EXT4-fs error (device loop0): ext4_map_blocks:745: inode #15: comm kworker/u4:6: lblock 0 mapped to illegal pblock 0 (length 1)
EXT4-fs (loop0): Delayed block allocation failed for inode 15 at logical offset 0 with max blocks 1 with error 117
EXT4-fs (loop0): This should not happen!! Data will be lost
EXT4-fs error (device loop0): ext4_validate_block_bitmap:438: comm kworker/u4:6: bg 0: block 112: padding at end of block bitmap is not set
BUG: unable to handle page fault for address: ffffffffffffffec
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD c891067 P4D c891067 PUD c893067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 4331 Comm: kworker/u4:6 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: writeback wb_workfn (flush-7:0)
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+0x362d/0x6870 fs/ext4/extents.c:4497
Code: 18 4c 8b b4 24 60 01 00 00 4d 85 f6 0f 84 b2 00 00 00 49 8d 7e 08 48 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 aa 12 00 00 <41> 0f b7 46 08 c1 e0 04 48 8d 04 40 48 89 44 24 50 49 8d 46 28 48
RSP: 0018:ffffc900041b6be0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888054df7108 RCX: ffff88802a885940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffffffffec
RBP: ffffc900041b6eb0 R08: ffffffff90af72df R09: 1ffffffff215ee5b
R10: dffffc0000000000 R11: fffffbfff215ee5c R12: dffffc0000000000
R13: 1ffff92000836dac R14: ffffffffffffffe4 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffec CR3: 000000007e770000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_map_blocks+0x9de/0x1b70 fs/ext4/inode.c:679
 mpage_map_one_extent fs/ext4/inode.c:2434 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2487 [inline]
 ext4_writepages+0x13c7/0x2f40 fs/ext4/inode.c:2855
 do_writepages+0x3ba/0x640 mm/page-writeback.c:2491
 __writeback_single_inode+0x156/0x1160 fs/fs-writeback.c:1622
 writeback_sb_inodes+0xb30/0x1850 fs/fs-writeback.c:1913
 wb_writeback+0x482/0xd50 fs/fs-writeback.c:2087
 wb_do_writeback fs/fs-writeback.c:2230 [inline]
 wb_workfn+0x423/0xee0 fs/fs-writeback.c:2270
 process_one_work+0x8a2/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaa2/0x1270 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Modules linked in:
CR2: ffffffffffffffec
---[ 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+0x362d/0x6870 fs/ext4/extents.c:4497
Code: 18 4c 8b b4 24 60 01 00 00 4d 85 f6 0f 84 b2 00 00 00 49 8d 7e 08 48 89 f8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 aa 12 00 00 <41> 0f b7 46 08 c1 e0 04 48 8d 04 40 48 89 44 24 50 49 8d 46 28 48
RSP: 0018:ffffc900041b6be0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888054df7108 RCX: ffff88802a885940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffffffffec
RBP: ffffc900041b6eb0 R08: ffffffff90af72df R09: 1ffffffff215ee5b
R10: dffffc0000000000 R11: fffffbfff215ee5c R12: dffffc0000000000
R13: 1ffff92000836dac R14: ffffffffffffffe4 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffec CR3: 000000007e770000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	18 4c 8b b4          	sbb    %cl,-0x4c(%rbx,%rcx,4)
   4:	24 60                	and    $0x60,%al
   6:	01 00                	add    %eax,(%rax)
   8:	00 4d 85             	add    %cl,-0x7b(%rbp)
   b:	f6 0f 84             	testb  $0x84,(%rdi)
   e:	b2 00                	mov    $0x0,%dl
  10:	00 00                	add    %al,(%rax)
  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 aa 12 00 00    	jne    0x12d4
* 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 50       	mov    %rax,0x50(%rsp)
  3b:	49 8d 46 28          	lea    0x28(%r14),%rax
  3f:	48                   	rex.W