Just triggered this on a server I was rsync'ing to.
============================================
WARNING: possible recursive locking detected
4.15.0-rc9-backup-debug+ #1 Not tainted
--------------------------------------------
sshd/24800 is trying to acquire lock:
(fs_reclaim){+.+.}, at: [<0000000084f438c2>] fs_reclaim_acquire.part.102+0x5/0x30
but task is already holding lock:
(fs_reclaim){+.+.}, at: [<0000000084f438c2>] fs_reclaim_acquire.part.102+0x5/0x30
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(fs_reclaim);
lock(fs_reclaim);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by sshd/24800:
#0: (sk_lock-AF_INET6){+.+.}, at: [<000000001a069652>] tcp_sendmsg+0x19/0x40
#1: (fs_reclaim){+.+.}, at: [<0000000084f438c2>] fs_reclaim_acquire.part.102+0x5/0x30
stack backtrace:
CPU: 3 PID: 24800 Comm: sshd Not tainted 4.15.0-rc9-backup-debug+ #1
Call Trace:
dump_stack+0xbc/0x13f
? _atomic_dec_and_lock+0x101/0x101
? fs_reclaim_acquire.part.102+0x5/0x30
? print_lock+0x54/0x68
__lock_acquire+0xa09/0x2040
? debug_show_all_locks+0x2f0/0x2f0
? mutex_destroy+0x120/0x120
? hlock_class+0xa0/0xa0
? kernel_text_address+0x5c/0x90
? __kernel_text_address+0xe/0x30
? unwind_get_return_address+0x2f/0x50
? __save_stack_trace+0x92/0x100
? graph_lock+0x8d/0x100
? check_noncircular+0x20/0x20
? __lock_acquire+0x616/0x2040
? debug_show_all_locks+0x2f0/0x2f0
? __lock_acquire+0x616/0x2040
? debug_show_all_locks+0x2f0/0x2f0
? print_irqtrace_events+0x110/0x110
? active_load_balance_cpu_stop+0x7b0/0x7b0
? debug_show_all_locks+0x2f0/0x2f0
? mark_lock+0x1b1/0xa00
? lock_acquire+0x12e/0x350
lock_acquire+0x12e/0x350
? fs_reclaim_acquire.part.102+0x5/0x30
? lockdep_rcu_suspicious+0x100/0x100
? set_next_entity+0x20e/0x10d0
? mark_lock+0x1b1/0xa00
? match_held_lock+0x8d/0x440
? mark_lock+0x1b1/0xa00
? save_trace+0x1e0/0x1e0
? print_irqtrace_events+0x110/0x110
? alloc_extent_state+0xa7/0x410
fs_reclaim_acquire.part.102+0x29/0x30
? fs_reclaim_acquire.part.102+0x5/0x30
kmem_cache_alloc+0x3d/0x2c0
? rb_erase+0xe63/0x1240
alloc_extent_state+0xa7/0x410
? lock_extent_buffer_for_io+0x3f0/0x3f0
? find_held_lock+0x6d/0xd0
? test_range_bit+0x197/0x210
? lock_acquire+0x350/0x350
? do_raw_spin_unlock+0x147/0x220
? do_raw_spin_trylock+0x100/0x100
? iotree_fs_info+0x30/0x30
__clear_extent_bit+0x3ea/0x570
? clear_state_bit+0x270/0x270
? count_range_bits+0x2f0/0x2f0
? lock_acquire+0x350/0x350
? rb_prev+0x21/0x90
try_release_extent_mapping+0x21a/0x260
__btrfs_releasepage+0xb0/0x1c0
? btrfs_submit_direct+0xca0/0xca0
? check_new_page_bad+0x1f0/0x1f0
? match_held_lock+0xa5/0x440
? debug_show_all_locks+0x2f0/0x2f0
btrfs_releasepage+0x161/0x170
? __btrfs_releasepage+0x1c0/0x1c0
? page_rmapping+0xd0/0xd0
? rmap_walk+0x100/0x100
try_to_release_page+0x162/0x1c0
? generic_file_write_iter+0x3c0/0x3c0
? page_evictable+0xcc/0x110
? lookup_address_in_pgd+0x107/0x190
shrink_page_list+0x1d5a/0x2fb0
? putback_lru_page+0x3f0/0x3f0
? save_trace+0x1e0/0x1e0
? _lookup_address_cpa.isra.13+0x40/0x60
? debug_show_all_locks+0x2f0/0x2f0
? kmem_cache_free+0x8c/0x280
? free_extent_state+0x1c8/0x3b0
? mark_lock+0x1b1/0xa00
? page_rmapping+0xd0/0xd0
? print_irqtrace_events+0x110/0x110
? shrink_node_memcg.constprop.88+0x4c9/0x5e0
? shrink_node+0x12d/0x260
? try_to_free_pages+0x418/0xaf0
? __alloc_pages_slowpath+0x976/0x1790
? __alloc_pages_nodemask+0x52c/0x5c0
? delete_node+0x28d/0x5c0
? find_held_lock+0x6d/0xd0
? free_pcppages_bulk+0x381/0x570
? lock_acquire+0x350/0x350
? do_raw_spin_unlock+0x147/0x220
? do_raw_spin_trylock+0x100/0x100
? __lock_is_held+0x51/0xc0
? _raw_spin_unlock+0x24/0x30
? free_pcppages_bulk+0x381/0x570
? mark_lock+0x1b1/0xa00
? free_compound_page+0x30/0x30
? print_irqtrace_events+0x110/0x110
? __kernel_map_pages+0x2c9/0x310
? mark_lock+0x1b1/0xa00
? print_irqtrace_events+0x110/0x110
? __delete_from_page_cache+0x2e7/0x4e0
? save_trace+0x1e0/0x1e0
? __add_to_page_cache_locked+0x680/0x680
? find_held_lock+0x6d/0xd0
? __list_add_valid+0x29/0xa0
? free_unref_page_commit+0x198/0x270
? drain_local_pages_wq+0x20/0x20
? stop_critical_timings+0x210/0x210
? mark_lock+0x1b1/0xa00
? mark_lock+0x1b1/0xa00
? print_irqtrace_events+0x110/0x110
? __lock_acquire+0x616/0x2040
? mark_lock+0x1b1/0xa00
? mark_lock+0x1b1/0xa00
? print_irqtrace_events+0x110/0x110
? __phys_addr_symbol+0x23/0x40
? __change_page_attr_set_clr+0xe86/0x1640
? __btrfs_releasepage+0x1c0/0x1c0
? mark_lock+0x1b1/0xa00
? mark_lock+0x1b1/0xa00
? print_irqtrace_events+0x110/0x110
? mark_lock+0x1b1/0xa00
? __lock_acquire+0x616/0x2040
? __lock_acquire+0x616/0x2040
? debug_show_all_locks+0x2f0/0x2f0
? swiotlb_free_coherent+0x60/0x60
? __phys_addr+0x32/0x80
? igb_xmit_frame_ring+0xad7/0x1890
? stack_access_ok+0x35/0x80
? deref_stack_reg+0xa1/0xe0
? __read_once_size_nocheck.constprop.6+0x10/0x10
? __orc_find+0x6b/0xc0
? unwind_next_frame+0x407/0xa20
? __save_stack_trace+0x5e/0x100
? stack_access_ok+0x35/0x80
? deref_stack_reg+0xa1/0xe0
? __read_once_size_nocheck.constprop.6+0x10/0x10
? __lock_acquire+0x616/0x2040
? debug_lockdep_rcu_enabled.part.37+0x16/0x30
? is_ftrace_trampoline+0x112/0x190
? ftrace_profile_pages_init+0x130/0x130
? unwind_next_frame+0x407/0xa20
? rcu_is_watching+0x88/0xd0
? unwind_get_return_address_ptr+0x50/0x50
? kernel_text_address+0x5c/0x90
? __kernel_text_address+0xe/0x30
? unwind_get_return_address+0x2f/0x50
? __save_stack_trace+0x92/0x100
? __list_add_valid+0x29/0xa0
? add_lock_to_list.isra.26+0x1d0/0x21f
? print_lockdep_cache.isra.29+0xd8/0xd8
? save_trace+0x106/0x1e0
? __isolate_lru_page+0x2dc/0x3c0
? remove_mapping+0x1b0/0x1b0
? match_held_lock+0xa5/0x440
? __lock_acquire+0x616/0x2040
? __mod_zone_page_state+0x1a/0x70
? isolate_lru_pages.isra.83+0x888/0xae0
? __isolate_lru_page+0x3c0/0x3c0
? check_usage+0x174/0x790
? mark_lock+0x1b1/0xa00
? print_irqtrace_events+0x110/0x110
? check_usage_forwards+0x2b0/0x2b0
? class_equal+0x11/0x20
? __bfs+0xed/0x430
? __phys_addr_symbol+0x23/0x40
? mutex_destroy+0x120/0x120
? match_held_lock+0x8d/0x440
? hlock_class+0xa0/0xa0
? mark_lock+0x1b1/0xa00
? save_trace+0x1e0/0x1e0
? print_irqtrace_events+0x110/0x110
? lock_acquire+0x350/0x350
? __zone_watermark_ok+0xd8/0x280
? graph_lock+0x8d/0x100
? check_noncircular+0x20/0x20
? find_held_lock+0x6d/0xd0
? shrink_inactive_list+0x3b4/0x940
? lock_acquire+0x350/0x350
? do_raw_spin_unlock+0x147/0x220
? do_raw_spin_trylock+0x100/0x100
? stop_critical_timings+0x210/0x210
? mark_held_locks+0x6e/0x90
? _raw_spin_unlock_irq+0x29/0x40
shrink_inactive_list+0x451/0x940
? save_trace+0x180/0x1e0
? putback_inactive_pages+0x9f0/0x9f0
? dev_queue_xmit_nit+0x548/0x660
? __kernel_map_pages+0x2c9/0x310
? set_pages_rw+0xe0/0xe0
? get_page_from_freelist+0x1ea5/0x2ca0
? match_held_lock+0x8d/0x440
? blk_start_plug+0x17d/0x1e0
? kblockd_schedule_delayed_work_on+0x20/0x20
? print_irqtrace_events+0x110/0x110
? cpumask_next+0x1d/0x20
? zone_reclaimable_pages+0x25b/0x470
? mark_held_locks+0x6e/0x90
? __remove_mapping+0x4e0/0x4e0
shrink_node_memcg.constprop.88+0x4c9/0x5e0
? __delayacct_freepages_start+0x28/0x40
? lock_acquire+0x311/0x350
? shrink_active_list+0x9c0/0x9c0
? stop_critical_timings+0x210/0x210
? allow_direct_reclaim.part.82+0xea/0x220
? mark_held_locks+0x6e/0x90
? ktime_get+0x1f0/0x3e0
? shrink_node+0x12d/0x260
shrink_node+0x12d/0x260
? shrink_node_memcg.constprop.88+0x5e0/0x5e0
? __lock_is_held+0x51/0xc0
try_to_free_pages+0x418/0xaf0
? shrink_node+0x260/0x260
? lock_acquire+0x12e/0x350
? lock_acquire+0x12e/0x350
? fs_reclaim_acquire.part.102+0x5/0x30
? lockdep_rcu_suspicious+0x100/0x100
? rcu_note_context_switch+0x520/0x520
? wake_all_kswapds+0x10a/0x150
__alloc_pages_slowpath+0x976/0x1790
? __zone_watermark_ok+0x280/0x280
? warn_alloc+0x250/0x250
? __lock_acquire+0x616/0x2040
? match_held_lock+0x8d/0x440
? save_trace+0x1e0/0x1e0
? debug_show_all_locks+0x2f0/0x2f0
? match_held_lock+0xa5/0x440
? stack_access_ok+0x35/0x80
? save_trace+0x1e0/0x1e0
? __read_once_size_nocheck.constprop.6+0x10/0x10
? __lock_acquire+0x616/0x2040
? match_held_lock+0xa5/0x440
? find_held_lock+0x6d/0xd0
? __lock_is_held+0x51/0xc0
? rcu_note_context_switch+0x520/0x520
? perf_trace_sched_switch+0x560/0x560
? __might_sleep+0x58/0xe0
__alloc_pages_nodemask+0x52c/0x5c0
? gfp_pfmemalloc_allowed+0xc0/0xc0
? kernel_text_address+0x5c/0x90
? __kernel_text_address+0xe/0x30
? unwind_get_return_address+0x2f/0x50
? memcmp+0x45/0x70
? match_held_lock+0x8d/0x440
? depot_save_stack+0x12e/0x480
? match_held_lock+0xa5/0x440
? stop_critical_timings+0x210/0x210
? sk_stream_alloc_skb+0xb8/0x340
? mark_held_locks+0x6e/0x90
? new_slab+0x2f3/0x3f0
new_slab+0x374/0x3f0
___slab_alloc.constprop.81+0x47e/0x5a0
? __alloc_skb+0xee/0x390
? __alloc_skb+0xee/0x390
? __alloc_skb+0xee/0x390
? __slab_alloc.constprop.80+0x32/0x60
__slab_alloc.constprop.80+0x32/0x60
? __alloc_skb+0xee/0x390
__kmalloc_track_caller+0x267/0x310
__kmalloc_reserve.isra.40+0x29/0x80
__alloc_skb+0xee/0x390
? __skb_splice_bits+0x3e0/0x3e0
? ip6_mtu+0x1d9/0x290
? ip6_link_failure+0x3c0/0x3c0
? tcp_current_mss+0x1d8/0x2f0
? tcp_sync_mss+0x520/0x520
sk_stream_alloc_skb+0xb8/0x340
? tcp_ioctl+0x280/0x280
tcp_sendmsg_locked+0x8e6/0x1d30
? match_held_lock+0x8d/0x440
? mark_lock+0x1b1/0xa00
? tcp_set_state+0x450/0x450
? debug_show_all_locks+0x2f0/0x2f0
? match_held_lock+0x8d/0x440
? save_trace+0x1e0/0x1e0
? find_held_lock+0x6d/0xd0
? lock_acquire+0x12e/0x350
? lock_acquire+0x12e/0x350
? tcp_sendmsg+0x19/0x40
? lockdep_rcu_suspicious+0x100/0x100
? do_raw_spin_trylock+0x100/0x100
? stop_critical_timings+0x210/0x210
? mark_held_locks+0x6e/0x90
? __local_bh_enable_ip+0x94/0x100
? lock_sock_nested+0x51/0xb0
tcp_sendmsg+0x27/0x40
inet_sendmsg+0xd0/0x310
? inet_recvmsg+0x360/0x360
? match_held_lock+0x8d/0x440
? inet_recvmsg+0x360/0x360
sock_write_iter+0x17a/0x240
? sock_ioctl+0x290/0x290
? find_held_lock+0x6d/0xd0
__vfs_write+0x2ab/0x380
? kernel_read+0xa0/0xa0
? __context_tracking_exit.part.4+0xe7/0x290
? lock_acquire+0x350/0x350
? __fdget_pos+0x7f/0x110
? __fdget_raw+0x10/0x10
vfs_write+0xfb/0x260
SyS_write+0xb6/0x140
? SyS_read+0x140/0x140
? SyS_clock_settime+0x120/0x120
? mark_held_locks+0x1c/0x90
? do_syscall_64+0x110/0xc05
? SyS_read+0x140/0x140
do_syscall_64+0x1e5/0xc05
? syscall_return_slowpath+0x5b0/0x5b0
? lock_acquire+0x350/0x350
? lockdep_rcu_suspicious+0x100/0x100
? get_vtime_delta+0x15/0xf0
? get_vtime_delta+0x8b/0xf0
? vtime_user_enter+0x7f/0x90
? __context_tracking_enter+0x13c/0x2b0
? __context_tracking_enter+0x13c/0x2b0
? context_tracking_exit.part.5+0x40/0x40
? rcu_is_watching+0x88/0xd0
? time_hardirqs_on+0x220/0x220
? prepare_exit_to_usermode+0x1d0/0x2a0
? enter_from_user_mode+0x30/0x30
? entry_SYSCALL_64_after_hwframe+0x18/0x2e
? trace_hardirqs_off_caller+0xc2/0x110
? trace_hardirqs_off_thunk+0x1a/0x1c
entry_SYSCALL64_slow_path+0x25/0x25
RIP: 0033:0x7f26d47d1974
RSP: 002b:00007ffd62e2f548 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000024 RCX: 00007f26d47d1974
RDX: 0000000000000024 RSI: 000055a0bc9a6220 RDI: 0000000000000003
RBP: 000055a0bc984370 R08: 0000000000000000 R09: 00007ffd62fb9080
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000
R13: 000055a0bc311ab0 R14: 0000000000000003 R15: 00007ffd62e2f5cf
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