syzbot

======================================================
WARNING: possible circular locking dependency detected
6.8.0-syzkaller-11405-g906a93befec8 #0 Not tainted
------------------------------------------------------
kswapd0/109 is trying to acquire lock:
ffff888022fc0958 (&qinf->qi_tree_lock){+.+.}-{3:3}, at: xfs_qm_dqfree_one+0x6f/0x1a0 fs/xfs/xfs_qm.c:1654

but task is already holding lock:
ffffffff8d930be0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x19a0 mm/vmscan.c:6782

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:3698 [inline]
       fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3712
       might_alloc include/linux/sched/mm.h:312 [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_scall_setqlim+0x172/0x1980 fs/xfs/xfs_qm_syscalls.c:300
       xfs_fs_set_dqblk+0x166/0x1e0 fs/xfs/xfs_quotaops.c:267
       quota_setquota+0x4c5/0x5f0 fs/quota/quota.c:310
       do_quotactl+0xb03/0x13e0 fs/quota/quota.c:802
       __do_sys_quotactl fs/quota/quota.c:961 [inline]
       __se_sys_quotactl fs/quota/quota.c:917 [inline]
       __x64_sys_quotactl+0x1b4/0x440 fs/quota/quota.c:917
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x6d/0x75

-> #0 (&qinf->qi_tree_lock){+.+.}-{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
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
       xfs_qm_dqfree_one+0x6f/0x1a0 fs/xfs/xfs_qm.c:1654
       xfs_qm_shrink_scan+0x25c/0x3f0 fs/xfs/xfs_qm.c:531
       do_shrink_slab+0x44f/0x1160 mm/shrinker.c:435
       shrink_slab+0x18a/0x1310 mm/shrinker.c:662
       shrink_one+0x493/0x7c0 mm/vmscan.c:4774
       shrink_many mm/vmscan.c:4835 [inline]
       lru_gen_shrink_node mm/vmscan.c:4935 [inline]
       shrink_node+0x231f/0x3a80 mm/vmscan.c:5894
       kswapd_shrink_node mm/vmscan.c:6704 [inline]
       balance_pgdat+0x9a0/0x19a0 mm/vmscan.c:6895
       kswapd+0x5ea/0xb90 mm/vmscan.c:7164
       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:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

1 lock held by kswapd0/109:
 #0: ffffffff8d930be0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x19a0 mm/vmscan.c:6782

stack backtrace:
CPU: 3 PID: 109 Comm: kswapd0 Not tainted 6.8.0-syzkaller-11405-g906a93befec8 #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
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
 xfs_qm_dqfree_one+0x6f/0x1a0 fs/xfs/xfs_qm.c:1654
 xfs_qm_shrink_scan+0x25c/0x3f0 fs/xfs/xfs_qm.c:531
 do_shrink_slab+0x44f/0x1160 mm/shrinker.c:435
 shrink_slab+0x18a/0x1310 mm/shrinker.c:662
 shrink_one+0x493/0x7c0 mm/vmscan.c:4774
 shrink_many mm/vmscan.c:4835 [inline]
 lru_gen_shrink_node mm/vmscan.c:4935 [inline]
 shrink_node+0x231f/0x3a80 mm/vmscan.c:5894
 kswapd_shrink_node mm/vmscan.c:6704 [inline]
 balance_pgdat+0x9a0/0x19a0 mm/vmscan.c:6895
 kswapd+0x5ea/0xb90 mm/vmscan.c:7164
 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>