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BUG: KCSAN: data-race in yama_task_free / yama_task_free

write to 0xffff88812182cf50 of 1 bytes by interrupt on cpu 0:
 yama_ptracer_del security/yama/yama_lsm.c:191 [inline]
 yama_task_free+0xc6/0x150 security/yama/yama_lsm.c:207
 security_task_free+0x3f/0xa0 security/security.c:1580
 __put_task_struct+0x96/0x370 kernel/fork.c:750
 put_task_struct include/linux/sched/task.h:126 [inline]
 delayed_put_task_struct+0x52/0x160 kernel/exit.c:172
 rcu_do_batch kernel/rcu/tree.c:2396 [inline]
 rcu_core+0x606/0xb60 kernel/rcu/tree.c:2623
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2632
 __do_softirq+0x198/0x360 kernel/softirq.c:292
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 do_softirq_own_stack+0x5d/0x80 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:387 [inline]
 __irq_exit_rcu+0x115/0x120 kernel/softirq.c:417
 sysvec_apic_timer_interrupt+0xd9/0xf0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596
 refcount_add include/linux/refcount.h:206 [inline]
 refcount_inc include/linux/refcount.h:241 [inline]
 get_ctx kernel/events/core.c:1237 [inline]
 perf_event_init_context kernel/events/core.c:12660 [inline]
 perf_event_init_task+0x47a/0x4c0 kernel/events/core.c:12685
 copy_process+0xff6/0x32b0 kernel/fork.c:2072
 _do_fork+0xf1/0x660 kernel/fork.c:2443
 kernel_thread+0x85/0xb0 kernel/fork.c:2531
 create_kthread kernel/kthread.c:314 [inline]
 kthreadd+0x317/0x3d0 kernel/kthread.c:632
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

read to 0xffff88812182cf50 of 1 bytes by interrupt on cpu 1:
 yama_ptracer_del security/yama/yama_lsm.c:187 [inline]
 yama_task_free+0x61/0x150 security/yama/yama_lsm.c:207
 security_task_free+0x3f/0xa0 security/security.c:1580
 __put_task_struct+0x96/0x370 kernel/fork.c:750
 put_task_struct include/linux/sched/task.h:126 [inline]
 delayed_put_task_struct+0x52/0x160 kernel/exit.c:172
 rcu_do_batch kernel/rcu/tree.c:2396 [inline]
 rcu_core+0x606/0xb60 kernel/rcu/tree.c:2623
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2632
 __do_softirq+0x198/0x360 kernel/softirq.c:292
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
 do_softirq_own_stack+0x5d/0x80 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:387 [inline]
 __irq_exit_rcu+0x115/0x120 kernel/softirq.c:417
 sysvec_apic_timer_interrupt+0xd9/0xf0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:596
 arch_local_irq_restore arch/x86/include/asm/paravirt.h:765 [inline]
 kcsan_setup_watchpoint+0x47c/0x4d0 kernel/kcsan/core.c:542
 rcu_preempt_read_exit kernel/rcu/tree_plugin.h:359 [inline]
 __rcu_read_unlock+0x25/0x260 kernel/rcu/tree_plugin.h:392
 rcu_read_unlock include/linux/rcupdate.h:687 [inline]
 inet_twsk_purge+0x3c5/0x400 net/ipv4/inet_timewait_sock.c:299
 dccp_v4_exit_batch+0x16/0x20 net/dccp/ipv4.c:1030
 ops_exit_list net/core/net_namespace.c:189 [inline]
 cleanup_net+0x4dc/0x8c0 net/core/net_namespace.c:603
 process_one_work+0x3cb/0x990 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x210/0x220 kernel/kthread.c:291
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 21 Comm: kworker/u4:1 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
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