[syzbot] [ocfs2?] kernel BUG in __ocfs2_claim_clusters

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 98ac9cc4b445 Merge tag 'f2fs-fix-6.18-rc2' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1754ede2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c2d7b4143707d3a0
dashboard link: https://syzkaller.appspot.com/bug?extid=d937c5714fc8cd6d39df
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-98ac9cc4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4a2afc96e189/vmlinux-98ac9cc4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/92d24cde05de/bzImage-98ac9cc4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d937c5...@syzkaller.appspotmail.com

(syz.0.0,5328,0):ocfs2_read_blocks_sync:112 ERROR: status = -12
(syz.0.0,5328,0):update_backups:196 ERROR: status = -12
ocfs2: Failed to update super blocks on 7,0 during fs resize. This condition is not fatal, but fsck.ocfs2 should be run to fix it
------------[ cut here ]------------
kernel BUG at fs/ocfs2/suballoc.c:2390!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5328 Comm: syz.0.0 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_claim_clusters+0x8d1/0x8f0 fs/ocfs2/suballoc.c:2390
Code: db 78 fe e9 9b fc ff ff e8 3c a2 11 fe 48 c7 c7 a0 a6 66 8e 48 89 de 4c 89 fa e8 ea 7c 1c 01 e9 a2 fc ff ff e8 20 a2 11 fe 90 <0f> 0b e8 18 a2 11 fe 90 0f 0b e8 10 a2 11 fe 90 0f 0b e8 08 a2 11
RSP: 0018:ffffc9000d3ae8c0 EFLAGS: 00010283
RAX: ffffffff83aeb170 RBX: 1ffff110024f0010 RCX: 0000000000100000
RDX: ffffc9000e7eb000 RSI: 00000000000823b8 RDI: 00000000000823b9
RBP: ffffc9000d3aea50 R08: ffffc9000d3ae967 R09: 0000000000000000
R10: ffffc9000d3ae940 R11: fffff52001a75d2d R12: 0000000000000000
R13: ffff888033b90000 R14: 0000000000000000 R15: ffff888012780080
FS: 00007f6b80dd76c0(0000) GS:ffff88808d300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000012d000 CR3: 00000000428be000 CR4: 0000000000352ef0
Call Trace:
<TASK>
ocfs2_claim_clusters fs/ocfs2/suballoc.c:2458 [inline]
ocfs2_block_group_alloc_contig fs/ocfs2/suballoc.c:432 [inline]
ocfs2_block_group_alloc fs/ocfs2/suballoc.c:699 [inline]
ocfs2_reserve_suballoc_bits+0xf1e/0x4640 fs/ocfs2/suballoc.c:834
ocfs2_reserve_new_metadata_blocks+0x403/0x940 fs/ocfs2/suballoc.c:984
ocfs2_reserve_new_metadata fs/ocfs2/suballoc.c:1027 [inline]
ocfs2_lock_allocators+0x29e/0x5c0 fs/ocfs2/suballoc.c:2761
ocfs2_write_begin_nolock+0x2279/0x4340 fs/ocfs2/aops.c:1719
ocfs2_write_begin+0x1bb/0x310 fs/ocfs2/aops.c:1884
generic_perform_write+0x2c5/0x900 mm/filemap.c:4242
ocfs2_file_write_iter+0x157a/0x1d10 fs/ocfs2/file.c:2469
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x5c9/0xb30 fs/read_write.c:686
ksys_write+0x145/0x250 fs/read_write.c:738
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: 0033:0x7f6b7ff8efc9
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:00007f6b80dd7038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f6b801e6090 RCX: 00007f6b7ff8efc9
RDX: 00000000fffffec6 RSI: 0000200000000180 RDI: 000000000000000d
RBP: 00007f6b80011f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6b801e6128 R14: 00007f6b801e6090 R15: 00007ffd51891f88
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__ocfs2_claim_clusters+0x8d1/0x8f0 fs/ocfs2/suballoc.c:2390
Code: db 78 fe e9 9b fc ff ff e8 3c a2 11 fe 48 c7 c7 a0 a6 66 8e 48 89 de 4c 89 fa e8 ea 7c 1c 01 e9 a2 fc ff ff e8 20 a2 11 fe 90 <0f> 0b e8 18 a2 11 fe 90 0f 0b e8 10 a2 11 fe 90 0f 0b e8 08 a2 11
RSP: 0018:ffffc9000d3ae8c0 EFLAGS: 00010283
RAX: ffffffff83aeb170 RBX: 1ffff110024f0010 RCX: 0000000000100000
RDX: ffffc9000e7eb000 RSI: 00000000000823b8 RDI: 00000000000823b9
RBP: ffffc9000d3aea50 R08: ffffc9000d3ae967 R09: 0000000000000000
R10: ffffc9000d3ae940 R11: fffff52001a75d2d R12: 0000000000000000
R13: ffff888033b90000 R14: 0000000000000000 R15: ffff888012780080
FS: 00007f6b80dd76c0(0000) GS:ffff88808d300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000012d000 CR3: 00000000428be000 CR4: 0000000000352ef0


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 05c93f3395ed Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=111f21b4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=3b5338ad1e59a06c

dashboard link: https://syzkaller.appspot.com/bug?extid=d937c5714fc8cd6d39df
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11b4661a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=102c5592580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6b5c913e373c/disk-05c93f33.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/15e75f1266ef/vmlinux-05c93f33.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd930129c578/Image-05c93f33.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d7f8cb828f94/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=16b4661a580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d937c5...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
ocfs2: Mounting device (7,0) on (node local, slot 0) with writeback data mode.

------------[ cut here ]------------
kernel BUG at fs/ocfs2/suballoc.c:2390!

Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
Modules linked in:
CPU: 0 UID: 0 PID: 6742 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __ocfs2_claim_clusters+0x768/0x7c4 fs/ocfs2/suballoc.c:2390
lr : __ocfs2_claim_clusters+0x768/0x7c4 fs/ocfs2/suballoc.c:2390
sp : ffff8000a1706a60
x29: ffff8000a1706ba0 x28: 0000000000000040 x27: 0000000000000040
x26: dfff800000000000 x25: 1fffe00018d35af0 x24: ffff0000c69ad780
x23: 0000000000000039 x22: ffff0000da3ec000 x21: 0000000000000000
x20: ffff0000c69ad798 x19: ffff7000142e0d54 x18: 1fffe000337d4a90
x17: ffff800093335000 x16: ffff80008ad6b188 x15: 0000000000000005
x14: 1ffff000142e0d58 x13: 0000000000000000 x12: 0000000000000000
x11: ffff7000142e0d5d x10: 0000000000ff0100 x9 : 0000000000000000
x8 : ffff0000c8278000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffff8000a1706d90 x4 : 0000000000000000 x3 : 0000000000000020
x2 : 0000000000000008 x1 : 0000000000000040 x0 : 0000000000000040
Call trace:
__ocfs2_claim_clusters+0x768/0x7c4 fs/ocfs2/suballoc.c:2390 (P)
ocfs2_claim_clusters fs/ocfs2/suballoc.c:2458 [inline]
ocfs2_block_group_claim_bits fs/ocfs2/suballoc.c:474 [inline]
ocfs2_block_group_grow_discontig fs/ocfs2/suballoc.c:515 [inline]
ocfs2_block_group_alloc_discontig fs/ocfs2/suballoc.c:641 [inline]
ocfs2_block_group_alloc fs/ocfs2/suballoc.c:703 [inline]
ocfs2_reserve_suballoc_bits+0x1b64/0x3b9c fs/ocfs2/suballoc.c:834
ocfs2_reserve_new_inode+0x3c0/0xac0 fs/ocfs2/suballoc.c:1074
ocfs2_mknod+0x710/0x1cf0 fs/ocfs2/namei.c:306
ocfs2_create+0x190/0x474 fs/ocfs2/namei.c:676
lookup_open fs/namei.c:3796 [inline]
open_last_lookups fs/namei.c:3895 [inline]
path_openat+0x12d8/0x2c40 fs/namei.c:4131
do_filp_open+0x18c/0x36c fs/namei.c:4161
do_sys_openat2+0x11c/0x1b4 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__arm64_sys_openat+0x120/0x158 fs/open.c:1463
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49
el0_svc_common+0xe8/0x23c arch/arm64/kernel/syscall.c:132
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:724
el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
Code: aa1803e2 94384723 17ffff3d 97951fa1 (d4210000)

---[ end trace 0000000000000000 ]---

---
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[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.