EXT4-fs (loop2): This should not happen!! Data will be lost
------------[ cut here ]------------
WARNING: mm/page-writeback.c:2710 at __folio_mark_dirty+0x1fb/0xe00 mm/page-writeback.c:2710, CPU#1: syz.2.132/6883
Modules linked in:
CPU: 1 UID: 0 PID: 6883 Comm: syz.2.132 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__folio_mark_dirty+0x1fb/0xe00 mm/page-writeback.c:2710
Code: 3c 38 00 74 08 48 89 df e8 22 cf 26 00 4c 8b 33 4c 89 f6 48 83 e6 08 31 ff e8 61 9b c4 ff 49 83 e6 08 75 1c e8 f6 95 c4 ff 90 <0f> 0b 90 eb 16 e8 eb 95 c4 ff e9 6e 07 00 00 e8 e1 95 c4 ff eb 05
RSP: 0018:ffffc9000c847470 EFLAGS: 00010283
RAX: ffffffff81fb168a RBX: ffffea0000fd7a80 RCX: 0000000000080000
RDX: ffffc9000dd83000 RSI: 000000000000f2de RDI: 000000000000f2df
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff940001faf51 R12: ffff88804ad9b530
R13: ffff88804ad9b528 R14: 0000000000000000 R15: dffffc0000000000
FS:  00007f25901066c0(0000) GS:ffff888126def000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000000 CR3: 000000003a6c0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 block_dirty_folio+0x17a/0x1d0 fs/buffer.c:754
 fault_dirty_shared_page+0x103/0x550 mm/memory.c:3558
 wp_page_shared mm/memory.c:3945 [inline]
 do_wp_page+0x265e/0x4970 mm/memory.c:4148
 handle_pte_fault mm/memory.c:6289 [inline]
 __handle_mm_fault mm/memory.c:6411 [inline]
 handle_mm_fault+0x9f6/0x1330 mm/memory.c:6580
 do_user_addr_fault+0x764/0x1380 arch/x86/mm/fault.c:1387
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x71/0xd0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0010:__put_user_4+0xd/0x20 arch/x86/lib/putuser.S:94
Code: 66 89 01 31 c9 0f 01 ca c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 48 89 cb 48 c1 fb 3f 48 09 d9 0f 01 cb <89> 01 31 c9 0f 01 ca e9 c7 4c 04 00 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000c847a58 EFLAGS: 00050206
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000200000000000
RDX: 0000000000000000 RSI: ffffffff8cfdf4eb RDI: ffffffff8b3f57e0
RBP: ffffc9000c847c10 R08: ffffffff820a7bf0 R09: ffff888024de83b0
R10: dffffc0000000000 R11: ffffed10095b367f R12: 0000000000000000
R13: 1ffff92001908f50 R14: 0000200000000000 R15: 0000000000000000
 ioctl_fibmap fs/ioctl.c:90 [inline]
 file_ioctl+0x6dd/0x780 fs/ioctl.c:326
 do_vfs_ioctl+0xb36/0x1440 fs/ioctl.c:576
 __do_sys_ioctl fs/ioctl.c:595 [inline]
 __se_sys_ioctl+0x82/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2591e9f749
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:00007f2590106038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f25920f5fa0 RCX: 00007f2591e9f749
RDX: 0000200000000000 RSI: 0000000000000001 RDI: 0000000000000006
RBP: 00007f2591f23f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f25920f6038 R14: 00007f25920f5fa0 R15: 00007ffc5a45f738
 </TASK>
----------------
Code disassembly (best guess):
   0:	66 89 01             	mov    %ax,(%rcx)
   3:	31 c9                	xor    %ecx,%ecx
   5:	0f 01 ca             	clac
   8:	c3                   	ret
   9:	cc                   	int3
   a:	cc                   	int3
   b:	cc                   	int3
   c:	cc                   	int3
   d:	90                   	nop
   e:	90                   	nop
   f:	90                   	nop
  10:	90                   	nop
  11:	90                   	nop
  12:	90                   	nop
  13:	90                   	nop
  14:	90                   	nop
  15:	90                   	nop
  16:	90                   	nop
  17:	90                   	nop
  18:	90                   	nop
  19:	90                   	nop
  1a:	90                   	nop
  1b:	90                   	nop
  1c:	90                   	nop
  1d:	48 89 cb             	mov    %rcx,%rbx
  20:	48 c1 fb 3f          	sar    $0x3f,%rbx
  24:	48 09 d9             	or     %rbx,%rcx
  27:	0f 01 cb             	stac
* 2a:	89 01                	mov    %eax,(%rcx) <-- trapping instruction
  2c:	31 c9                	xor    %ecx,%ecx
  2e:	0f 01 ca             	clac
  31:	e9 c7 4c 04 00       	jmp    0x44cfd
  36:	90                   	nop
  37:	90                   	nop
  38:	90                   	nop
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop