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kernel BUG in ext4_mb_use_inode_pa

Status: upstream: reported C repro on 2026/02/22 04:22
Bug presence: origin:lts
[Documentation on labels]
Reported-by: syzbot+79def8a4693e93b11ce1@syzkaller.appspotmail.com
First crash: 57d, last: 9h49m
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/02/22 lts (merge base) e45d5d41c134 C [report] kernel BUG in ext4_ext_insert_extent
2026/02/22 upstream (ToT) 32a92f8c8932 C Didn't crash
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 kernel BUG in ext4_mb_use_inode_pa -1 syz 2 11d 41d 0/2 premoderation: reported syz repro on 2026/03/09 22:43
upstream kernel BUG in ext4_mb_use_inode_pa ext4 -1 C error done 2 1294d 1294d 22/29 fixed on 2023/02/24 13:50
upstream kernel BUG in ext4_mb_use_inode_pa (2) ext4 -1 C error 284 4d05h 620d 0/29 upstream: reported C repro on 2024/08/08 04:33
linux-6.1 kernel BUG in ext4_mb_use_inode_pa -1 syz error 1 40d 40d 0/3 upstream: reported syz repro on 2026/03/11 09:28
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2026/03/24 15:39 13m retest repro android13-5.15-lts report log

Sample crash report:
------------[ cut here ]------------
kernel BUG at fs/ext4/mballoc.c:4372!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 10 Comm: kworker/u4:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
RIP: 0010:ext4_mb_use_inode_pa+0x6d1/0x730 fs/ext4/mballoc.c:4372
Code: 4c 89 ff e8 51 0e ca ff 48 ba 00 00 00 00 00 fc ff df e9 be fa ff ff e8 ad df 8a ff 0f 0b e8 a6 df 8a ff 0f 0b e8 9f df 8a ff <0f> 0b e8 98 df 8a ff 0f 0b 48 8b 4d d0 80 e1 07 80 c1 03 38 c1 0f
RSP: 0018:ffffc900000a7380 EFLAGS: 00010293
RAX: ffffffff81dee741 RBX: 00000000ffffffff RCX: ffff8881002762c0
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001
RBP: ffffc900000a7408 R08: ffff88811be08000 R09: 1ffff1102418d230
R10: dffffc0000000000 R11: ffffed102418d231 R12: 1ffff1102418d234
R13: ffff888120c691a0 R14: 0000000000000020 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8363136980 CR3: 000000012f3c3000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_mb_use_preallocated+0xb3b/0xcf0 fs/ext4/mballoc.c:4470
 ext4_mb_new_blocks+0x551/0x42c0 fs/ext4/mballoc.c:5777
 ext4_ext_map_blocks+0x1722/0x61e0 fs/ext4/extents.c:4347
 ext4_map_blocks+0x988/0x1b30 fs/ext4/inode.c:674
 ext4_convert_unwritten_extents+0x2b7/0x5f0 fs/ext4/extents.c:4875
 ext4_convert_unwritten_io_end_vec+0x103/0x180 fs/ext4/extents.c:4914
 ext4_end_io_end fs/ext4/page-io.c:186 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:259 [inline]
 ext4_end_io_rsv_work+0x2c1/0x610 fs/ext4/page-io.c:273
 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325
 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472
 kthread+0x411/0x500 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Modules linked in:
---[ end trace eddb71d15e0da921 ]---
RIP: 0010:ext4_mb_use_inode_pa+0x6d1/0x730 fs/ext4/mballoc.c:4372
Code: 4c 89 ff e8 51 0e ca ff 48 ba 00 00 00 00 00 fc ff df e9 be fa ff ff e8 ad df 8a ff 0f 0b e8 a6 df 8a ff 0f 0b e8 9f df 8a ff <0f> 0b e8 98 df 8a ff 0f 0b 48 8b 4d d0 80 e1 07 80 c1 03 38 c1 0f
RSP: 0018:ffffc900000a7380 EFLAGS: 00010293
RAX: ffffffff81dee741 RBX: 00000000ffffffff RCX: ffff8881002762c0
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001
RBP: ffffc900000a7408 R08: ffff88811be08000 R09: 1ffff1102418d230
R10: dffffc0000000000 R11: ffffed102418d231 R12: 1ffff1102418d234
R13: ffff888120c691a0 R14: 0000000000000020 R15: 0000000000000002
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8363136980 CR3: 000000012f3c3000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/19 23:44 android13-5.15-lts 7fad219d720d 303e2802 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-15 kernel BUG in ext4_mb_use_inode_pa
2026/02/22 04:21 android13-5.15-lts 13d6d33696ef 6e7b5511 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-15 kernel BUG in ext4_mb_use_inode_pa
2026/03/10 15:09 android13-5.15-lts 60dba25bf158 4683d576 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 kernel BUG in ext4_mb_use_inode_pa
2026/03/06 14:48 android13-5.15-lts e714749f59d3 41d8037d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 kernel BUG in ext4_mb_use_inode_pa
2026/03/06 14:46 android13-5.15-lts e714749f59d3 41d8037d .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 kernel BUG in ext4_mb_use_inode_pa
2026/03/03 11:09 android13-5.15-lts e714749f59d3 28b83e23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-15 kernel BUG in ext4_mb_use_inode_pa
* Struck through repros no longer work on HEAD.