------------[ cut here ]------------
WARNING: CPU: 1 PID: 9115 at fs/buffer.c:1081 mark_buffer_dirty+0x383/0x7a0 fs/buffer.c:1081
Modules linked in:
CPU: 1 PID: 9115 Comm: syz.6.998 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:mark_buffer_dirty+0x383/0x7a0 fs/buffer.c:1081
Code: 13 d1 e2 ff 49 8b 3f be 04 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d e9 bc bc fc ff e8 a7 9f 92 ff e9 43 ff ff ff e8 9d 9f 92 ff <0f> 0b e9 ba fc ff ff e8 91 9f 92 ff 0f 0b e9 00 fd ff ff e8 85 9f
RSP: 0018:ffffc9000496f858 EFLAGS: 00010283
RAX: ffffffff81ee4033 RBX: ffff888040800bc8 RCX: 0000000000080000
RDX: ffffc9000e7c3000 RSI: 000000000001f03d RDI: 000000000001f03e
RBP: ffff888140c91201 R08: dffffc0000000000 R09: ffffed100810017a
R10: ffffed100810017a R11: 1ffff11008100179 R12: dffffc0000000000
R13: ffff888040891008 R14: ffffea0001351c98 R15: ffff888040800bc8
FS:  00007f4acd09f6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555580a2e808 CR3: 0000000064fbe000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 mark_buffer_dirty_inode+0x82/0x2e0 fs/buffer.c:575
 fat12_ent_put+0x1af/0x2e0 fs/fat/fatent.c:173
 fat_free_clusters+0x441/0xb70 fs/fat/fatent.c:597
 fat_alloc_new_dir+0x760/0xbd0 fs/fat/dir.c:1192
 vfat_mkdir+0x122/0x2a0 fs/fat/namei_vfat.c:859
 vfs_mkdir+0x387/0x570 fs/namei.c:4114
 do_mkdirat+0x1d0/0x430 fs/namei.c:4139
 __do_sys_mkdir fs/namei.c:4159 [inline]
 __se_sys_mkdir fs/namei.c:4157 [inline]
 __x64_sys_mkdir+0x6a/0x80 fs/namei.c:4157
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f4acc18f749
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:00007f4acd09f038 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007f4acc3e6090 RCX: 00007f4acc18f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000100
RBP: 00007f4acc213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4acc3e6128 R14: 00007f4acc3e6090 R15: 00007ffd5eb98478
 </TASK>