Message-ID: <69202d58.a70a0220.2ea503.004a.GAE@google.com>
Date: Fri, 21 Nov 2025 01:14:00 -0800
From: syzbot ci <syzbot+cib6a48fc441f958bd@...kaller.appspotmail.com>
To: adilger.kernel@...ger.ca, albinbabuvarghese20@...il.com, 
	david.hunter.linux@...il.com, eraykrdg1@...il.com, linux-ext4@...r.kernel.org, 
	linux-kernel@...r.kernel.org, skhan@...uxfoundation.org, 
	syzbot@...kaller.appspotmail.com, tytso@....edu
Cc: syzbot@...ts.linux.dev, syzkaller-bugs@...glegroups.com
Subject: [syzbot ci] Re: ext4: fix unaligned preallocation with bigalloc

syzbot ci has tested the following series

[v1] ext4: fix unaligned preallocation with bigalloc
https://lore.kernel.org/all/20251121002209.416949-2-eraykrdg1@gmail.com
* [PATCH] ext4: fix unaligned preallocation with bigalloc

and found the following issue:
kernel BUG in ext4_mb_new_inode_pa

Full report is available here:
https://ci.syzbot.org/series/5fbb06a2-0d5c-4936-94b6-d73abad55373

***

kernel BUG in ext4_mb_new_inode_pa

tree:      torvalds
URL:       https://kernel.googlesource.com/pub/scm/linux/kernel/git/torvalds/linux
base:      23cb64fb76257309e396ea4cec8396d4a1dbae68
arch:      amd64
compiler:  Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
config:    https://ci.syzbot.org/builds/3beb0e0f-6449-481d-8a5c-870149d28caf/config
C repro:   https://ci.syzbot.org/findings/891b93f7-ef7e-4890-8c4b-ed438fa3fa28/c_repro
syz repro: https://ci.syzbot.org/findings/891b93f7-ef7e-4890-8c4b-ed438fa3fa28/syz_repro

loop0: detected capacity change from 0 to 1024
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
------------[ cut here ]------------
kernel BUG at fs/ext4/mballoc.c:5312!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 5990 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:ext4_mb_new_inode_pa+0x144e/0x1520 fs/ext4/mballoc.c:5312
Code: 5d 04 00 eb 2c e8 42 d8 43 ff 90 0f 0b e8 3a d8 43 ff 90 0f 0b e8 32 d8 43 ff eb 3c e8 2b d8 43 ff 90 0f 0b e8 23 d8 43 ff 90 <0f> 0b e8 1b d8 43 ff 31 f6 65 ff 0d 82 24 f2 0f 0f 94 c3 40 0f 94
RSP: 0018:ffffc900037c6a88 EFLAGS: 00010293
RAX: ffffffff827c2b9d RBX: 0000000000000201 RCX: ffff8881ba628000
RDX: 0000000000000000 RSI: 0000000000000201 RDI: 0000000000000210
RBP: 0000000000000190 R08: ffffea000418ec37 R09: 1ffffd4000831d86
R10: dffffc0000000000 R11: fffff94000831d87 R12: 0000000000000004
R13: ffff88801b03f2b8 R14: dffffc0000000000 R15: 0000000000000210
FS:  0000555557696500(0000) GS:ffff88818eb3b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f863fff CR3: 000000016b520000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 ext4_mb_try_best_found+0x33e/0x440 fs/ext4/mballoc.c:2389
 ext4_mb_regular_allocator+0x9fa/0x2970 fs/ext4/mballoc.c:3040
 ext4_mb_new_blocks+0xd11/0x4720 fs/ext4/mballoc.c:6319
 ext4_ext_map_blocks+0x161a/0x6ac0 fs/ext4/extents.c:4383
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x860/0x1740 fs/ext4/inode.c:811
 _ext4_get_block+0x200/0x4c0 fs/ext4/inode.c:910
 ext4_get_block_unwritten+0x2e/0x100 fs/ext4/inode.c:943
 ext4_block_write_begin+0x993/0x1710 fs/ext4/inode.c:1198
 ext4_write_begin+0xc04/0x19a0 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x445/0xda0 fs/ext4/inode.c:3129
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4254
 ext4_buffered_write_iter+0xce/0x3a0 fs/ext4/file.c:299
 ext4_file_write_iter+0x298/0x1bc0 fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5c9/0xb30 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+0x193/0x220 fs/read_write.c:798
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3f2c38f6c9
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:00007fff15880d18 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f3f2c5e5fa0 RCX: 00007f3f2c38f6c9
RDX: 0000000000000001 RSI: 00002000000005c0 RDI: 0000000000000004
RBP: 00007f3f2c411f91 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000004fed0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3f2c5e5fa0 R14: 00007f3f2c5e5fa0 R15: 0000000000000004
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_mb_new_inode_pa+0x144e/0x1520 fs/ext4/mballoc.c:5312
Code: 5d 04 00 eb 2c e8 42 d8 43 ff 90 0f 0b e8 3a d8 43 ff 90 0f 0b e8 32 d8 43 ff eb 3c e8 2b d8 43 ff 90 0f 0b e8 23 d8 43 ff 90 <0f> 0b e8 1b d8 43 ff 31 f6 65 ff 0d 82 24 f2 0f 0f 94 c3 40 0f 94
RSP: 0018:ffffc900037c6a88 EFLAGS: 00010293
RAX: ffffffff827c2b9d RBX: 0000000000000201 RCX: ffff8881ba628000
RDX: 0000000000000000 RSI: 0000000000000201 RDI: 0000000000000210
RBP: 0000000000000190 R08: ffffea000418ec37 R09: 1ffffd4000831d86
R10: dffffc0000000000 R11: fffff94000831d87 R12: 0000000000000004
R13: ffff88801b03f2b8 R14: dffffc0000000000 R15: 0000000000000210
FS:  0000555557696500(0000) GS:ffff88818eb3b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2f863fff CR3: 000000016b520000 CR4: 00000000000006f0


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
  Tested-by: syzbot@...kaller.appspotmail.com

---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@...glegroups.com.

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