[syzbot] [jfs?] kernel BUG in dbBackSplit (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 54e82e93ca93 Merge tag 'core_urgent_for_v6.19_rc4' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=153d8044580000
kernel config: https://syzkaller.appspot.com/x/.config?x=513255d80ab78f2b
dashboard link: https://syzkaller.appspot.com/bug?extid=5391ade36343d8cd8801
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-54e82e93.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f3befb5f53a4/vmlinux-54e82e93.xz
kernel image: https://storage.googleapis.com/syzbot-assets/92820ca1dbd8/bzImage-54e82e93.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5391ad...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
ERROR: (device loop0): dbAdjCtl: the maximum free buddy is not the old root
ERROR: (device loop0): remounting filesystem as read-only
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: 5338 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~bpo12+1 04/01/2014
RIP: 0010:dbBackSplit+0x57c/0x580 fs/jfs/jfs_dmap.c:2700
Code: e9 02 fc ff ff e8 54 a1 77 fe 48 c7 c7 e0 63 a5 8b 48 c7 c6 20 61 a5 8b ba 8c 0a 00 00 48 c7 c1 c0 6a a5 8b e8 65 42 de 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:ffffc9000ae3fbb8 EFLAGS: 00010246
RAX: 000000000000003c RBX: 000000000000000a RCX: 0078dd38eec66b00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff88801fc247d3 R09: 1ffff11003f848fa
R10: dffffc0000000000 R11: ffffed1003f848fb R12: 0000000000000020
R13: ffff888035fb4010 R14: ffff888035fb4096 R15: ffff888035fb4076
FS: 00007f8e5c1f56c0(0000) GS:ffff88808d414000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f271a34b000 CR3: 0000000043e21000 CR4: 0000000000352ef0
Call Trace:
<TASK>
dbFreeDmap fs/jfs/jfs_dmap.c:2108 [inline]
dbFree+0x54e/0x650 fs/jfs/jfs_dmap.c:398
dbDiscardAG+0x7bf/0x900 fs/jfs/jfs_dmap.c:1645
jfs_ioc_trim+0x429/0x690 fs/jfs/jfs_discard.c:106
jfs_ioctl+0x2b5/0x3d0 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+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8e5fd8f7c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8e5c1f5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f8e5ffe6090 RCX: 00007f8e5fd8f7c9
RDX: 0000200000000000 RSI: 00000000c0185879 RDI: 000000000000000a
RBP: 00007f8e5fe13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8e5ffe6128 R14: 00007f8e5ffe6090 R15: 00007ffe9f75d318
</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 54 a1 77 fe 48 c7 c7 e0 63 a5 8b 48 c7 c6 20 61 a5 8b ba 8c 0a 00 00 48 c7 c1 c0 6a a5 8b e8 65 42 de 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:ffffc9000ae3fbb8 EFLAGS: 00010246
RAX: 000000000000003c RBX: 000000000000000a RCX: 0078dd38eec66b00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff88801fc247d3 R09: 1ffff11003f848fa
R10: dffffc0000000000 R11: ffffed1003f848fb R12: 0000000000000020
R13: ffff888035fb4010 R14: ffff888035fb4096 R15: ffff888035fb4076
FS: 00007f8e5c1f56c0(0000) GS:ffff88808d414000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f271a362000 CR3: 0000000043e21000 CR4: 0000000000352ef0


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