BUG at fs/jfs/jfs_dmap.c:2983 assert(n < 4)
------------[ cut here ]------------
kernel BUG at fs/jfs/jfs_dmap.c:2983!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5324 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:dbFindLeaf+0x51d/0x520 fs/jfs/jfs_dmap.c:2983
Code: e9 4c ff ff ff e8 03 e6 6e fe 48 c7 c7 a0 b9 ea 8b 48 c7 c6 e0 b6 ea 8b ba a7 0b 00 00 48 c7 c1 c0 c4 ea 8b e8 34 10 d2 fd 90 <0f> 0b 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57
RSP: 0018:ffffc900096af118 EFLAGS: 00010246
RAX: 000000000000002b RBX: 0000000000000000 RCX: 799f6b28183bb300
RDX: ffffc90021003000 RSI: 0000000000003ed7 RDI: 0000000000003ed8
RBP: 0000000000000001 R08: ffffc900096aeea7 R09: 1ffff920012d5dd4
R10: dffffc0000000000 R11: fffff520012d5dd5 R12: 000000000000000a
R13: 0000000000000078 R14: 0000000000000075 R15: 0000000000000155
FS:  00007f8e2918a6c0(0000) GS:ffff88808ccea000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc422c58e3a CR3: 000000001204c000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 dbAllocDmapLev+0x60/0x3c0 fs/jfs/jfs_dmap.c:1969
 dbAlloc+0x994/0xba0 fs/jfs/jfs_dmap.c:844
 extBalloc fs/jfs/jfs_extent.c:336 [inline]
 extAlloc+0x57d/0x1020 fs/jfs/jfs_extent.c:127
 jfs_get_block+0x358/0xad0 fs/jfs/inode.c:254
 get_more_blocks fs/direct-io.c:648 [inline]
 do_direct_IO fs/direct-io.c:936 [inline]
 __blockdev_direct_IO+0x15d7/0x32f0 fs/direct-io.c:1243
 blockdev_direct_IO include/linux/fs.h:3077 [inline]
 jfs_direct_IO+0x119/0x220 fs/jfs/inode.c:339
 generic_file_direct_write+0x1db/0x3e0 mm/filemap.c:4248
 __generic_file_write_iter+0x11d/0x230 mm/filemap.c:4417
 generic_file_write_iter+0x14a/0x680 mm/filemap.c:4457
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x61d/0xb90 fs/read_write.c:686
 ksys_write+0x150/0x270 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8e2839aeb9
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:00007f8e2918a028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f8e28616090 RCX: 00007f8e2839aeb9
RDX: 00000000ffffffd7 RSI: 0000200000000000 RDI: 0000000000000007
RBP: 00007f8e28408c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8e28616128 R14: 00007f8e28616090 R15: 00007ffcde48d3d8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbFindLeaf+0x51d/0x520 fs/jfs/jfs_dmap.c:2983
Code: e9 4c ff ff ff e8 03 e6 6e fe 48 c7 c7 a0 b9 ea 8b 48 c7 c6 e0 b6 ea 8b ba a7 0b 00 00 48 c7 c1 c0 c4 ea 8b e8 34 10 d2 fd 90 <0f> 0b 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57
RSP: 0018:ffffc900096af118 EFLAGS: 00010246
RAX: 000000000000002b RBX: 0000000000000000 RCX: 799f6b28183bb300
RDX: ffffc90021003000 RSI: 0000000000003ed7 RDI: 0000000000003ed8
RBP: 0000000000000001 R08: ffffc900096aeea7 R09: 1ffff920012d5dd4
R10: dffffc0000000000 R11: fffff520012d5dd5 R12: 000000000000000a
R13: 0000000000000078 R14: 0000000000000075 R15: 0000000000000155
FS:  00007f8e2918a6c0(0000) GS:ffff88808ccea000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8e2860e0a0 CR3: 000000001204c000 CR4: 0000000000352ef0