syzbot


kernel BUG in dbBackSplit (2)

Status: upstream: reported on 2026/01/09 20:35
Subsystems: jfs
[Documentation on labels]
Reported-by: syzbot+5391ade36343d8cd8801@syzkaller.appspotmail.com
First crash: 99d, last: 18d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
945dd1d2-37bc-4eb7-9fcd-bdd22d30f1aa repro kernel BUG in dbBackSplit (2) 2026/03/10 13:48 2026/03/11 12:40 2026/03/11 13:04 86914af9098a80da53c3c5d46be980c572ee29f8
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [jfs?] kernel BUG in dbBackSplit (2) 0 (1) 2026/01/09 20:35
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in dbBackSplit jfs -1 2 580d 576d 0/29 auto-obsoleted due to no activity on 2024/12/20 17:49

Sample crash report:
netlink: 4 bytes leftover after parsing attributes in process `syz.0.0'.
loop0: detected capacity change from 0 to 32768
read_mapping_page failed!
read_mapping_page failed!
BUG at fs/jfs/jfs_dmap.c:2700 assert(leaf[leafno] == NOFREE)
------------[ cut here ]------------
kernel BUG at fs/jfs/jfs_dmap.c:2700!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5333 Comm: syz.0.0 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:dbBackSplit+0x57c/0x580 fs/jfs/jfs_dmap.c:2700
Code: e9 02 fc ff ff e8 a4 b0 68 fe 48 c7 c7 20 3e 0b 8c 48 c7 c6 60 3b 0b 8c ba 8c 0a 00 00 48 c7 c1 40 45 0b 8c e8 15 ae ca fd 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41
RSP: 0018:ffffc9000e10fbc0 EFLAGS: 00010246
RAX: 000000000000003c RBX: 000000000000000a RCX: 0d005ca08040ad00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1cbd630 R12: 0000000000000040
R13: ffff88801fc55010 R14: ffff88801fc550b6 R15: ffff88801fc55076
FS:  00007fecbe27a6c0(0000) GS:ffff88808ca4e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f050d028000 CR3: 0000000044754000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 dbFreeDmap fs/jfs/jfs_dmap.c:2108 [inline]
 dbFree+0x54e/0x650 fs/jfs/jfs_dmap.c:398
 dbDiscardAG+0x7b9/0x8f0 fs/jfs/jfs_dmap.c:1645
 jfs_ioc_trim+0x429/0x690 fs/jfs/jfs_discard.c:106
 jfs_ioctl+0x28e/0x3b0 fs/jfs/ioctl.c:131
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/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: 0033:0x7fecbd39c799
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:00007fecbe279fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fecbd616090 RCX: 00007fecbd39c799
RDX: 00002000000000c0 RSI: 00000000c0185879 RDI: 000000000000000b
RBP: 00007fecbd432c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fecbd616128 R14: 00007fecbd616090 R15: 00007fff8a546378
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbBackSplit+0x57c/0x580 fs/jfs/jfs_dmap.c:2700
Code: e9 02 fc ff ff e8 a4 b0 68 fe 48 c7 c7 20 3e 0b 8c 48 c7 c6 60 3b 0b 8c ba 8c 0a 00 00 48 c7 c1 40 45 0b 8c e8 15 ae ca fd 90 <0f> 0b 66 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41
RSP: 0018:ffffc9000e10fbc0 EFLAGS: 00010246
RAX: 000000000000003c RBX: 000000000000000a RCX: 0d005ca08040ad00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1cbd630 R12: 0000000000000040
R13: ffff88801fc55010 R14: ffff88801fc550b6 R15: ffff88801fc55076
FS:  00007fecbe27a6c0(0000) GS:ffff88808ca4e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f050c87f201 CR3: 0000000044754000 CR4: 0000000000352ef0

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/28 00:34 upstream 7df48e363130 f9ef2ec1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root kernel BUG in dbBackSplit
2026/01/06 08:57 upstream 54e82e93ca93 d1b870e1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root kernel BUG in dbBackSplit
2026/01/05 20:24 upstream 54e82e93ca93 d1b870e1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root kernel BUG in dbBackSplit
* Struck through repros no longer work on HEAD.