Huge number of negative dentries cause massive calls to shrink_slab() --> prune_super() --> prune_dcache_sb() --> __prune_dcache_sb() and soft lockups, rcu_sched CPU stalls, and a hard lockup.

Issue

• Huge number of negative dentries cause massive calls to shrink_slab() --> prune_super() --> prune_dcache_sb() --> __prune_dcache_sb() and soft lockups, rcu_sched CPU stalls, and a hard lockup.

[1259814.007885] Kernel panic - not syncing: Hard LOCKUP
[1259814.007887] CPU: 8 PID: 119447 Comm: statsd_exporter Kdump: loaded Tainted: G           OEL ------------ T 3.10.0-1160.99.1.el7.x86_64 #1
[1259814.007888] Hardware name: HPE ProLiant DL325 Gen10 Plus/ProLiant DL325 Gen10 Plus, BIOS A43 12/03/2021
[1259814.007888] Call Trace:
[1259814.007891]  <NMI>  [<ffffffff9b1b1bec>] dump_stack+0x19/0x1f
[1259814.007893]  [<ffffffff9b1ab708>] panic+0xe8/0x21f
[1259814.007897]  [<ffffffff9aa30a78>] ? show_regs+0x58/0x290
[1259814.007900]  [<ffffffff9aa9f523>] nmi_panic+0x43/0x50
[1259814.007903]  [<ffffffff9ab57479>] watchdog_overflow_callback+0x119/0x140
[1259814.007907]  [<ffffffff9abb3317>] __perf_event_overflow+0x57/0x100
[1259814.007910]  [<ffffffff9abbcdd4>] perf_event_overflow+0x14/0x20
[1259814.007915]  [<ffffffff9aa05655>] x86_pmu_handle_irq+0x125/0x180
[1259814.007919]  [<ffffffff9aa06825>] amd_pmu_handle_irq+0x35/0x80
[1259814.007921]  [<ffffffff9b1bb039>] perf_event_nmi_handler+0x39/0x60
[1259814.007923]  [<ffffffff9b1bc9cc>] nmi_handle.isra.0+0x8c/0x150
[1259814.007925]  [<ffffffff9b1bcbed>] do_nmi+0x15d/0x460
[1259814.007928]  [<ffffffff9b1bbdf4>] end_repeat_nmi+0x1e/0x81
[1259814.007930]  [<ffffffff9ab1ec76>] ? native_queued_spin_lock_slowpath+0x156/0x200
[1259814.007932]  [<ffffffff9ab1ec76>] ? native_queued_spin_lock_slowpath+0x156/0x200
[1259814.007934]  [<ffffffff9ab1ec76>] ? native_queued_spin_lock_slowpath+0x156/0x200
[1259814.007936]  <EOE>  <IRQ>  [<ffffffff9b1ac21a>] queued_spin_lock_slowpath+0xb/0x13
[1259814.007938]  [<ffffffff9b1ba7bb>] _raw_spin_lock_irqsave+0x3b/0x40
[1259814.007940]  [<ffffffff9ab646e9>] rcu_check_callbacks+0x549/0x730
[1259814.007942]  [<ffffffff9ab17630>] ? tick_sched_do_timer+0x60/0x60
[1259814.007944]  [<ffffffff9aab3fb6>] update_process_times+0x46/0x80
[1259814.007946]  [<ffffffff9ab17360>] tick_sched_handle+0x30/0x80
[1259814.007948]  [<ffffffff9ab17669>] tick_sched_timer+0x39/0x80
[1259814.007950]  [<ffffffff9aacfb1e>] __hrtimer_run_queues+0x10e/0x270
[1259814.007952]  [<ffffffff9aad00af>] hrtimer_interrupt+0xaf/0x1e0
[1259814.007954]  [<ffffffff9aa5fbcb>] local_apic_timer_interrupt+0x3b/0x70
[1259814.007956]  [<ffffffff9b1ca053>] smp_apic_timer_interrupt+0x43/0x60
[1259814.007958]  [<ffffffff9b1c63f2>] apic_timer_interrupt+0x172/0x180
[1259814.007960]  <EOI>  [<ffffffff9ada2dd6>] ? radix_tree_next_chunk+0x116/0x2d0
[1259814.007962]  [<ffffffff9ab1ec42>] ? native_queued_spin_lock_slowpath+0x122/0x200
[1259814.007964]  [<ffffffff9b1ac21a>] queued_spin_lock_slowpath+0xb/0x13
[1259814.007966]  [<ffffffff9b1ba734>] _raw_spin_lock+0x24/0x30
[1259814.007968]  [<ffffffff9ac75a19>] __prune_dcache_sb+0x69/0x210
[1259814.007970]  [<ffffffff9ac77f73>] prune_dcache_sb+0x13/0x20
[1259814.007972]  [<ffffffff9ac5e910>] prune_super+0x120/0x1a0
[1259814.007974]  [<ffffffff9abdd745>] shrink_slab+0x175/0x360
[1259814.007976]  [<ffffffff9ac50661>] ? vmpressure+0x21/0x90
[1259814.007978]  [<ffffffff9abe0a5a>] do_try_to_free_pages+0x3ca/0x520
[1259814.007980]  [<ffffffff9abe0cac>] try_to_free_pages+0xfc/0x180
[1259814.007982]  [<ffffffff9abd4611>] __alloc_pages_nodemask+0x841/0xbf0
[1259814.007985]  [<ffffffff9ace1ee0>] ? stat_open+0x50/0x50
[1259814.007987]  [<ffffffff9b1adf42>] kmalloc_large_node+0x5f/0x84
[1259814.007988]  [<ffffffff9ac35add>] __kmalloc_node+0x24d/0x2b0
[1259814.007990]  [<ffffffff9ace1ee0>] ? stat_open+0x50/0x50
[1259814.007992]  [<ffffffff9abe9f89>] kvmalloc_node+0x49/0xe0
[1259814.007994]  [<ffffffff9ac84ba1>] single_open_size+0x41/0xc0
[1259814.007996]  [<ffffffff9ac84760>] ? single_open+0xc0/0xc0
[1259814.007998]  [<ffffffff9ace1ed5>] stat_open+0x45/0x50
[1259814.007999]  [<ffffffff9acd7e22>] proc_reg_open+0x72/0x110
[1259814.008001]  [<ffffffff9ac59422>] do_dentry_open+0x1e2/0x2d0
[1259814.008003]  [<ffffffff9ad1aef2>] ? security_inode_permission+0x22/0x30
[1259814.008005]  [<ffffffff9acd7db0>] ? proc_reg_release+0x80/0x80
[1259814.008007]  [<ffffffff9ac595aa>] vfs_open+0x5a/0xb0
[1259814.008009]  [<ffffffff9ac67dea>] ? may_open+0x5a/0x130
[1259814.008010]  [<ffffffff9ac6c8c6>] do_last+0x1f6/0x1380
[1259814.008012]  [<ffffffff9aa9c024>] ? mmput+0x14/0x100
[1259814.008014]  [<ffffffff9ac35f06>] ? kmem_cache_alloc_trace+0x1d6/0x200
[1259814.008016]  [<ffffffff9ac6db1d>] path_openat+0xcd/0x5a0
[1259814.008019]  [<ffffffff9b09bc50>] ? sk_run_filter+0x550/0x760
[1259814.008020]  [<ffffffff9ac6f4dd>] do_filp_open+0x4d/0xc0
[1259814.008022]  [<ffffffff9ac7dd47>] ? __alloc_fd+0x47/0x180
[1259814.008024]  [<ffffffff9ac5aba4>] do_sys_open+0x124/0x220
[1259814.008026]  [<ffffffff9ac5ace4>] SyS_openat+0x14/0x20
[1259814.008028]  [<ffffffff9b1c562e>] tracesys+0xa6/0xcc