WARNING in btrfs_init_new_device

Status: upstream: reported C repro on 2026/08/10 00:34
Subsystems: btrfs
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+3bf3e110b2d406b8166c@syzkaller.appspotmail.com
First crash: 10d, last: 1d07h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
07037795 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in btrfs_init_new_device 2026/08/09 18:58 2026/08/09 18:58 2026/08/09 19:30 5d63f80b
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [btrfs?] WARNING in btrfs_init_new_device 0 (2) 2026/08/13 05:45
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 WARNING in btrfs_init_new_device -1 1 10d 10d 0/3 upstream: reported on 2026/08/04 19:58

Sample crash report:
------------[ cut here ]------------
btrfs_abort_should_print_stack(__error)
WARNING: fs/btrfs/volumes.c:3013 at btrfs_init_new_device+0x1913/0x19e0 fs/btrfs/volumes.c:3013, CPU#1: syz.0.17/5924
Modules linked in:
CPU: 1 UID: 0 PID: 5924 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:btrfs_init_new_device+0x1913/0x19e0 fs/btrfs/volumes.c:3013
Code: 00 00 41 83 fe f4 0f 85 d8 00 00 00 e8 d6 c3 b4 fd e9 d7 00 00 00 e8 cc c3 b4 fd eb 10 e8 c5 c3 b4 fd eb 09 e8 be c3 b4 fd 90 <0f> 0b 90 44 89 f1 f7 d9 e9 7b fc ff ff 89 d9 80 e1 07 38 c1 0f 8c
RSP: 0018:ffffc90003f07da8 EFLAGS: 00010293
RAX: ffffffff84110472 RBX: ffff8880357dc001 RCX: ffff8880381a5d00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffff8880381a5d00 R09: 0000000000000003
R10: 0000000000000100 R11: 00000000fffffffb R12: ffff8880357dce40
R13: 0000000000000001 R14: 00000000ffffffef R15: ffff8880357dc000
FS:  00007fc65910e6c0(0000) GS:ffff888125d46000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc659afb7c0 CR3: 00000000472b8000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 btrfs_ioctl_add_dev+0x1ad/0x640 fs/btrfs/ioctl.c:2558
 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+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc659aae0d9
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:00007fc65910e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fc659d35fa0 RCX: 00007fc659aae0d9
RDX: 0000200000001000 RSI: 000000005000940a RDI: 0000000000000004
RBP: 00007fc659b45024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc659d36038 R14: 00007fc659d35fa0 R15: 00007fff92859458
 </TASK>

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/13 05:44 upstream 3d6d817622b0 359b2492 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-upstream-fs WARNING in btrfs_init_new_device
2026/08/13 13:41 upstream 3d6d817622b0 359b2492 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in btrfs_init_new_device
2026/08/13 04:39 upstream 3d6d817622b0 359b2492 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in btrfs_init_new_device
2026/08/04 20:20 upstream 848acc8ffe1b d4abbeac .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in btrfs_init_new_device
2026/08/13 20:16 upstream 3d6d817622b0 4d118901 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in btrfs_init_new_device
2026/08/09 21:42 upstream b643e495ae92 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in btrfs_init_new_device
2026/08/08 10:33 upstream 3f008280327b 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in btrfs_init_new_device
2026/08/08 08:57 upstream 3f008280327b 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in btrfs_init_new_device
2026/08/08 08:02 upstream 3f008280327b 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in btrfs_init_new_device
2026/08/07 05:37 upstream fcaeecb8b0cd c38879ea .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in btrfs_init_new_device
2026/08/05 04:09 upstream 562bfb501c54 52aa2820 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in btrfs_init_new_device
* Struck through repros no longer work on HEAD.