linux-kernel - Re: [syzbot] [ocfs2?] kernel BUG in ocfs2_reserve_suballoc

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Message-ID: <68f8f9e4.050a0220.346f24.0059.GAE@google.com>
Date: Wed, 22 Oct 2025 08:36:04 -0700
From: syzbot <syzbot+fd05de09d1267725aa95@...kaller.appspotmail.com>
To: dmantipov@...dex.ru, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [ocfs2?] kernel BUG in ocfs2_reserve_suballoc_bits

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
kernel BUG in ocfs2_reserve_suballoc_bits

------------[ cut here ]------------
kernel BUG at fs/ocfs2/suballoc.c:820!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5814 Comm: syz.0.16 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:ocfs2_reserve_suballoc_bits+0x3f67/0x46f0 fs/ocfs2/suballoc.c:820
Code: 24 98 00 00 00 80 e1 07 fe c1 38 c1 0f 8c a0 f0 ff ff 48 8b bc 24 98 00 00 00 e8 a4 15 79 fe e9 8e f0 ff ff e8 3a d6 11 fe 90 <0f> 0b 89 d1 80 e1 07 fe c1 38 c1 0f 8c d7 db ff ff 48 8b 7c 24 30
RSP: 0018:ffffc90002bbdca0 EFLAGS: 00010293
RAX: ffffffff83addc46 RBX: ffff888040d64fb8 RCX: ffff8880002cc900
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000000
RBP: ffffc90002bbe170 R08: ffffffff8f7c7677 R09: 1ffffffff1ef8ece
R10: dffffc0000000000 R11: fffffbfff1ef8ecf R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88804306ce00 R15: 00000000ffffffff
FS:  00007f125eda36c0(0000) GS:ffff88808d75f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f125ed80fb8 CR3: 00000000578b5000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 ocfs2_reserve_cluster_bitmap_bits+0xc4/0x1c0 fs/ocfs2/suballoc.c:1148
 ocfs2_local_alloc_reserve_for_window fs/ocfs2/localalloc.c:1106 [inline]
 ocfs2_local_alloc_slide_window fs/ocfs2/localalloc.c:1242 [inline]
 ocfs2_reserve_local_alloc_bits+0x88f/0x24b0 fs/ocfs2/localalloc.c:669
 ocfs2_reserve_clusters_with_limit+0x1be/0xba0 fs/ocfs2/suballoc.c:1182
 ocfs2_reserve_clusters fs/ocfs2/suballoc.c:1243 [inline]
 ocfs2_lock_allocators+0x2fa/0x5c0 fs/ocfs2/suballoc.c:2789
 ocfs2_write_begin_nolock+0x2279/0x4340 fs/ocfs2/aops.c:1719
 ocfs2_dio_wr_get_block+0xb6f/0x1770 fs/ocfs2/aops.c:2214
 get_more_blocks fs/direct-io.c:648 [inline]
 do_direct_IO fs/direct-io.c:936 [inline]
 __blockdev_direct_IO+0x16ff/0x3490 fs/direct-io.c:1243
 ocfs2_direct_IO+0x25f/0x2d0 fs/ocfs2/aops.c:2441
 generic_file_direct_write+0x1db/0x3e0 mm/filemap.c:4176
 __generic_file_write_iter+0x11d/0x230 mm/filemap.c:4345
 ocfs2_file_write_iter+0x157a/0x1d10 fs/ocfs2/file.c:2469
 iter_file_splice_write+0x975/0x10e0 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x101/0x160 fs/splice.c:1161
 splice_direct_to_actor+0x5a8/0xcc0 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x181/0x270 fs/splice.c:1230
 do_sendfile+0x4da/0x7e0 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64+0x13e/0x190 fs/read_write.c:1417
 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: 0033:0x7f125df8e929
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:00007f125eda3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f125e1b5fa0 RCX: 00007f125df8e929
RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000008
RBP: 00007f125e010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 000000080000000c R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f125e1b5fa0 R15: 00007fff162fbea8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ocfs2_reserve_suballoc_bits+0x3f67/0x46f0 fs/ocfs2/suballoc.c:820
Code: 24 98 00 00 00 80 e1 07 fe c1 38 c1 0f 8c a0 f0 ff ff 48 8b bc 24 98 00 00 00 e8 a4 15 79 fe e9 8e f0 ff ff e8 3a d6 11 fe 90 <0f> 0b 89 d1 80 e1 07 fe c1 38 c1 0f 8c d7 db ff ff 48 8b 7c 24 30
RSP: 0018:ffffc90002bbdca0 EFLAGS: 00010293
RAX: ffffffff83addc46 RBX: ffff888040d64fb8 RCX: ffff8880002cc900
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 0000000000000000
RBP: ffffc90002bbe170 R08: ffffffff8f7c7677 R09: 1ffffffff1ef8ece
R10: dffffc0000000000 R11: fffffbfff1ef8ecf R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88804306ce00 R15: 00000000ffffffff
FS:  00007f125eda36c0(0000) GS:ffff88808d75f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f125ed80fb8 CR3: 00000000578b5000 CR4: 0000000000352ef0


Tested on:

commit:         552c5071 Merge tag 'vfio-v6.18-rc3' of https://github...
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=154c3734580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cb89820a01e5d251
dashboard link: https://syzkaller.appspot.com/bug?extid=fd05de09d1267725aa95
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=13d43734580000