BUG at fs/jfs/jfs_dmap.c:2983 assert(n < 4)
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kernel BUG at fs/jfs/jfs_dmap.c:2983!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 7536 Comm: syz.5.287 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:dbFindLeaf+0x51d/0x520 fs/jfs/jfs_dmap.c:2983
Code: e9 4c ff ff ff e8 e3 41 78 fe 48 c7 c7 a0 56 c5 8b 48 c7 c6 e0 53 c5 8b ba a7 0b 00 00 48 c7 c1 80 61 c5 8b e8 54 33 de 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:ffffc9000be8e190 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: 5cf2b0488dec6300
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffc9000be8dea7 R09: 1ffff920017d1bd4
R10: dffffc0000000000 R11: fffff520017d1bd5 R12: 0000000000000000
R13: 000000000000015c R14: 0000000000000159 R15: 0000000000000555
FS:  00007fb9c09db6c0(0000) GS:ffff888125d25000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00001ffffffffec0 CR3: 0000000011b9a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 dbFindCtl+0x267/0x520 fs/jfs/jfs_dmap.c:1717
 dbAllocAny fs/jfs/jfs_dmap.c:1527 [inline]
 dbAlloc+0x5fa/0xba0 fs/jfs/jfs_dmap.c:878
 extBalloc fs/jfs/jfs_extent.c:336 [inline]
 extAlloc+0x54a/0xfb0 fs/jfs/jfs_extent.c:127
 jfs_get_block+0x346/0xab0 fs/jfs/inode.c:254
 __block_write_begin_int+0x6b5/0x1900 fs/buffer.c:2145
 block_write_begin+0x8d/0x120 fs/buffer.c:2256
 jfs_write_begin+0x35/0x80 fs/jfs/inode.c:306
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4314
 generic_file_write_iter+0x117/0x550 mm/filemap.c:4457
 __kernel_write_iter+0x428/0x910 fs/read_write.c:619
 dump_emit_page fs/coredump.c:1298 [inline]
 dump_user_range+0x8a0/0xc90 fs/coredump.c:1372
 elf_core_dump+0x3369/0x3960 fs/binfmt_elf.c:2111
 coredump_write+0x1121/0x18b0 fs/coredump.c:1049
 do_coredump fs/coredump.c:1126 [inline]
 vfs_coredump+0x3321/0x3e60 fs/coredump.c:1200
 get_signal+0x1108/0x1340 kernel/signal.c:3019
 arch_do_signal_or_restart+0x9a/0x7a0 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:75 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
 irqentry_exit+0x177/0x660 kernel/entry/common.c:196
 exc_page_fault+0xab/0x100 arch/x86/mm/fault.c:1535
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 002b:0000200000000448 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007fb9bfde6180 RCX: 00007fb9bfb8f749
RDX: 0000000000000000 RSI: 0000200000000440 RDI: 0000000060100000
RBP: 00007fb9bfc13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007fb9bfde6218 R14: 00007fb9bfde6180 R15: 00007ffd2de75a78
 </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 e3 41 78 fe 48 c7 c7 a0 56 c5 8b 48 c7 c6 e0 53 c5 8b ba a7 0b 00 00 48 c7 c1 80 61 c5 8b e8 54 33 de 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:ffffc9000be8e190 EFLAGS: 00010246
RAX: 000000000000002b RBX: 00000000ffffffff RCX: 5cf2b0488dec6300
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: 0000000000000001 R08: ffffc9000be8dea7 R09: 1ffff920017d1bd4
R10: dffffc0000000000 R11: fffff520017d1bd5 R12: 0000000000000000
R13: 000000000000015c R14: 0000000000000159 R15: 0000000000000555
FS:  00007fb9c09db6c0(0000) GS:ffff888125d25000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f152f7b7198 CR3: 0000000011b9a000 CR4: 00000000003526f0