[syzbot] [ocfs2?] possible deadlock in _ocfs2_free_suballoc_bits

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cc3aa43b44bd Add linux-next specific files for 20251219
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17c5b792580000
kernel config: https://syzkaller.appspot.com/x/.config?x=da1bc82c6189c463
dashboard link: https://syzkaller.appspot.com/bug?extid=73d1166b94ed9875af54
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=164b0a9a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=123c329a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/30bf539e6f28/disk-cc3aa43b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0e2f8b08e342/vmlinux-cc3aa43b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ec7ee6ece11f/bzImage-cc3aa43b.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/9340ba13ff7c/mount_0.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=144b0a9a580000)

The issue was bisected to:

commit e6f7b6feb0d2a913e28218a51d63230be2effdf2
Author: Heming Zhao <hemin...@suse.com>
Date: Fri Dec 12 07:45:03 2025 +0000

ocfs2: give ocfs2 the ability to reclaim suballocator free bg

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=120d0a22580000
final oops: https://syzkaller.appspot.com/x/report.txt?x=110d0a22580000
console output: https://syzkaller.appspot.com/x/log.txt?x=160d0a22580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+73d116...@syzkaller.appspotmail.com
Fixes: e6f7b6feb0d2 ("ocfs2: give ocfs2 the ability to reclaim suballocator free bg")

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz-executor/5944 is trying to acquire lock:
ffff88805e3ad100 (&ocfs2_sysfile_lock_key[GLOBAL_BITMAP_SYSTEM_INODE]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
ffff88805e3ad100 (&ocfs2_sysfile_lock_key[GLOBAL_BITMAP_SYSTEM_INODE]){+.+.}-{4:4}, at: _ocfs2_reclaim_suballoc_to_main fs/ocfs2/suballoc.c:2757 [inline]
ffff88805e3ad100 (&ocfs2_sysfile_lock_key[GLOBAL_BITMAP_SYSTEM_INODE]){+.+.}-{4:4}, at: _ocfs2_free_suballoc_bits+0x13f1/0x2130 fs/ocfs2/suballoc.c:2911

but task is already holding lock:
ffff88801df660e8 (&journal->j_trans_barrier){.+.+}-{4:4}, at: ocfs2_start_trans+0x36a/0x6d0 fs/ocfs2/journal.c:372

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&journal->j_trans_barrier){.+.+}-{4:4}:
down_read+0x47/0x2e0 kernel/locking/rwsem.c:1537
ocfs2_start_trans+0x36a/0x6d0 fs/ocfs2/journal.c:372
ocfs2_block_group_alloc fs/ocfs2/suballoc.c:754 [inline]
ocfs2_reserve_suballoc_bits+0x722/0x4600 fs/ocfs2/suballoc.c:903
ocfs2_reserve_new_inode+0x4f4/0xc90 fs/ocfs2/suballoc.c:1143
ocfs2_mknod+0x831/0x2030 fs/ocfs2/namei.c:307
ocfs2_mkdir+0x181/0x420 fs/ocfs2/namei.c:660
vfs_mkdir+0x414/0x630 fs/namei.c:5196
do_mkdirat+0x276/0x500 fs/namei.c:5230
__do_sys_mkdirat fs/namei.c:5252 [inline]
__se_sys_mkdirat fs/namei.c:5250 [inline]
__x64_sys_mkdirat+0x87/0xa0 fs/namei.c:5250
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (sb_internal#2){.+.+}-{0:0}:
percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline]
percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline]
__sb_start_write include/linux/fs/super.h:19 [inline]
sb_start_intwrite include/linux/fs/super.h:177 [inline]
ocfs2_start_trans+0x26b/0x6d0 fs/ocfs2/journal.c:370
ocfs2_block_group_alloc fs/ocfs2/suballoc.c:754 [inline]
ocfs2_reserve_suballoc_bits+0x722/0x4600 fs/ocfs2/suballoc.c:903
ocfs2_reserve_new_inode+0x4f4/0xc90 fs/ocfs2/suballoc.c:1143
ocfs2_mknod+0x831/0x2030 fs/ocfs2/namei.c:307
ocfs2_mkdir+0x181/0x420 fs/ocfs2/namei.c:660
vfs_mkdir+0x414/0x630 fs/namei.c:5196
do_mkdirat+0x276/0x500 fs/namei.c:5230
__do_sys_mkdirat fs/namei.c:5252 [inline]
__se_sys_mkdirat fs/namei.c:5250 [inline]
__x64_sys_mkdirat+0x87/0xa0 fs/namei.c:5250
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&ocfs2_sysfile_lock_key[GLOBAL_BITMAP_SYSTEM_INODE]){+.+.}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
inode_lock include/linux/fs.h:1028 [inline]
_ocfs2_reclaim_suballoc_to_main fs/ocfs2/suballoc.c:2757 [inline]
_ocfs2_free_suballoc_bits+0x13f1/0x2130 fs/ocfs2/suballoc.c:2911
ocfs2_free_suballoc_bits fs/ocfs2/suballoc.c:2925 [inline]
ocfs2_free_dinode+0xb1/0xe0 fs/ocfs2/suballoc.c:2940
ocfs2_remove_inode fs/ocfs2/inode.c:774 [inline]
ocfs2_wipe_inode fs/ocfs2/inode.c:896 [inline]
ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
ocfs2_evict_inode+0x1d84/0x4040 fs/ocfs2/inode.c:1299
evict+0x5f4/0xae0 fs/inode.c:837
d_delete_notify include/linux/fsnotify.h:377 [inline]
vfs_rmdir+0x427/0x6e0 fs/namei.c:5315
do_rmdir+0x281/0x500 fs/namei.c:5357
__do_sys_unlinkat fs/namei.c:5534 [inline]
__se_sys_unlinkat fs/namei.c:5528 [inline]
__x64_sys_unlinkat+0xc2/0xf0 fs/namei.c:5528
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
&ocfs2_sysfile_lock_key[GLOBAL_BITMAP_SYSTEM_INODE] --> sb_internal#2 --> &journal->j_trans_barrier

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
rlock(&journal->j_trans_barrier);
lock(sb_internal#2);
lock(&journal->j_trans_barrier);
lock(&ocfs2_sysfile_lock_key[GLOBAL_BITMAP_SYSTEM_INODE]);

*** DEADLOCK ***

8 locks held by syz-executor/5944:
#0: ffff888033eda420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff88805e3a89c0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1073 [inline]
#1: ffff88805e3a89c0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2864 [inline]
#1: ffff88805e3a89c0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2875 [inline]
#1: ffff88805e3a89c0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_rmdir+0x1be/0x500 fs/namei.c:5350
#2: ffff88802ab80bd0 (&osb->nfs_sync_rwlock){.+.+}-{4:4}, at: ocfs2_nfs_sync_lock+0x106/0x250 fs/ocfs2/dlmglue.c:2875
#3: ffff88805e3adf40 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
#3: ffff88805e3adf40 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_wipe_inode fs/ocfs2/inode.c:854 [inline]
#3: ffff88805e3adf40 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
#3: ffff88805e3adf40 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_evict_inode+0xf6c/0x4040 fs/ocfs2/inode.c:1299
#4: ffff88805e3b09c0 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
#4: ffff88805e3b09c0 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_remove_inode fs/ocfs2/inode.c:733 [inline]
#4: ffff88805e3b09c0 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_wipe_inode fs/ocfs2/inode.c:896 [inline]
#4: ffff88805e3b09c0 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
#4: ffff88805e3b09c0 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}, at: ocfs2_evict_inode+0x1507/0x4040 fs/ocfs2/inode.c:1299
#5: ffff888033eda610 (sb_internal#2){.+.+}-{0:0}, at: ocfs2_remove_inode fs/ocfs2/inode.c:742 [inline]
#5: ffff888033eda610 (sb_internal#2){.+.+}-{0:0}, at: ocfs2_wipe_inode fs/ocfs2/inode.c:896 [inline]
#5: ffff888033eda610 (sb_internal#2){.+.+}-{0:0}, at: ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
#5: ffff888033eda610 (sb_internal#2){.+.+}-{0:0}, at: ocfs2_evict_inode+0x15ea/0x4040 fs/ocfs2/inode.c:1299
#6: ffff88801df660e8 (&journal->j_trans_barrier){.+.+}-{4:4}, at: ocfs2_start_trans+0x36a/0x6d0 fs/ocfs2/journal.c:372
#7: ffff88807945a950 (jbd2_handle#2){.+.+}-{0:0}, at: start_this_handle+0x1f87/0x21c0 fs/jbd2/transaction.c:444

stack backtrace:
CPU: 0 UID: 0 PID: 5944 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043
check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
inode_lock include/linux/fs.h:1028 [inline]
_ocfs2_reclaim_suballoc_to_main fs/ocfs2/suballoc.c:2757 [inline]
_ocfs2_free_suballoc_bits+0x13f1/0x2130 fs/ocfs2/suballoc.c:2911
ocfs2_free_suballoc_bits fs/ocfs2/suballoc.c:2925 [inline]
ocfs2_free_dinode+0xb1/0xe0 fs/ocfs2/suballoc.c:2940
ocfs2_remove_inode fs/ocfs2/inode.c:774 [inline]
ocfs2_wipe_inode fs/ocfs2/inode.c:896 [inline]
ocfs2_delete_inode fs/ocfs2/inode.c:1157 [inline]
ocfs2_evict_inode+0x1d84/0x4040 fs/ocfs2/inode.c:1299
evict+0x5f4/0xae0 fs/inode.c:837
d_delete_notify include/linux/fsnotify.h:377 [inline]
vfs_rmdir+0x427/0x6e0 fs/namei.c:5315
do_rmdir+0x281/0x500 fs/namei.c:5357
__do_sys_unlinkat fs/namei.c:5534 [inline]
__se_sys_unlinkat fs/namei.c:5528 [inline]
__x64_sys_unlinkat+0xc2/0xf0 fs/namei.c:5528
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f742998ed27
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 07 01 00 00 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:00007ffe40bbd268 EFLAGS: 00000207 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 0000000000000065 RCX: 00007f742998ed27
RDX: 0000000000000200 RSI: 00007ffe40bbe410 RDI: 00000000ffffff9c
RBP: 00007f7429a13d7d R08: 000055555e6c066b R09: 0000000000000000
R10: 0000000000001000 R11: 0000000000000207 R12: 00007ffe40bbe410
R13: 00007f7429a13d7d R14: 0000000000016c75 R15: 00007ffe40bc05d0
</TASK>
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)
ocfs2: Unmounting device (7,0) on (node local)


---
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