syzbot


kernel BUG in ext4_mb_normalize_request (2)

Status: upstream: reported on 2025/12/28 01:12
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+90ae103900a7d79e46f1@syzkaller.appspotmail.com
First crash: 21d, last: 20d
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [ext4?] kernel BUG in ext4_mb_normalize_request (2) 0 (1) 2025/12/28 01:12
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 kernel BUG in ext4_mb_normalize_request -1 C 7 10d 26d 0/2 upstream: reported C repro on 2025/12/18 17:49
upstream kernel BUG in ext4_mb_normalize_request ext4 -1 2 175d 253d 0/29 auto-obsoleted due to no activity on 2025/10/30 08:12

Sample crash report:
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

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/24 01:03 upstream b927546677c8 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in ext4_mb_normalize_request
2025/12/24 12:27 upstream b927546677c8 d1b870e1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root kernel BUG in ext4_mb_normalize_request
* Struck through repros no longer work on HEAD.