kernel BUG in ext4_ext_map

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	kernel BUG in ext4_ext_map_blocks ext4	-1				2	7d05h	9d05h	0/29	upstream: reported on 2026/03/01 17:40
EXT4-fs error (device loop1): ext4_ext_search_right:1612: inode #15: comm syz.1.467: pblk 257 bad header/extent: invalid extent entries - magic f30a, entries 4, max 84(84), depth 0(0)
EXT4-fs (loop1): Delayed block allocation failed for inode 15 at logical offset 110 with max blocks 2 with error 117
EXT4-fs (loop1): This should not happen!! Data will be lost
------------[ cut here ]------------
kernel BUG at fs/ext4/extents.c:2263!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 1798 Comm: syz.1.467 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:ext4_ext_find_hole fs/ext4/extents.c:2263 [inline]
RIP: 0010:ext4_ext_determine_insert_hole fs/ext4/extents.c:4076 [inline]
RIP: 0010:ext4_ext_map_blocks+0x5924/0x5dd0 fs/ext4/extents.c:4243
Code: 0f 85 49 04 00 00 e8 2b 10 99 ff e9 7d aa ff ff e8 21 10 99 ff 0f 0b e8 1a 10 99 ff 0f 0b e8 13 10 99 ff 0f 0b e8 0c 10 99 ff <0f> 0b 65 8b 05 03 6b 36 7e 89 c3 c1 e8 06 48 8d 3c c5 e8 71 c3 86
RSP: 0018:ffffc90001316e40 EFLAGS: 00010283
RAX: ffffffff81cba644 RBX: ffff88812c7ef1d0 RCX: 0000000000080000
RDX: ffffc9000196c000 RSI: 00000000000433e4 RDI: 00000000000433e5
RBP: ffffc900013170f0 R08: ffffc90001316fe7 R09: ffffc90001316fc0
R10: dffffc0000000000 R11: fffff52000262dfd R12: dffffc0000000000
R13: 0000000000000000 R14: ffff8881461de402 R15: 0000000000000054
FS:  00007fa1263f56c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f22c6e0d9c4 CR3: 000000011cf65000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ext4_map_blocks+0x3b1/0x1bd0 fs/ext4/inode.c:601
 ext4_convert_unwritten_extents+0x227/0x400 fs/ext4/extents.c:4862
 ext4_convert_unwritten_io_end_vec+0x103/0x180 fs/ext4/extents.c:4901
 ext4_put_io_end+0xc4/0x260 fs/ext4/page-io.c:310
 ext4_writepages+0x10d9/0x2eb0 fs/ext4/inode.c:2906
 do_writepages+0x128/0x280 mm/page-writeback.c:2380
 __filemap_fdatawrite_range+0x2a0/0x350 mm/filemap.c:427
 file_write_and_wait_range+0x8c/0x110 mm/filemap.c:766
 ext4_sync_file+0x1a9/0x9f0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x190/0x1a0 fs/sync.c:202
 generic_write_sync include/linux/fs.h:2920 [inline]
 ext4_buffered_write_iter+0x59b/0x640 fs/ext4/file.c:278
 ext4_file_write_iter+0x53f/0x1980 fs/ext4/file.c:-1
 call_write_iter include/linux/fs.h:2066 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x758/0xdc0 fs/read_write.c:605
 ksys_pwrite64 fs/read_write.c:712 [inline]
 __do_sys_pwrite64 fs/read_write.c:722 [inline]
 __se_sys_pwrite64 fs/read_write.c:719 [inline]
 __x64_sys_pwrite64+0x197/0x220 fs/read_write.c:719
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fa12799a799
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:00007fa1263f5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007fa127c13fa0 RCX: 00007fa12799a799
RDX: 00000000200000c1 RSI: 00002000000000c0 RDI: 0000000000000006
RBP: 00007fa127a30bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000009000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa127c14038 R14: 00007fa127c13fa0 R15: 00007ffedfcef988
Modules linked in:
---[ end trace 146158824c01c77c ]---
RIP: 0010:ext4_ext_find_hole fs/ext4/extents.c:2263 [inline]
RIP: 0010:ext4_ext_determine_insert_hole fs/ext4/extents.c:4076 [inline]
RIP: 0010:ext4_ext_map_blocks+0x5924/0x5dd0 fs/ext4/extents.c:4243
Code: 0f 85 49 04 00 00 e8 2b 10 99 ff e9 7d aa ff ff e8 21 10 99 ff 0f 0b e8 1a 10 99 ff 0f 0b e8 13 10 99 ff 0f 0b e8 0c 10 99 ff <0f> 0b 65 8b 05 03 6b 36 7e 89 c3 c1 e8 06 48 8d 3c c5 e8 71 c3 86
RSP: 0018:ffffc90001316e40 EFLAGS: 00010283
RAX: ffffffff81cba644 RBX: ffff88812c7ef1d0 RCX: 0000000000080000
RDX: ffffc9000196c000 RSI: 00000000000433e4 RDI: 00000000000433e5
RBP: ffffc900013170f0 R08: ffffc90001316fe7 R09: ffffc90001316fc0
R10: dffffc0000000000 R11: fffff52000262dfd R12: dffffc0000000000
R13: 0000000000000000 R14: ffff8881461de402 R15: 0000000000000054
FS:  00007fa1263f56c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558ab646abe8 CR3: 000000011cf65000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400