syzbot


WARNING in lookup_inline_extent_backref (2)

Status: upstream: reported C repro on 2025/10/27 09:05
Subsystems: btrfs
[Documentation on labels]
Reported-by: syzbot+b0e66d3779134f468156@syzkaller.appspotmail.com
First crash: 125d, last: 3d03h
Cause bisection: failed (error log, bisect log)
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [btrfs?] WARNING in lookup_inline_extent_backref (2) 1 (3) 2026/02/22 05:56
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING in lookup_inline_extent_backref origin:lts-only -1 C done 5 942d 1061d 0/3 auto-obsoleted due to no activity on 2024/10/04 17:22
upstream WARNING in lookup_inline_extent_backref btrfs -1 C error inconclusive 304 254d 1178d 0/29 auto-obsoleted due to no activity on 2025/08/25 22:17
linux-6.1 WARNING in lookup_inline_extent_backref origin:upstream -1 C done 2 816d 983d 3/3 fixed on 2024/01/01 13:36

Sample crash report:
---------[  113.668460][ T6044] ------------[ cut here ]------------
ret
WARNING: fs/btrfs/extent-tree.c:837 at lookup_inline_extent_backref+0x143e/0x1980 fs/btrfs/extent-tree.c:837, CPU#1: syz.0.18/6044
Modules linked in:
CPU: 1 UID: 0 PID: 6044 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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 c8 4d 4a 07 cc e8 82 1d e9 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:ffffc90003b66dc0 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffff888032d2dac0
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90003b66fe8 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff94000224951 R12: 0000000000510000
R13: ffff888044855c60 R14: 0000000000000009 R15: ffff88805b6b0000
FS:  00007f14435fd6c0(0000) GS:ffff888126443000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000002000 CR3: 000000003a9da000 CR4: 00000000003526f0
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+0x191/0x3b0 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+0x534/0x750 fs/btrfs/ioctl.c:1163
 btrfs_ioctl_snap_create_v2+0x1fb/0x3b0 fs/btrfs/ioctl.c:1242
 btrfs_ioctl+0xa65/0xd00 fs/btrfs/ioctl.c:-1
 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+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1443fbc629
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:00007f14435fd028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f1444236090 RCX: 00007f1443fbc629
RDX: 0000200000001480 RSI: 0000000050009417 RDI: 0000000000000003
RBP: 00007f1444052b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1444236128 R14: 00007f1444236090 R15: 00007ffc2861aba8
 </TASK>

Crashes (18):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/22 08:31 upstream fa5c82f4d2bb 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-upstream-fs WARNING in lookup_inline_extent_backref
2026/02/22 05:55 upstream d79526b89571 6e7b5511 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2026/02/11 20:48 upstream 192c0159402e 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in lookup_inline_extent_backref
2026/02/11 20:36 upstream 192c0159402e 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in lookup_inline_extent_backref
2026/02/11 20:36 upstream 192c0159402e 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in lookup_inline_extent_backref
2026/02/22 04:49 upstream d79526b89571 6e7b5511 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2026/02/12 17:47 upstream 37a93dd5c49b 504cb1bf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2026/02/12 17:45 upstream 37a93dd5c49b 504cb1bf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2026/02/12 17:44 upstream 37a93dd5c49b 504cb1bf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2026/02/12 17:43 upstream 37a93dd5c49b 504cb1bf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2026/02/12 04:20 upstream 1e83ccd5921a 76a109e2 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2025/11/26 03:17 upstream 8a2bcda5e139 bf6fe8fe .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2025/11/02 02:52 upstream 691d401c7e0e 2c50b6a9 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2025/10/29 01:28 upstream 8eefed8f65cc fd2207e7 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2025/10/29 01:11 upstream 8eefed8f65cc fd2207e7 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2025/10/26 20:51 upstream dbfc6422a34d c0460fcd .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2025/10/25 13:55 upstream 566771afc7a8 c0460fcd .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
2025/10/23 09:03 upstream 43e9ad0c55a3 c0460fcd .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in lookup_inline_extent_backref
* Struck through repros no longer work on HEAD.