[syzbot] [ocfs2?] possible deadlock in ocfs2_nfs_sync_lock (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cbf33b8e0b36 Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=177ec458580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1b4263e12240e6e1
dashboard link: https://syzkaller.appspot.com/bug?extid=961597646899ae06073f
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-cbf33b8e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/54786e46ef23/vmlinux-cbf33b8e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd6f88ce083b/bzImage-cbf33b8e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+961597...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kswapd0/77 is trying to acquire lock:
ffff888032ee4bd0 (&osb->nfs_sync_rwlock){.+.+}-{4:4}, at: ocfs2_nfs_sync_lock+0x106/0x250 fs/ocfs2/dlmglue.c:2875

but task is already holding lock:
ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7015 [inline]
ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x951/0x2800 mm/vmscan.c:7389

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (fs_reclaim){+.+.}-{0:0}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__fs_reclaim_acquire mm/page_alloc.c:4269 [inline]
fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4283
might_alloc include/linux/sched/mm.h:318 [inline]
slab_pre_alloc_hook mm/slub.c:4897 [inline]
slab_alloc_node mm/slub.c:5221 [inline]
__kmalloc_cache_noprof+0x40/0x6f0 mm/slub.c:5719
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
ocfs2_reserve_new_metadata_blocks+0x113/0x940 fs/ocfs2/suballoc.c:968
ocfs2_mknod+0xe08/0x2050 fs/ocfs2/namei.c:350
ocfs2_mkdir+0x191/0x440 fs/ocfs2/namei.c:659
vfs_mkdir+0x303/0x510 fs/namei.c:4453
do_mkdirat+0x247/0x590 fs/namei.c:4486
__do_sys_mkdirat fs/namei.c:4503 [inline]
__se_sys_mkdirat fs/namei.c:4501 [inline]
__x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4501
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
inode_lock include/linux/fs.h:979 [inline]
ocfs2_remove_inode fs/ocfs2/inode.c:731 [inline]
ocfs2_wipe_inode fs/ocfs2/inode.c:894 [inline]
ocfs2_delete_inode fs/ocfs2/inode.c:1155 [inline]
ocfs2_evict_inode+0x153d/0x4100 fs/ocfs2/inode.c:1295
evict+0x504/0x9c0 fs/inode.c:810
ocfs2_dentry_iput+0x247/0x370 fs/ocfs2/dcache.c:407
__dentry_kill+0x209/0x660 fs/dcache.c:669
dput+0x19f/0x2b0 fs/dcache.c:911
ovl_check_rename_whiteout fs/overlayfs/super.c:619 [inline]
ovl_make_workdir fs/overlayfs/super.c:714 [inline]
ovl_get_workdir+0xac3/0x17b0 fs/overlayfs/super.c:837
ovl_fill_super+0x154a/0x3da0 fs/overlayfs/super.c:1468
vfs_get_super fs/super.c:1324 [inline]
get_tree_nodev+0xb8/0x150 fs/super.c:1343
vfs_get_tree+0x8f/0x2b0 fs/super.c:1751
fc_mount fs/namespace.c:1208 [inline]
do_new_mount_fc fs/namespace.c:3651 [inline]
do_new_mount+0x302/0xa10 fs/namespace.c:3727
do_mount fs/namespace.c:4050 [inline]
__do_sys_mount fs/namespace.c:4238 [inline]
__se_sys_mount+0x313/0x410 fs/namespace.c:4215
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE]){+.+.}-{4:4}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
inode_lock include/linux/fs.h:979 [inline]
ocfs2_wipe_inode fs/ocfs2/inode.c:852 [inline]
ocfs2_delete_inode fs/ocfs2/inode.c:1155 [inline]
ocfs2_evict_inode+0xf86/0x4100 fs/ocfs2/inode.c:1295
evict+0x504/0x9c0 fs/inode.c:810
ocfs2_dentry_iput+0x247/0x370 fs/ocfs2/dcache.c:407
__dentry_kill+0x209/0x660 fs/dcache.c:669
dput+0x19f/0x2b0 fs/dcache.c:911
ovl_check_rename_whiteout fs/overlayfs/super.c:619 [inline]
ovl_make_workdir fs/overlayfs/super.c:714 [inline]
ovl_get_workdir+0xac3/0x17b0 fs/overlayfs/super.c:837
ovl_fill_super+0x154a/0x3da0 fs/overlayfs/super.c:1468
vfs_get_super fs/super.c:1324 [inline]
get_tree_nodev+0xb8/0x150 fs/super.c:1343
vfs_get_tree+0x8f/0x2b0 fs/super.c:1751
fc_mount fs/namespace.c:1208 [inline]
do_new_mount_fc fs/namespace.c:3651 [inline]
do_new_mount+0x302/0xa10 fs/namespace.c:3727
do_mount fs/namespace.c:4050 [inline]
__do_sys_mount fs/namespace.c:4238 [inline]
__se_sys_mount+0x313/0x410 fs/namespace.c:4215
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&osb->nfs_sync_rwlock){.+.+}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1537
ocfs2_nfs_sync_lock+0x106/0x250 fs/ocfs2/dlmglue.c:2875
ocfs2_delete_inode fs/ocfs2/inode.c:1106 [inline]
ocfs2_evict_inode+0x390/0x4100 fs/ocfs2/inode.c:1295
evict+0x504/0x9c0 fs/inode.c:810
ocfs2_dentry_iput+0x247/0x370 fs/ocfs2/dcache.c:407
__dentry_kill+0x209/0x660 fs/dcache.c:669
shrink_kill+0xa9/0x2c0 fs/dcache.c:1114
shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1141
prune_dcache_sb+0x10e/0x180 fs/dcache.c:1222
super_cache_scan+0x369/0x4b0 fs/super.c:222
do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628
shrink_one+0x28a/0x7c0 mm/vmscan.c:4955
shrink_many mm/vmscan.c:5016 [inline]
lru_gen_shrink_node mm/vmscan.c:5094 [inline]
shrink_node+0x315d/0x3780 mm/vmscan.c:6081
kswapd_shrink_node mm/vmscan.c:6941 [inline]
balance_pgdat mm/vmscan.c:7124 [inline]
kswapd+0x147c/0x2800 mm/vmscan.c:7389
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

Chain exists of:
&osb->nfs_sync_rwlock --> &ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE] --> fs_reclaim

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&ocfs2_sysfile_lock_key[INODE_ALLOC_SYSTEM_INODE]);
lock(fs_reclaim);
rlock(&osb->nfs_sync_rwlock);

*** DEADLOCK ***

2 locks held by kswapd0/77:
#0: ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7015 [inline]
#0: ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x951/0x2800 mm/vmscan.c:7389
#1: ffff88803b1de0e0 (&type->s_umount_key#51){.+.+}-{4:4}, at: super_trylock_shared fs/super.c:562 [inline]
#1: ffff88803b1de0e0 (&type->s_umount_key#51){.+.+}-{4:4}, at: super_cache_scan+0x91/0x4b0 fs/super.c:197

stack backtrace:
CPU: 0 UID: 0 PID: 77 Comm: kswapd0 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
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
down_read+0x46/0x2e0 kernel/locking/rwsem.c:1537
ocfs2_nfs_sync_lock+0x106/0x250 fs/ocfs2/dlmglue.c:2875
ocfs2_delete_inode fs/ocfs2/inode.c:1106 [inline]
ocfs2_evict_inode+0x390/0x4100 fs/ocfs2/inode.c:1295
evict+0x504/0x9c0 fs/inode.c:810
ocfs2_dentry_iput+0x247/0x370 fs/ocfs2/dcache.c:407
__dentry_kill+0x209/0x660 fs/dcache.c:669
shrink_kill+0xa9/0x2c0 fs/dcache.c:1114
shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1141
prune_dcache_sb+0x10e/0x180 fs/dcache.c:1222
super_cache_scan+0x369/0x4b0 fs/super.c:222
do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628
shrink_one+0x28a/0x7c0 mm/vmscan.c:4955
shrink_many mm/vmscan.c:5016 [inline]
lru_gen_shrink_node mm/vmscan.c:5094 [inline]
shrink_node+0x315d/0x3780 mm/vmscan.c:6081
kswapd_shrink_node mm/vmscan.c:6941 [inline]
balance_pgdat mm/vmscan.c:7124 [inline]
kswapd+0x147c/0x2800 mm/vmscan.c:7389
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>


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