BUG at fs/jfs/jfs_dmap.c:2983 assert(n < 4)
------------[ cut here ]------------
kernel BUG at fs/jfs/jfs_dmap.c:2983!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 6501 Comm: syz.3.87 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:dbFindLeaf+0x517/0x520 fs/jfs/jfs_dmap.c:2983
Code: fe e9 51 ff ff ff e8 68 ea 87 fe 48 c7 c7 a0 cd e3 8a 48 c7 c6 e0 ca e3 8a ba a7 0b 00 00 48 c7 c1 80 d8 e3 8a e8 e9 84 5e 07 <0f> 0b 0f 1f 80 00 00 00 00 55 41 57 41 56 41 55 41 54 53 48 83 ec
RSP: 0018:ffffc9000486f298 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: c81ceda50ecc8d00
RDX: ffffc9000d9ec000 RSI: 000000000007161e RDI: 000000000007161f
RBP: 0000000000000001 R08: ffffc9000486efa7 R09: 1ffff9200090ddf4
R10: dffffc0000000000 R11: fffff5200090ddf5 R12: 0000000000000008
R13: 0000000000000060 R14: 000000000000005d R15: 0000000000000155
FS:  00007f07a24486c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f07a23e4f98 CR3: 00000000232ef000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 dbAllocDmapLev+0x61/0x3c0 fs/jfs/jfs_dmap.c:1969
 dbAlloc+0x98c/0xba0 fs/jfs/jfs_dmap.c:844
 extBalloc fs/jfs/jfs_extent.c:326 [inline]
 extAlloc+0x4d6/0xf30 fs/jfs/jfs_extent.c:122
 jfs_get_block+0x347/0xab0 fs/jfs/inode.c:254
 get_more_blocks fs/direct-io.c:647 [inline]
 do_direct_IO fs/direct-io.c:935 [inline]
 __blockdev_direct_IO+0x1679/0x3420 fs/direct-io.c:1248
 blockdev_direct_IO include/linux/fs.h:3047 [inline]
 jfs_direct_IO+0x11b/0x220 fs/jfs/inode.c:337
 generic_file_direct_write+0x1d4/0x3e0 mm/filemap.c:3956
 __generic_file_write_iter+0x11b/0x230 mm/filemap.c:4112
 generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4152
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x79a/0xc70 fs/read_write.c:860
 vfs_writev fs/read_write.c:933 [inline]
 do_pwritev+0x205/0x340 fs/read_write.c:1030
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f07a158f749
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:00007f07a2448038 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007f07a17e5fa0 RCX: 00007f07a158f749
RDX: 0000000000000001 RSI: 0000200000000240 RDI: 0000000000000004
RBP: 00007f07a1613f91 R08: 0000000000000000 R09: 0000000000000003
R10: 0000000000009c00 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f07a17e6038 R14: 00007f07a17e5fa0 R15: 00007ffed23a1ad8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbFindLeaf+0x517/0x520 fs/jfs/jfs_dmap.c:2983
Code: fe e9 51 ff ff ff e8 68 ea 87 fe 48 c7 c7 a0 cd e3 8a 48 c7 c6 e0 ca e3 8a ba a7 0b 00 00 48 c7 c1 80 d8 e3 8a e8 e9 84 5e 07 <0f> 0b 0f 1f 80 00 00 00 00 55 41 57 41 56 41 55 41 54 53 48 83 ec
RSP: 0018:ffffc9000486f298 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: c81ceda50ecc8d00
RDX: ffffc9000d9ec000 RSI: 000000000007161e RDI: 000000000007161f
RBP: 0000000000000001 R08: ffffc9000486efa7 R09: 1ffff9200090ddf4
R10: dffffc0000000000 R11: fffff5200090ddf5 R12: 0000000000000008
R13: 0000000000000060 R14: 000000000000005d R15: 0000000000000155
FS:  00007f07a24486c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc86233d34 CR3: 00000000232ef000 CR4: 00000000003506f0