メモリーの断片化が激しいときやメモリーが不足しているときにスラブオブジェクトを解放すると Red Hat Enterprise Linux がクラッシュする

Issue

• Red Hat Enterprise Linux システムが、次のいずれかに類似したバックトレースでスラブオブジェクトの割り当てまたは解放中にクラッシュします。

  [445807.422054] general protection fault: 0000 [#1] SMP NOPTI
  [445807.428420] CPU: 0 PID: 1 Comm: systemd Kdump: loaded Tainted: G           O     --------- -  - 4.18.0-305.el8.x86_64 #1
  [445807.440228] Hardware name: HPE ProLiant DL380 Gen10/ProLiant DL380 Gen10, BIOS U30 01/23/2021
  [445807.449705] RIP: 0010:kmem_cache_alloc_trace+0xdb/0x270
  [...]
  [445807.565631] Call Trace:
  [445807.568872]  allocate_cgrp_cset_links+0x72/0xb0
  [445807.574197]  find_css_set+0x296/0x6b0
  [445807.578604]  cgroup_migrate_prepare_dst+0x48/0x240
  [445807.584140]  ? wp_page_copy+0x2b7/0x4c0
  [445807.588724]  cgroup_attach_task+0x111/0x220
  [445807.593665]  ? _cond_resched+0x15/0x30
  [445807.598147]  ? rcu_sync_enter+0x53/0xd0
  [445807.602674]  __cgroup1_procs_write.constprop.16+0x100/0x140
  [445807.609001]  cgroup_file_write+0x8a/0x150
  [445807.613738]  ? __check_object_size+0xa8/0x16b
  [445807.618792]  kernfs_fop_write+0x116/0x190
  [445807.623485]  vfs_write+0xa5/0x1a0
  [445807.627465]  ksys_write+0x4f/0xb0
  [445807.631433]  do_syscall_64+0x5b/0x1a0
  [445807.635739]  entry_SYSCALL_64_after_hwframe+0x65/0xca
  
  [435280.287765] BUG: unable to handle kernel paging request at fffff305c1496248
  [435280.299353] PGD 0 P4D 0
  [435280.305424] Oops: 0000 [#1] SMP NOPTI
  [435280.314121] CPU: 90 PID: 2402112 Comm: kworker/90:0 Kdump: loaded Tainted: G           O     --------- -  - 4.18.0-305.el8.x86_64 #1
  [435280.335559] Hardware name: HPE ProLiant DL380 Gen10/ProLiant DL380 Gen10, BIOS U30 01/23/2021
  [435280.347447] Workqueue: events free_work
  [435280.354740] RIP: 0010:kfree+0x69/0x450
  [...]
  [435280.515956] Call Trace:
  [435280.526281]  free_work+0x21/0x30
  [435280.536465]  process_one_work+0x1a7/0x360
  [435280.546578]  ? create_worker+0x1a0/0x1a0
  [435280.554909]  worker_thread+0x30/0x390
  [435280.562422]  ? create_worker+0x1a0/0x1a0
  [435280.569282]  kthread+0x116/0x130
  [435280.577810]  ? kthread_flush_work_fn+0x10/0x10
  [435280.585225]  ret_from_fork+0x1f/0x40