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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: 84d, last: 1d08h
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 8 6h56m 75d 0/29 upstream: reported on 2025/12/28 01:12
android-5-15 kernel BUG in ext4_mb_normalize_request origin:lts -1 C 6 8d16h 9d13h 0/2 upstream: reported C repro on 2026/03/03 12:10
upstream kernel BUG in ext4_mb_normalize_request ext4 -1 2 233d 311d 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:
------------[ cut here ]------------
kernel BUG at fs/ext4/mballoc.c:3729!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 49 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
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:ffffc900009e7410 EFLAGS: 00010293
RAX: ffffffff81d40fb1 RBX: 0000000000000060 RCX: ffff888101ffbb40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffffc900009e74f0 R08: ffff888129c1e86f R09: 1ffff11025383d0d
R10: dffffc0000000000 R11: ffffed1025383d0e R12: ffff888120f2cb60
R13: dffffc0000000000 R14: 0000000000000000 R15: 000000000000001f
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000340bf CR3: 000000010ac21000 CR4: 00000000003506a0
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_end_io_end fs/ext4/page-io.c:189 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:262 [inline]
 ext4_end_io_rsv_work+0x2c1/0x610 fs/ext4/page-io.c:276
 process_one_work+0x6e1/0xba0 kernel/workqueue.c:2301
 worker_thread+0xa6a/0x13c0 kernel/workqueue.c:2447
 kthread+0x346/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Modules linked in:
---[ end trace 61c386cae9c7a2cb ]---
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:ffffc900009e7410 EFLAGS: 00010293
RAX: ffffffff81d40fb1 RBX: 0000000000000060 RCX: ffff888101ffbb40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffffc900009e74f0 R08: ffff888129c1e86f R09: 1ffff11025383d0d
R10: dffffc0000000000 R11: ffffed1025383d0e R12: ffff888120f2cb60
R13: dffffc0000000000 R14: 0000000000000000 R15: 000000000000001f
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f36fe8c7ff8 CR3: 000000010ed2d000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/04 17:09 android13-5.10-lts dad37bbb13a8 e6b6b96b .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
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
2026/03/11 17:39 android13-5.10-lts 9136079e403a 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2026/03/05 23:22 android13-5.10-lts dad37bbb13a8 d20b04c8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 kernel BUG in ext4_mb_normalize_request
2026/03/05 14:00 android13-5.10-lts dad37bbb13a8 d20b04c8 .config console log report info [disk image] [vmlinux] [kernel image] 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.