loop2: detected capacity change from 0 to 32768
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:1385:9
shift exponent -4598 is negative
CPU: 0 UID: 0 PID: 10584 Comm: syz.2.516 Not tainted 6.15.0-rc3-syzkaller-00342-g5bc1018675ec #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x40 lib/ubsan.c:231
 __ubsan_handle_shift_out_of_bounds+0x386/0x410 lib/ubsan.c:492
 dbAllocAG+0xe0f/0xf10 fs/jfs/jfs_dmap.c:1385
 dbAlloc+0x5a8/0xba0 fs/jfs/jfs_dmap.c:873
 diNewExt+0x9af/0x3150 fs/jfs/jfs_imap.c:2261
 diAllocExt fs/jfs/jfs_imap.c:1952 [inline]
 diAllocAG+0xe86/0x1df0 fs/jfs/jfs_imap.c:1669
 diAlloc+0x1d5/0x1680 fs/jfs/jfs_imap.c:1590
 ialloc+0x8c/0x8f0 fs/jfs/jfs_inode.c:56
 jfs_mkdir+0x193/0xa70 fs/jfs/namei.c:225
 vfs_mkdir+0x303/0x510 fs/namei.c:4359
 do_mkdirat+0x247/0x590 fs/namei.c:4392
 __do_sys_mkdir fs/namei.c:4414 [inline]
 __se_sys_mkdir fs/namei.c:4412 [inline]
 __x64_sys_mkdir+0x6c/0x80 fs/namei.c:4412
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7efd93b8e969
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:00007efd94937038 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007efd93db5fa0 RCX: 00007efd93b8e969
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000200000000080
RBP: 00007efd93c10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007efd93db5fa0 R15: 00007ffd6a3b2658
 </TASK>
---[ end trace ]---