syzbot

======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc4-syzkaller-00148-g50736169ecc8 #0 Not tainted
------------------------------------------------------
kswapd0/111 is trying to acquire lock:
ffff88801f71e610 (sb_internal#2){.+.+}-{0:0}, at: btrfs_commit_inode_delayed_inode+0x110/0x330 fs/btrfs/delayed-inode.c:1275

but task is already holding lock:
ffffffff8dd3ab20 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1970 mm/vmscan.c:6798

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:3801 [inline]
       fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3815
       might_alloc include/linux/sched/mm.h:334 [inline]
       slab_pre_alloc_hook mm/slub.c:3891 [inline]
       slab_alloc_node mm/slub.c:3981 [inline]
       kmalloc_trace_noprof+0x51/0x310 mm/slub.c:4148
       kmalloc_noprof include/linux/slab.h:660 [inline]
       ulist_alloc+0x77/0x1c0 fs/btrfs/ulist.c:98
       btrfs_quota_enable+0x342/0x1ef0 fs/btrfs/qgroup.c:1051
       btrfs_ioctl_quota_ctl fs/btrfs/ioctl.c:3765 [inline]
       btrfs_ioctl+0x6af4/0x8290 fs/btrfs/ioctl.c:4762
       __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
       btrfs_quota_enable+0x3a1/0x1ef0 fs/btrfs/qgroup.c:1086
       btrfs_ioctl_quota_ctl fs/btrfs/ioctl.c:3765 [inline]
       btrfs_ioctl+0x6af4/0x8290 fs/btrfs/ioctl.c:4762
       __do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1007
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #2 (btrfs_trans_num_extwriters){++++}-{0:0}:
       join_transaction+0x164/0xf40 fs/btrfs/transaction.c:315
       start_transaction+0x427/0x1a70 fs/btrfs/transaction.c:700
       btrfs_rebuild_free_space_tree+0xaa/0x480 fs/btrfs/free-space-tree.c:1323
       btrfs_start_pre_rw_mount+0x218/0xf60 fs/btrfs/disk-io.c:2999
       open_ctree+0x41ab/0x52e0 fs/btrfs/disk-io.c:3554
       btrfs_fill_super fs/btrfs/super.c:946 [inline]
       btrfs_get_tree_super fs/btrfs/super.c:1863 [inline]
       btrfs_get_tree+0x11e9/0x1b90 fs/btrfs/super.c:2089
       vfs_get_tree+0x8f/0x380 fs/super.c:1780
       fc_mount+0x16/0xc0 fs/namespace.c:1125
       btrfs_get_tree_subvol fs/btrfs/super.c:2052 [inline]
       btrfs_get_tree+0xa53/0x1b90 fs/btrfs/super.c:2090
       vfs_get_tree+0x8f/0x380 fs/super.c:1780
       do_new_mount fs/namespace.c:3352 [inline]
       path_mount+0x6e1/0x1f10 fs/namespace.c:3679
       do_mount fs/namespace.c:3692 [inline]
       __do_sys_mount fs/namespace.c:3898 [inline]
       __se_sys_mount fs/namespace.c:3875 [inline]
       __ia32_sys_mount+0x295/0x320 fs/namespace.c:3875
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #1 (btrfs_trans_num_writers){++++}-{0:0}:
       join_transaction+0x148/0xf40 fs/btrfs/transaction.c:314
       start_transaction+0x427/0x1a70 fs/btrfs/transaction.c:700
       btrfs_rebuild_free_space_tree+0xaa/0x480 fs/btrfs/free-space-tree.c:1323
       btrfs_start_pre_rw_mount+0x218/0xf60 fs/btrfs/disk-io.c:2999
       open_ctree+0x41ab/0x52e0 fs/btrfs/disk-io.c:3554
       btrfs_fill_super fs/btrfs/super.c:946 [inline]
       btrfs_get_tree_super fs/btrfs/super.c:1863 [inline]
       btrfs_get_tree+0x11e9/0x1b90 fs/btrfs/super.c:2089
       vfs_get_tree+0x8f/0x380 fs/super.c:1780
       fc_mount+0x16/0xc0 fs/namespace.c:1125
       btrfs_get_tree_subvol fs/btrfs/super.c:2052 [inline]
       btrfs_get_tree+0xa53/0x1b90 fs/btrfs/super.c:2090
       vfs_get_tree+0x8f/0x380 fs/super.c:1780
       do_new_mount fs/namespace.c:3352 [inline]
       path_mount+0x6e1/0x1f10 fs/namespace.c:3679
       do_mount fs/namespace.c:3692 [inline]
       __do_sys_mount fs/namespace.c:3898 [inline]
       __se_sys_mount fs/namespace.c:3875 [inline]
       __ia32_sys_mount+0x295/0x320 fs/namespace.c:3875
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
       entry_SYSENTER_compat_after_hwframe+0x84/0x8e

-> #0 (sb_internal#2){.+.+}-{0:0}:
       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+0x1b1/0x560 kernel/locking/lockdep.c:5719
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1655 [inline]
       sb_start_intwrite include/linux/fs.h:1838 [inline]
       start_transaction+0xbc1/0x1a70 fs/btrfs/transaction.c:694
       btrfs_commit_inode_delayed_inode+0x110/0x330 fs/btrfs/delayed-inode.c:1275
       btrfs_evict_inode+0x960/0xe80 fs/btrfs/inode.c:5291
       evict+0x2ed/0x6c0 fs/inode.c:667
       iput_final fs/inode.c:1741 [inline]
       iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
       iput+0x5c/0x80 fs/inode.c:1757
       dentry_unlink_inode+0x295/0x480 fs/dcache.c:400
       __dentry_kill+0x1d0/0x600 fs/dcache.c:603
       dput.part.0+0x4b1/0x9b0 fs/dcache.c:845
       dput+0x1f/0x30 fs/dcache.c:835
       ovl_stack_put+0x60/0x90 fs/overlayfs/util.c:132
       ovl_destroy_inode+0xc6/0x190 fs/overlayfs/super.c:182
       destroy_inode+0xc4/0x1b0 fs/inode.c:311
       iput_final fs/inode.c:1741 [inline]
       iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
       iput+0x5c/0x80 fs/inode.c:1757
       dentry_unlink_inode+0x295/0x480 fs/dcache.c:400
       __dentry_kill+0x1d0/0x600 fs/dcache.c:603
       shrink_kill fs/dcache.c:1048 [inline]
       shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075
       prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156
       super_cache_scan+0x32a/0x550 fs/super.c:221
       do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
       shrink_slab_memcg mm/shrinker.c:548 [inline]
       shrink_slab+0xa87/0x1310 mm/shrinker.c:626
       shrink_one+0x493/0x7c0 mm/vmscan.c:4790
       shrink_many mm/vmscan.c:4851 [inline]
       lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4951
       shrink_node mm/vmscan.c:5910 [inline]
       kswapd_shrink_node mm/vmscan.c:6720 [inline]
       balance_pgdat+0x1105/0x1970 mm/vmscan.c:6911
       kswapd+0x5ea/0xbf0 mm/vmscan.c:7180
       kthread+0x2c1/0x3a0 kernel/kthread.c:389
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

other info that might help us debug this:

Chain exists of:
  sb_internal#2 --> &fs_info->qgroup_ioctl_lock --> fs_reclaim

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(&fs_info->qgroup_ioctl_lock);
                               lock(fs_reclaim);
  rlock(sb_internal#2);

 *** DEADLOCK ***

2 locks held by kswapd0/111:
 #0: ffffffff8dd3ab20 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1970 mm/vmscan.c:6798
 #1: ffff888000a4a0e0 (&type->s_umount_key#57){++++}-{3:3}, at: super_trylock_shared fs/super.c:562 [inline]
 #1: ffff888000a4a0e0 (&type->s_umount_key#57){++++}-{3:3}, at: super_cache_scan+0x96/0x550 fs/super.c:196

stack backtrace:
CPU: 3 PID: 111 Comm: kswapd0 Not tainted 6.10.0-rc4-syzkaller-00148-g50736169ecc8 #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+0x1b1/0x560 kernel/locking/lockdep.c:5719
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 __sb_start_write include/linux/fs.h:1655 [inline]
 sb_start_intwrite include/linux/fs.h:1838 [inline]
 start_transaction+0xbc1/0x1a70 fs/btrfs/transaction.c:694
 btrfs_commit_inode_delayed_inode+0x110/0x330 fs/btrfs/delayed-inode.c:1275
 btrfs_evict_inode+0x960/0xe80 fs/btrfs/inode.c:5291
 evict+0x2ed/0x6c0 fs/inode.c:667
 iput_final fs/inode.c:1741 [inline]
 iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
 iput+0x5c/0x80 fs/inode.c:1757
 dentry_unlink_inode+0x295/0x480 fs/dcache.c:400
 __dentry_kill+0x1d0/0x600 fs/dcache.c:603
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:845
 dput+0x1f/0x30 fs/dcache.c:835
 ovl_stack_put+0x60/0x90 fs/overlayfs/util.c:132
 ovl_destroy_inode+0xc6/0x190 fs/overlayfs/super.c:182
 destroy_inode+0xc4/0x1b0 fs/inode.c:311
 iput_final fs/inode.c:1741 [inline]
 iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
 iput+0x5c/0x80 fs/inode.c:1757
 dentry_unlink_inode+0x295/0x480 fs/dcache.c:400
 __dentry_kill+0x1d0/0x600 fs/dcache.c:603
 shrink_kill fs/dcache.c:1048 [inline]
 shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075
 prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156
 super_cache_scan+0x32a/0x550 fs/super.c:221
 do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
 shrink_slab_memcg mm/shrinker.c:548 [inline]
 shrink_slab+0xa87/0x1310 mm/shrinker.c:626
 shrink_one+0x493/0x7c0 mm/vmscan.c:4790
 shrink_many mm/vmscan.c:4851 [inline]
 lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4951
 shrink_node mm/vmscan.c:5910 [inline]
 kswapd_shrink_node mm/vmscan.c:6720 [inline]
 balance_pgdat+0x1105/0x1970 mm/vmscan.c:6911
 kswapd+0x5ea/0xbf0 mm/vmscan.c:7180
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>