[syzbot] [ext4?] kernel BUG in ext4_mb_normalize_request (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b927546677c8 Merge tag 'dma-mapping-6.19-2025-12-22' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15344b92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1f2b6fe1fdf1a00b
dashboard link: https://syzkaller.appspot.com/bug?extid=90ae103900a7d79e46f1
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ddac8d425533/disk-b9275466.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6d9161401879/vmlinux-b9275466.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dc4982f21fd4/bzImage-b9275466.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+90ae10...@syzkaller.appspotmail.com

EXT4-fs (loop2): start 0, size 131072, fe_logical 131072
------------[ cut here ]------------
kernel BUG at fs/ext4/mballoc.c:4657!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 6131 Comm: syz.2.37 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:ext4_mb_normalize_request+0x1cd8/0x1d10 fs/ext4/mballoc.c:4657
Code: 71 ae ff 48 8b 44 24 38 48 8b 38 48 c7 c6 80 bc fe 8a 48 c7 c2 e0 d2 fe 8a 48 8b 4c 24 28 4d 89 f0 49 89 d9 e8 19 f5 09 00 90 <0f> 0b e8 f1 3a 4c ff 90 0f 0b e8 e9 3a 4c ff 90 0f 0b e8 e1 3a 4c
RSP: 0018:ffffc9000613ed20 EFLAGS: 00010246
RAX: f56237077cb2d800 RBX: 0000000000020000 RCX: f56237077cb2d800
RDX: ffffc9000ff71000 RSI: 0000000000000674 RDI: 0000000000000675
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000c27d2d R12: ffffffff00020800
R13: dffffc0000000000 R14: 0000000000020000 R15: 0000000000020000
FS: 00007f17dd9456c0(0000) GS:ffff888126def000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110f246add CR3: 000000002897a000 CR4: 00000000003526f0
Call Trace:
<TASK>
ext4_mb_new_blocks+0xc46/0x46b0 fs/ext4/mballoc.c:6310
ext4_ext_map_blocks+0x1877/0x69c0 fs/ext4/extents.c:4383
ext4_map_create_blocks fs/ext4/inode.c:613 [inline]
ext4_map_blocks+0x82c/0x16f0 fs/ext4/inode.c:816
_ext4_get_block+0x1fa/0x4c0 fs/ext4/inode.c:916
ext4_block_write_begin+0xb03/0x1940 fs/ext4/inode.c:1203
ext4_write_begin+0xb3a/0x1870 fs/ext4/ext4_jbd2.h:-1
ext4_da_write_begin+0x352/0xd30 fs/ext4/inode.c:3130
generic_perform_write+0x29d/0x8c0 mm/filemap.c:4314
ext4_buffered_write_iter+0xd0/0x3a0 fs/ext4/file.c:299
ext4_file_write_iter+0x293/0x1be0 fs/ext4/file.c:-1
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x5d5/0xb40 fs/read_write.c:686
ksys_pwrite64 fs/read_write.c:793 [inline]
__do_sys_pwrite64 fs/read_write.c:801 [inline]
__se_sys_pwrite64 fs/read_write.c:798 [inline]
__x64_sys_pwrite64+0x196/0x220 fs/read_write.c:798
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: 0033:0x7f17df6ff749
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:00007f17dd945038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f17df956090 RCX: 00007f17df6ff749
RDX: 0000000000000001 RSI: 0000200000000140 RDI: 0000000000000008
RBP: 00007f17df783f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000008000c61 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f17df956128 R14: 00007f17df956090 R15: 00007ffdca7c0738
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_mb_normalize_request+0x1cd8/0x1d10 fs/ext4/mballoc.c:4657
Code: 71 ae ff 48 8b 44 24 38 48 8b 38 48 c7 c6 80 bc fe 8a 48 c7 c2 e0 d2 fe 8a 48 8b 4c 24 28 4d 89 f0 49 89 d9 e8 19 f5 09 00 90 <0f> 0b e8 f1 3a 4c ff 90 0f 0b e8 e9 3a 4c ff 90 0f 0b e8 e1 3a 4c
RSP: 0018:ffffc9000613ed20 EFLAGS: 00010246
RAX: f56237077cb2d800 RBX: 0000000000020000 RCX: f56237077cb2d800
RDX: ffffc9000ff71000 RSI: 0000000000000674 RDI: 0000000000000675
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff52000c27d2d R12: ffffffff00020800
R13: dffffc0000000000 R14: 0000000000020000 R15: 0000000000020000
FS: 00007f17dd9456c0(0000) GS:ffff888126def000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110f246add CR3: 000000002897a000 CR4: 00000000003526f0


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