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BUG: unable to handle page fault for address: fffffffffffffffc
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 7012067 P4D 7012067 PUD 7014067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 377 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:ext4_ext_drop_refs fs/ext4/extents.c:119 [inline]
RIP: 0010:ext4_free_ext_path fs/ext4/extents.c:128 [inline]
RIP: 0010:ext4_ext_map_blocks+0x2e59/0x6200 fs/ext4/extents.c:4497
Code: 40 01 00 00 4d 85 f6 0f 84 bc 00 00 00 48 89 5c 24 20 49 8d 7e 08 48 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 38 16 00 00 <41> 0f b7 46 08 c1 e0 04 48 8d 04 40 48 89 44 24 08 49 8d 46 28 48
RSP: 0018:ffffc90000a56600 EFLAGS: 00010246

RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff888115701440
RDX: 0000000000000000 RSI: 0000000000000000 RDI: fffffffffffffffc
RBP: ffffc90000a568b0 R08: ffff88810b5f6ae3 R09: 1ffff110216bed5c
R10: dffffc0000000000 R11: ffffed10216bed5d R12: dffffc0000000000
R13: 1ffff9200014acec R14: fffffffffffffff4 R15: 0000000000000010
FS:  0000555592bf4500(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 000000012d4cd000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_map_blocks+0x9d8/0x1b70 fs/ext4/inode.c:679
 _ext4_get_block+0x1ea/0x540 fs/ext4/inode.c:822
 ext4_get_block_unwritten+0x2e/0x100 fs/ext4/inode.c:855
 ext4_block_write_begin+0x594/0x1280 fs/ext4/inode.c:1124
 ext4_write_begin+0x600/0xf90 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x3e7/0x8c0 fs/ext4/inode.c:3001
 generic_perform_write+0x32d/0x740 mm/filemap.c:3914
 ext4_buffered_write_iter+0x367/0x630 fs/ext4/file.c:285
 ext4_file_write_iter+0x191/0x1500 fs/ext4/file.c:-1
 __kernel_write_iter+0x296/0x660 fs/read_write.c:517
 dump_emit_page fs/coredump.c:886 [inline]
 dump_user_range+0x40b/0x660 fs/coredump.c:913
 elf_core_dump+0x2b52/0x3060 fs/binfmt_elf.c:2354
 do_coredump+0x15d3/0x2240 fs/coredump.c:760
 get_signal+0x11db/0x1520 kernel/signal.c:2877
 arch_do_signal_or_restart+0xd1/0x1140 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 irqentry_exit_to_user_mode+0x9/0x10 kernel/entry/common.c:316
 irqentry_exit+0x12/0x40 kernel/entry/common.c:419
 exc_page_fault+0x5e/0xb0 arch/x86/mm/fault.c:1520
 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7fd65c59ce61
Code: 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 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007fd65c815fa0 RCX: 00007fd65c59ce59
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007fd65c632d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007fd65c815fac R14: 00007fd65c815fa0 R15: 00007fd65c815fa0
 </TASK>
Modules linked in:
CR2: fffffffffffffffc
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_ext_drop_refs fs/ext4/extents.c:119 [inline]
RIP: 0010:ext4_free_ext_path fs/ext4/extents.c:128 [inline]
RIP: 0010:ext4_ext_map_blocks+0x2e59/0x6200 fs/ext4/extents.c:4497
Code: 40 01 00 00 4d 85 f6 0f 84 bc 00 00 00 48 89 5c 24 20 49 8d 7e 08 48 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 38 16 00 00 <41> 0f b7 46 08 c1 e0 04 48 8d 04 40 48 89 44 24 08 49 8d 46 28 48
RSP: 0018:ffffc90000a56600 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff888115701440
RDX: 0000000000000000 RSI: 0000000000000000 RDI: fffffffffffffffc
RBP: ffffc90000a568b0 R08: ffff88810b5f6ae3 R09: 1ffff110216bed5c
R10: dffffc0000000000 R11: ffffed10216bed5d R12: dffffc0000000000
R13: 1ffff9200014acec R14: fffffffffffffff4 R15: 0000000000000010
FS:  0000555592bf4500(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 000000012d4cd000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	40 01 00             	rex add %eax,(%rax)
   3:	00 4d 85             	add    %cl,-0x7b(%rbp)
   6:	f6 0f 84             	testb  $0x84,(%rdi)
   9:	bc 00 00 00 48       	mov    $0x48000000,%esp
   e:	89 5c 24 20          	mov    %ebx,0x20(%rsp)
  12:	49 8d 7e 08          	lea    0x8(%r14),%rdi
  16:	48 89 f8             	mov    %rdi,%rax
  19:	48 c1 e8 03          	shr    $0x3,%rax
  1d:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax
  22:	84 c0                	test   %al,%al
  24:	0f 85 38 16 00 00    	jne    0x1662
* 2a:	41 0f b7 46 08       	movzwl 0x8(%r14),%eax <-- trapping instruction
  2f:	c1 e0 04             	shl    $0x4,%eax
  32:	48 8d 04 40          	lea    (%rax,%rax,2),%rax
  36:	48 89 44 24 08       	mov    %rax,0x8(%rsp)
  3b:	49 8d 46 28          	lea    0x28(%r14),%rax
  3f:	48                   	rex.W