[syzbot] [xfs?] possible deadlock in xfs_ilock

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e5e038b7ae9d Merge tag 'fs_for_v6.9-rc1' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1276d246180000
kernel config: https://syzkaller.appspot.com/x/.config?x=6ce8d253b68e67fe
dashboard link: https://syzkaller.appspot.com/bug?extid=d247769793ec169e4bf9
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-e5e038b7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/82ab7eda09bc/vmlinux-e5e038b7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bda17336e65d/bzImage-e5e038b7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d24776...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.8.0-syzkaller-06619-ge5e038b7ae9d #0 Not tainted
------------------------------------------------------
kswapd1/112 is trying to acquire lock:
ffff88804a8f6d98 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock+0x2ef/0x3e0 fs/xfs/xfs_inode.c:206

but task is already holding lock:
ffffffff8d92fb40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x15f/0x1a90 mm/vmscan.c:6774

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (fs_reclaim){+.+.}-{0:0}:
__fs_reclaim_acquire mm/page_alloc.c:3692 [inline]
fs_reclaim_acquire+0x102/0x150 mm/page_alloc.c:3706
might_alloc include/linux/sched/mm.h:303 [inline]
slab_pre_alloc_hook mm/slub.c:3746 [inline]
slab_alloc_node mm/slub.c:3827 [inline]
kmem_cache_alloc+0x4f/0x320 mm/slub.c:3852
radix_tree_node_alloc.constprop.0+0x7c/0x350 lib/radix-tree.c:276
radix_tree_extend+0x1a2/0x4d0 lib/radix-tree.c:425
__radix_tree_create lib/radix-tree.c:613 [inline]
radix_tree_insert+0x499/0x630 lib/radix-tree.c:712
xfs_qm_dqget_cache_insert.constprop.0+0x38/0x2c0 fs/xfs/xfs_dquot.c:826
xfs_qm_dqget+0x182/0x4a0 fs/xfs/xfs_dquot.c:901
xfs_qm_vop_dqalloc+0x49a/0xe10 fs/xfs/xfs_qm.c:1755
xfs_setattr_nonsize+0x8ca/0xca0 fs/xfs/xfs_iops.c:707
xfs_vn_setattr+0x209/0x260 fs/xfs/xfs_iops.c:1027
notify_change+0x742/0x11c0 fs/attr.c:497
chown_common+0x598/0x660 fs/open.c:790
do_fchownat+0x1af/0x210 fs/open.c:821
ksys_lchown include/linux/syscalls.h:1243 [inline]
__do_sys_lchown16 kernel/uid16.c:30 [inline]
__se_sys_lchown16 kernel/uid16.c:28 [inline]
__ia32_sys_lchown16+0xe6/0x120 kernel/uid16.c:28
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x7a/0x120 arch/x86/entry/common.c:321
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346
entry_SYSENTER_compat_after_hwframe+0x7a/0x84

-> #1 (&qinf->qi_tree_lock){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
xfs_qm_dqget_cache_lookup+0x66/0x820 fs/xfs/xfs_dquot.c:784
xfs_qm_dqget_inode+0x1e7/0x6d0 fs/xfs/xfs_dquot.c:986
xfs_qm_dqattach_one+0x26f/0x530 fs/xfs/xfs_qm.c:278
xfs_qm_dqattach_locked+0x1c6/0x2d0 fs/xfs/xfs_qm.c:337
xfs_qm_vop_dqalloc+0x344/0xe10 fs/xfs/xfs_qm.c:1710
xfs_setattr_nonsize+0x8ca/0xca0 fs/xfs/xfs_iops.c:707
xfs_vn_setattr+0x209/0x260 fs/xfs/xfs_iops.c:1027
notify_change+0x742/0x11c0 fs/attr.c:497
chown_common+0x598/0x660 fs/open.c:790
do_fchownat+0x1af/0x210 fs/open.c:821
ksys_lchown include/linux/syscalls.h:1243 [inline]
__do_sys_lchown16 kernel/uid16.c:30 [inline]
__se_sys_lchown16 kernel/uid16.c:28 [inline]
__ia32_sys_lchown16+0xe6/0x120 kernel/uid16.c:28
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x7a/0x120 arch/x86/entry/common.c:321
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346
entry_SYSENTER_compat_after_hwframe+0x7a/0x84

-> #0 (&xfs_dir_ilock_class){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1b1/0x540 kernel/locking/lockdep.c:5719
down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1695
xfs_ilock+0x2ef/0x3e0 fs/xfs/xfs_inode.c:206
xfs_reclaim_inode fs/xfs/xfs_icache.c:945 [inline]
xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1631 [inline]
xfs_icwalk_ag+0xca6/0x1740 fs/xfs/xfs_icache.c:1713
xfs_icwalk+0x57/0x100 fs/xfs/xfs_icache.c:1762
xfs_reclaim_inodes_nr+0x182/0x250 fs/xfs/xfs_icache.c:1011
super_cache_scan+0x409/0x550 fs/super.c:227
do_shrink_slab+0x44f/0x1160 mm/shrinker.c:435
shrink_slab+0x18a/0x1310 mm/shrinker.c:662
shrink_one+0x493/0x7b0 mm/vmscan.c:4767
shrink_many mm/vmscan.c:4828 [inline]
lru_gen_shrink_node mm/vmscan.c:4929 [inline]
shrink_node+0x2191/0x3770 mm/vmscan.c:5888
kswapd_shrink_node mm/vmscan.c:6696 [inline]
balance_pgdat+0x9d0/0x1a90 mm/vmscan.c:6886
kswapd+0x5c1/0xc10 mm/vmscan.c:7146
kthread+0x2c1/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

other info that might help us debug this:

Chain exists of:
&xfs_dir_ilock_class --> &qinf->qi_tree_lock --> fs_reclaim

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&qinf->qi_tree_lock);
lock(fs_reclaim);
lock(&xfs_dir_ilock_class);

*** DEADLOCK ***

2 locks held by kswapd1/112:
#0: ffffffff8d92fb40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x15f/0x1a90 mm/vmscan.c:6774
#1: ffff8880680100e0 (&type->s_umount_key#81){++++}-{3:3}, at: super_trylock_shared fs/super.c:561 [inline]
#1: ffff8880680100e0 (&type->s_umount_key#81){++++}-{3:3}, at: super_cache_scan+0x96/0x550 fs/super.c:196

stack backtrace:
CPU: 2 PID: 112 Comm: kswapd1 Not tainted 6.8.0-syzkaller-06619-ge5e038b7ae9d #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1b1/0x540 kernel/locking/lockdep.c:5719
down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1695
xfs_ilock+0x2ef/0x3e0 fs/xfs/xfs_inode.c:206
xfs_reclaim_inode fs/xfs/xfs_icache.c:945 [inline]
xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1631 [inline]
xfs_icwalk_ag+0xca6/0x1740 fs/xfs/xfs_icache.c:1713
xfs_icwalk+0x57/0x100 fs/xfs/xfs_icache.c:1762
xfs_reclaim_inodes_nr+0x182/0x250 fs/xfs/xfs_icache.c:1011
super_cache_scan+0x409/0x550 fs/super.c:227
do_shrink_slab+0x44f/0x1160 mm/shrinker.c:435
shrink_slab+0x18a/0x1310 mm/shrinker.c:662
shrink_one+0x493/0x7b0 mm/vmscan.c:4767
shrink_many mm/vmscan.c:4828 [inline]
lru_gen_shrink_node mm/vmscan.c:4929 [inline]
shrink_node+0x2191/0x3770 mm/vmscan.c:5888
kswapd_shrink_node mm/vmscan.c:6696 [inline]
balance_pgdat+0x9d0/0x1a90 mm/vmscan.c:6886
kswapd+0x5c1/0xc10 mm/vmscan.c:7146
kthread+0x2c1/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
</TASK>


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