156
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11a469e6580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16deeeaa580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-d79526b8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/49624ca295fd/vmlinux-d79526b8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b6bf3fe0601b/bzImage-d79526b8.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/bdd2b04fef16/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=11b2d95a580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b0e66d...@syzkaller.appspotmail.com

------------[ cut here ]------------

ret
WARNING: fs/btrfs/extent-tree.c:837 at lookup_inline_extent_backref+0x143e/0x1980 fs/btrfs/extent-tree.c:837, CPU#0: syz.0.51/6188
Modules linked in:
CPU: 0 UID: 0 PID: 6188 Comm: syz.0.51 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:lookup_inline_extent_backref+0x143e/0x1980 fs/btrfs/extent-tree.c:837
Code: d8 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d e9 48 80 cb 07 cc e8 52 e3 de fd bb fe ff ff ff 4c 8b 74 24 50 e9 af fe ff ff 90 <0f> 0b 90 48 8b 84 24 88 00 00 00 48 b9 00 00 00 00 00 fc ff df 80
RSP: 0018:ffffc9000f436dc0 EFLAGS: 00010202

RAX: 0000000000000001 RBX: 0000000000000001 RCX: 0000000000000000

RDX: ffff88803cfb0000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000f436fe8 R08: 0000000000000000 R09: 1ffffd40002a7c88
R10: dffffc0000000000 R11: fffff940002a7c89 R12: 0000000000530000
R13: ffff888012fe3dc0 R14: 0000000000000009 R15: ffff888040dba000
FS: 00007f51785dd6c0(0000) GS:ffff88808ca5b000(0000) knlGS:0000000000000000

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

CR2: 00007f51790e02c0 CR3: 0000000042618000 CR4: 0000000000352ef0
Call Trace:
<TASK>
insert_inline_extent_backref+0xa8/0x300 fs/btrfs/extent-tree.c:1206
__btrfs_inc_extent_ref+0x271/0xa00 fs/btrfs/extent-tree.c:1505
run_delayed_tree_ref fs/btrfs/extent-tree.c:1771 [inline]
run_one_delayed_ref fs/btrfs/extent-tree.c:1803 [inline]
btrfs_run_delayed_refs_for_head fs/btrfs/extent-tree.c:2003 [inline]
__btrfs_run_delayed_refs+0xf93/0x4240 fs/btrfs/extent-tree.c:2078
btrfs_run_delayed_refs+0xe6/0x3b0 fs/btrfs/extent-tree.c:2190
qgroup_account_snapshot fs/btrfs/transaction.c:1589 [inline]
create_pending_snapshot+0x1141/0x3ac0 fs/btrfs/transaction.c:1872
create_pending_snapshots+0x17c/0x1c0 fs/btrfs/transaction.c:1942
btrfs_commit_transaction+0xf75/0x31a0 fs/btrfs/transaction.c:2439
create_snapshot fs/btrfs/ioctl.c:779 [inline]
btrfs_mksubvol+0x9bc/0x10a0 fs/btrfs/ioctl.c:857
btrfs_mksnapshot+0xab/0xf0 fs/btrfs/ioctl.c:899
__btrfs_ioctl_snap_create+0x52e/0x750 fs/btrfs/ioctl.c:1163
btrfs_ioctl_snap_create_v2+0x1f8/0x3b0 fs/btrfs/ioctl.c:1242
btrfs_ioctl+0xa62/0xd00 fs/btrfs/ioctl.c:-1
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5178f9c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f51785dd028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5179216180 RCX: 00007f5178f9c629
RDX: 0000200000001480 RSI: 0000000050009417 RDI: 0000000000000003
RBP: 00007f5179032b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5179216218 R14: 00007f5179216180 R15: 00007ffc1c52f3d8
</TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.