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: 14d, last: 2d17h
Cause bisection: failed (error log, bisect log)
  
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ID Workflow Result Correct Bug Created Started Finished Revision
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+0x12d/0x470 fs/dlm/lowcomms.c:1455, CPU#1: syz-executor119/5598
Modules linked in:
CPU: 1 UID: 0 PID: 5598 Comm: syz-executor119 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:dlm_lowcomms_close+0x12d/0x470 fs/dlm/lowcomms.c:1455
Code: 09 ae 9d 00 eb a6 44 89 e1 80 e1 07 80 c1 03 38 c1 7c ac 4c 89 e7 e8 42 24 07 01 eb a2 e8 eb ad 9d 00 eb 05 e8 e4 ad 9d 00 90 <0f> 0b 90 44 89 f7 e8 48 72 4a 01 b8 fe ff ff ff 48 83 c4 20 5b 41
RSP: 0018:ffffc90004427c40 EFLAGS: 00010293
RAX: ffffffff81281a45 RBX: 0000000000000001 RCX: ffff888037e30000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000004 R09: ffffffff95c5cbc8
R10: 00000000088e0994 R11: 000000005f26ce64 R12: 0000000000000000
R13: ffffffff81281978 R14: 0000000000000000 R15: 0000000000000000
FS:  0000555593ba0400(0000) GS:ffff888125d46000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 00000000467ea000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 drop_comm+0x61/0x190 fs/dlm/config.c:556
 client_drop_item fs/configfs/dir.c:970 [inline]
 configfs_rmdir+0x85f/0x950 fs/configfs/dir.c:1567
 vfs_rmdir+0x3e9/0x6b0 fs/namei.c:5381
 filename_rmdir+0x292/0x520 fs/namei.c:5438
 __do_sys_rmdir fs/namei.c:5461 [inline]
 __se_sys_rmdir+0x2e/0x140 fs/namei.c:5458
 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: 0033:0x7fbfbf7d5589
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc721ba918 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 0073666769666e6f RCX: 00007fbfbf7d5589
RDX: 0000000000000000 RSI: 00007fbfbf7d5589 RDI: 0000200000000040
RBP: 6e6f635f796d2f2e R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 00007ffc721ba92c
R13: 431bde82d7b634db R14: 00007fbfbf868c40 R15: 0000000000000002
 </TASK>

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/11 19:21 upstream f5bbbfec59b4 71790083 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in dlm_lowcomms_close
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
2026/08/12 01:19 upstream f5bbbfec59b4 71790083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in dlm_lowcomms_close
2026/08/12 01:18 upstream f5bbbfec59b4 71790083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in dlm_lowcomms_close
2026/08/09 12:07 upstream 06cf61899d64 5d63f80b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root 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
2026/08/10 19:57 upstream db2ddb871435 558388e4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in dlm_lowcomms_close
2026/08/10 19:57 upstream db2ddb871435 558388e4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in dlm_lowcomms_close
2026/08/10 19:56 upstream db2ddb871435 558388e4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in dlm_lowcomms_close
2026/08/10 19:56 upstream db2ddb871435 558388e4 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 WARNING in dlm_lowcomms_close
* Struck through repros no longer work on HEAD.