kernel BUG in lbmIOWait

Status: upstream: reported on 2026/07/10 18:24
Subsystems: jfs
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+2e5cf2352e9f69ebf172@syzkaller.appspotmail.com
First crash: 55d, last: 6h13m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
25ac41b7 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ kernel BUG in lbmIOWait 2026/07/08 01:27 2026/07/08 01:27 2026/07/08 02:19 93f57954
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [jfs?] kernel BUG in lbmIOWait 0 (1) 2026/07/10 18:24

Sample crash report:
BUG at fs/jfs/jfs_logmgr.c:1919 assert(bp->l_wqnext == NULL)
------------[ cut here ]------------
kernel BUG at fs/jfs/jfs_logmgr.c:1919!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 7361 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:lbmfree fs/jfs/jfs_logmgr.c:1919 [inline]
RIP: 0010:lbmIOWait+0x5ab/0x5b0 fs/jfs/jfs_logmgr.c:2154
Code: e9 c7 fc ff ff e8 65 6c 5f fe 48 c7 c7 80 52 ad 8b 48 c7 c6 80 4d ad 8b ba 7f 07 00 00 48 c7 c1 00 5b ad 8b e8 66 5e c0 fd 90 <0f> 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55
RSP: 0018:ffffc900048679e0 EFLAGS: 00010246
RAX: 000000000000003c RBX: ffff888034e0e208 RCX: 7c27c126ddcb9e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90004867af0 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff5200090ceed R12: 000000000000002e
R13: ffff888034e0e210 R14: dffffc0000000000 R15: 1ffff9200090cf44
FS:  0000555561dac500(0000) GS:ffff888125bd6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f51d1a56000 CR3: 0000000033fb2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lmLogShutdown+0x1ff/0x850 fs/jfs/jfs_logmgr.c:1657
 lmLogClose+0x28c/0x530 fs/jfs/jfs_logmgr.c:1457
 jfs_umount+0x2da/0x3b0 fs/jfs/jfs_umount.c:124
 jfs_put_super+0x8c/0x190 fs/jfs/super.c:194
 generic_shutdown_super+0x13d/0x2d0 fs/super.c:769
 kill_block_super+0x44/0xa0 fs/super.c:1918
 deactivate_locked_super+0xbc/0x110 fs/super.c:603
 cleanup_mnt+0x3d3/0x460 fs/namespace.c:1317
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
 exit_to_user_mode_loop+0x204/0x770 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
 do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4efc84f397
Code: a2 c7 05 5c 43 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fffa042be08 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f4efc8e4474 RCX: 00007f4efc84f397
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fffa042bec0
RBP: 00007fffa042bec0 R08: 00007fffa042cec0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffa042cf50
R13: 00007f4efc8e4474 R14: 000000000005c7be R15: 00007fffa042cf90
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:lbmfree fs/jfs/jfs_logmgr.c:1919 [inline]
RIP: 0010:lbmIOWait+0x5ab/0x5b0 fs/jfs/jfs_logmgr.c:2154
Code: e9 c7 fc ff ff e8 65 6c 5f fe 48 c7 c7 80 52 ad 8b 48 c7 c6 80 4d ad 8b ba 7f 07 00 00 48 c7 c1 00 5b ad 8b e8 66 5e c0 fd 90 <0f> 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55
RSP: 0018:ffffc900048679e0 EFLAGS: 00010246
RAX: 000000000000003c RBX: ffff888034e0e208 RCX: 7c27c126ddcb9e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90004867af0 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff5200090ceed R12: 000000000000002e
R13: ffff888034e0e210 R14: dffffc0000000000 R15: 1ffff9200090cf44
FS:  0000555561dac500(0000) GS:ffff888125bd6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd093984000 CR3: 0000000033fb2000 CR4: 00000000003526f0

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/30 13:38 upstream 08dbfad3f504 2f52988a .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in lbmIOWait
2026/07/30 16:51 upstream 11028ab62899 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in lbmIOWait
2026/07/06 18:13 upstream 8cdeaa50eae8 88b240e4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in lbmIOWait
* Struck through repros no longer work on HEAD.