WARNING in dlm_lowcomms_close

Status: upstream: reported C repro on 2026/07/31 17:14
Subsystems: gfs2
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+04dfbd15d442517e713a@syzkaller.appspotmail.com
First crash: 2d04h, last: 2d02h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
2e19a72d assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in dlm_lowcomms_close 2026/08/01 01:06 2026/08/01 01:06 2026/08/01 02:02 7664cf44

			
		
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [gfs2?] WARNING in dlm_lowcomms_close 0 (1) 2026/07/31 17:14

Sample crash report:
dlm: closing connection to node 1
------------[ cut here ]------------
!con
WARNING: fs/dlm/lowcomms.c:1455 at dlm_lowcomms_close+0x3d/0x21b fs/dlm/lowcomms.c:1455, CPU#1: syz.0.18/5929
Modules linked in:
CPU: 1 UID: 0 PID: 5929 Comm: syz.0.18 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:dlm_lowcomms_close+0x3d/0x21b fs/dlm/lowcomms.c:1455
Code: 89 ee 48 c7 c7 00 eb eb 8b e8 8f 61 fc ff e8 da f8 ff ff 31 f6 89 ef 41 89 c4 e8 9e 0f a1 01 48 85 c0 75 1b e8 d4 77 e4 00 90 <0f> 0b 90 44 89 e7 bb fe ff ff ff e8 43 f8 ff ff e9 b5 01 00 00 48
RSP: 0018:ffffc9000383fbd8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff82c6f9c4
RDX: ffff888033a52540 RSI: ffffffff8125e92c RDI: ffff888033a52540
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: 0000000000000001 R14: ffffed1005244e10 R15: 0000000000000001
FS:  0000555565d9e500(0000) GS:ffff8880d5eda000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b33163fff CR3: 000000002cf16000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 dlm_midcomms_close+0x312/0x590 fs/dlm/midcomms.c:1443
 drop_comm+0x62/0x1a0 fs/dlm/config.c:556
 client_drop_item+0xa6/0x100 fs/configfs/dir.c:970
 configfs_rmdir+0x5d3/0x950 fs/configfs/dir.c:1567
 vfs_rmdir fs/namei.c:5381 [inline]
 vfs_rmdir+0x328/0x8a0 fs/namei.c:5354
 filename_rmdir+0x31a/0x5c0 fs/namei.c:5438
 __do_sys_rmdir fs/namei.c:5461 [inline]
 __se_sys_rmdir fs/namei.c:5458 [inline]
 __x64_sys_rmdir+0x46/0x70 fs/namei.c:5458
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa842f9e019
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:00007ffc8c738bb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007fa843225fa0 RCX: 00007fa842f9e019
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000040
RBP: 00007fa84303500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa843225fac R14: 00007fa843225fa0 R15: 00007fa843225fa0
 </TASK>

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/31 06:40 upstream 3708dd948844 aaffb173 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in dlm_lowcomms_close
2026/07/31 05:59 upstream 3708dd948844 aaffb173 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in dlm_lowcomms_close
2026/07/31 05:28 upstream 3708dd948844 aaffb173 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in dlm_lowcomms_close
2026/07/31 04:48 upstream 3708dd948844 aaffb173 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in dlm_lowcomms_close
2026/07/31 04:03 upstream 3708dd948844 aaffb173 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in dlm_lowcomms_close
2026/07/31 04:02 upstream 3708dd948844 aaffb173 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream WARNING in dlm_lowcomms_close
* Struck through repros no longer work on HEAD.