EXT4-fs error (device loop0): __ext4_ext_dirty:206: inode #12: comm syz.0.2252: mark_inode_dirty error BUG: unable to handle page fault for address: fffffffffffffffc #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD cf35067 P4D cf35067 PUD cf37067 PMD 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 13541 Comm: syz.0.2252 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+0x2d11/0x6800 fs/ext4/extents.c:4498 Code: 8b 7c 24 10 4d 85 ff 0f 84 bd 00 00 00 e8 f7 e0 58 ff 49 8d 7f 08 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 3d 1e 00 00 <41> 0f b7 47 08 c1 e0 04 48 8d 04 40 48 89 44 24 08 4d 89 fc 49 8d RSP: 0018:ffffc900048aed20 EFLAGS: 00010246 RAX: 0000000000000000 RBX: fffffffffffffff4 RCX: 0000000000080000 RDX: ffffc9000e22f000 RSI: 000000000001fe91 RDI: fffffffffffffffc RBP: ffffc900048aefd0 R08: ffff88807ef53c00 R09: 0000000000000002 R10: 00000000ffffffe4 R11: 0000000000000002 R12: 0000000000000001 R13: 1ffff92000915dd0 R14: dffffc0000000000 R15: fffffffffffffff4 FS: 00007f03fa2ec6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffffffffffc CR3: 000000006a739000 CR4: 00000000003506f0 Call Trace: ext4_map_blocks+0x9e2/0x1b80 fs/ext4/inode.c:654 _ext4_get_block+0x1eb/0x480 fs/ext4/inode.c:796 __block_write_begin_int+0x57f/0x1af0 fs/buffer.c:2124 block_page_mkwrite+0x2b2/0x4c0 fs/buffer.c:2643 ext4_page_mkwrite+0x4d9/0x1220 fs/ext4/inode.c:6337 do_page_mkwrite+0x153/0x3e0 mm/memory.c:2951 do_shared_fault mm/memory.c:4717 [inline] do_fault mm/memory.c:4779 [inline] do_pte_missing mm/memory.c:3689 [inline] handle_pte_fault mm/memory.c:5047 [inline] __handle_mm_fault mm/memory.c:5188 [inline] handle_mm_fault+0x1ab4/0x4c00 mm/memory.c:5353 do_user_addr_fault+0x730/0x12c0 arch/x86/mm/fault.c:1371 handle_page_fault arch/x86/mm/fault.c:1463 [inline] exc_page_fault+0x64/0x100 arch/x86/mm/fault.c:1516 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608 RIP: 0010:rep_movs_alternative+0x4a/0x90 arch/x86/lib/copy_user_64.S:71 Code: 75 f1 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 8b 06 48 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 df 83 f9 08 73 e8 eb c9 a4 c3 48 8b 06 48 89 07 48 8d 47 08 48 83 e0 f8 48 29 f8 48 01 RSP: 0018:ffffc900048af958 EFLAGS: 00050206 RAX: ffffffff8427b901 RBX: 1ffff92000915fb7 RCX: 0000000000000240 RDX: 0000000000000000 RSI: ffff88805cafadc0 RDI: 0000200000002000 RBP: ffffc900048afab8 R08: ffff88805cafafff R09: 1ffff1100b95f5ff R10: dffffc0000000000 R11: ffffed100b95f600 R12: ffff88805cafa000 R13: 0000000000001000 R14: 0000000000001000 R15: ffffc900048afdc8 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline] raw_copy_to_user arch/x86/include/asm/uaccess_64.h:133 [inline] copyout lib/iov_iter.c:168 [inline] _copy_to_iter+0x24f/0x1120 lib/iov_iter.c:316 copy_page_to_iter+0xa7/0x150 lib/iov_iter.c:481 copy_folio_to_iter include/linux/uio.h:185 [inline] filemap_read+0x838/0xf00 mm/filemap.c:2750 call_read_iter include/linux/fs.h:2012 [inline] new_sync_read fs/read_write.c:389 [inline] vfs_read+0x46a/0x970 fs/read_write.c:470 ksys_read+0x150/0x260 fs/read_write.c:613 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f03f939cdd9 Code: ff c3 66 2e 0f 1f 84 00 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 RSP: 002b:00007f03fa2ec028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f03f9616090 RCX: 00007f03f939cdd9 RDX: 0000000000002020 RSI: 0000200000001240 RDI: 0000000000000005 RBP: 00007f03f9432d69 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f03f9616128 R14: 00007f03f9616090 R15: 00007ffda606bf78 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+0x2d11/0x6800 fs/ext4/extents.c:4498 Code: 8b 7c 24 10 4d 85 ff 0f 84 bd 00 00 00 e8 f7 e0 58 ff 49 8d 7f 08 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 3d 1e 00 00 <41> 0f b7 47 08 c1 e0 04 48 8d 04 40 48 89 44 24 08 4d 89 fc 49 8d RSP: 0018:ffffc900048aed20 EFLAGS: 00010246 RAX: 0000000000000000 RBX: fffffffffffffff4 RCX: 0000000000080000 RDX: ffffc9000e22f000 RSI: 000000000001fe91 RDI: fffffffffffffffc RBP: ffffc900048aefd0 R08: ffff88807ef53c00 R09: 0000000000000002 R10: 00000000ffffffe4 R11: 0000000000000002 R12: 0000000000000001 R13: 1ffff92000915dd0 R14: dffffc0000000000 R15: fffffffffffffff4 FS: 00007f03fa2ec6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffffffffffc CR3: 000000006a739000 CR4: 00000000003506f0 ---------------- Code disassembly (best guess): 0: 8b 7c 24 10 mov 0x10(%rsp),%edi 4: 4d 85 ff test %r15,%r15 7: 0f 84 bd 00 00 00 je 0xca d: e8 f7 e0 58 ff call 0xff58e109 12: 49 8d 7f 08 lea 0x8(%r15),%rdi 16: 48 89 f8 mov %rdi,%rax 19: 48 c1 e8 03 shr $0x3,%rax 1d: 42 0f b6 04 30 movzbl (%rax,%r14,1),%eax 22: 84 c0 test %al,%al 24: 0f 85 3d 1e 00 00 jne 0x1e67 * 2a: 41 0f b7 47 08 movzwl 0x8(%r15),%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: 4d 89 fc mov %r15,%r12 3e: 49 rex.WB 3f: 8d .byte 0x8d