syzbot


kernel BUG in ext4_mb_normalize_request

Status: upstream: reported C repro on 2025/12/18 17:49
Reported-by: syzbot+16dfafdbe48358333904@syzkaller.appspotmail.com
First crash: 75d, last: 16h41m
Fix bisection: the issue occurs on the latest tested release (bisect log)
  
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in ext4_mb_normalize_request (2) ext4 -1 7 7d16h 66d 0/29 upstream: reported on 2025/12/28 01:12
android-5-15 kernel BUG in ext4_mb_normalize_request origin:lts -1 C 5 3h57m 20h37m 0/2 upstream: reported C repro on 2026/03/03 12:10
upstream kernel BUG in ext4_mb_normalize_request ext4 -1 2 225d 302d 0/29 auto-obsoleted due to no activity on 2025/10/30 08:12
Last patch testing requests (6)
Created Duration User Patch Repo Result
2026/01/18 15:24 13m retest repro android13-5.10-lts error
2026/01/03 14:36 16m retest repro android13-5.10-lts report log
2026/01/03 14:36 18m retest repro android13-5.10-lts report log
2026/01/03 14:36 8m retest repro android13-5.10-lts report log
2026/01/03 14:36 9m retest repro android13-5.10-lts report log
2026/01/03 14:36 10m retest repro android13-5.10-lts report log

Sample crash report:
EXT4-fs error (device loop2): ext4_mb_release_inode_pa:4375: group 0, free 0, pa_free 1
EXT4-fs error (device loop2): ext4_find_extent:928: inode #15: comm syz.2.69: pblk 257 bad header/extent: invalid extent entries - magic f30a, entries 4, max 84(84), depth 0(0)
EXT4-fs (loop2): Delayed block allocation failed for inode 15 at logical offset 119 with max blocks 1 with error 117
EXT4-fs (loop2): This should not happen!! Data will be lost
------------[ cut here ]------------
kernel BUG at fs/ext4/mballoc.c:3729!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 694 Comm: syz.2.69 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:ext4_mb_normalize_request+0x1291/0x12e0 fs/ext4/mballoc.c:3729
Code: ff ff 48 8b 7d a8 e8 ae 27 cb ff e9 6b fc ff ff e8 b4 a6 90 ff 0f 0b e8 ad a6 90 ff 0f 0b e8 a6 a6 90 ff 0f 0b e8 9f a6 90 ff <0f> 0b e8 98 a6 90 ff 0f 0b e8 91 a6 90 ff 48 8b 85 78 ff ff ff 42
RSP: 0018:ffffc90001e96b90 EFLAGS: 00010293
RAX: ffffffff81d40fb1 RBX: 0000000000000070 RCX: ffff88810d5513c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffffc90001e96c70 R08: ffff88812ca806ef R09: 1ffff110259500dd
R10: dffffc0000000000 R11: ffffed10259500de R12: ffff88812ca4a7f0
R13: dffffc0000000000 R14: 0000000000000000 R15: 000000000000003b
FS:  00007f0f58aa86c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000340bf CR3: 0000000126a11000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ext4_mb_new_blocks+0xc31/0x4340 fs/ext4/mballoc.c:5249
 ext4_ext_map_blocks+0x1679/0x5dd0 fs/ext4/extents.c:4335
 ext4_map_blocks+0x985/0x1bd0 fs/ext4/inode.c:674
 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: 0033:0x7f0f58c45799
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:00007f0f58aa8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f0f58ebefa0 RCX: 00007f0f58c45799
RDX: 00000000200000c1 RSI: 00002000000000c0 RDI: 0000000000000006
RBP: 00007f0f58cdbbd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000009000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0f58ebf038 R14: 00007f0f58ebefa0 R15: 00007fff3ec97078
Modules linked in:
---[ end trace efc32919fbfe4861 ]---
RIP: 0010:ext4_mb_normalize_request+0x1291/0x12e0 fs/ext4/mballoc.c:3729
Code: ff ff 48 8b 7d a8 e8 ae 27 cb ff e9 6b fc ff ff e8 b4 a6 90 ff 0f 0b e8 ad a6 90 ff 0f 0b e8 a6 a6 90 ff 0f 0b e8 9f a6 90 ff <0f> 0b e8 98 a6 90 ff 0f 0b e8 91 a6 90 ff 48 8b 85 78 ff ff ff 42
RSP: 0018:ffffc90001e96b90 EFLAGS: 00010293
RAX: ffffffff81d40fb1 RBX: 0000000000000070 RCX: ffff88810d5513c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffffc90001e96c70 R08: ffff88812ca806ef R09: 1ffff110259500dd
R10: dffffc0000000000 R11: ffffed10259500de R12: ffff88812ca4a7f0
R13: dffffc0000000000 R14: 0000000000000000 R15: 000000000000003b
FS:  00007f0f58aa86c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000340bf CR3: 0000000126a11000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/03 16:06 android13-5.10-lts dad37bbb13a8 4180d919 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2025/12/19 19:01 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2025/12/19 09:38 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2025/12/19 06:51 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2025/12/18 17:40 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2026/03/03 15:10 android13-5.10-lts dad37bbb13a8 4180d919 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2025/12/20 07:34 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2025/12/20 05:29 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2025/12/18 13:29 android13-5.10-lts e253c52bbdfc d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
* Struck through repros no longer work on HEAD.