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BUG: KCSAN: data-race in yama_task_free / yama_task_free

write to 0xffff888121f11050 of 1 bytes by interrupt on cpu 1:
 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:1595
 __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:2414 [inline]
 rcu_core+0x576/0xac0 kernel/rcu/tree.c:2641
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2650
 __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+0xba/0xd0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:587
 should_watch kernel/kcsan/core.c:260 [inline]
 check_access kernel/kcsan/core.c:581 [inline]
 __tsan_read8+0x150/0x180 kernel/kcsan/core.c:777
 anon_vma_chain_alloc mm/rmap.c:136 [inline]
 anon_vma_clone+0x7c/0x380 mm/rmap.c:282
 anon_vma_fork+0x54/0x2b0 mm/rmap.c:345
 dup_mmap+0x4fd/0x9c0 kernel/fork.c:565
 dup_mm+0x7c/0x210 kernel/fork.c:1371
 copy_mm kernel/fork.c:1427 [inline]
 copy_process+0x17a3/0x3300 kernel/fork.c:2098
 _do_fork+0xf1/0x660 kernel/fork.c:2443
 __do_sys_clone kernel/fork.c:2599 [inline]
 __se_sys_clone kernel/fork.c:2580 [inline]
 __x64_sys_clone+0xfb/0x120 kernel/fork.c:2580
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888121f11050 of 1 bytes by interrupt on cpu 0:
 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:1595
 __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:2414 [inline]
 rcu_core+0x576/0xac0 kernel/rcu/tree.c:2641
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2650
 __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+0xba/0xd0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:587
 hlist_bl_first_rcu include/linux/rculist_bl.h:24 [inline]
 __d_lookup+0x62/0x3b0 fs/dcache.c:2388
 lookup_fast+0x67/0x370 fs/namei.c:1502
 walk_component+0x5c/0x350 fs/namei.c:1856
 lookup_last fs/namei.c:2309 [inline]
 path_lookupat+0x12d/0x560 fs/namei.c:2333
 filename_lookup+0xf2/0x380 fs/namei.c:2366
 user_path_at_empty+0x3b/0x50 fs/namei.c:2646
 user_path_at include/linux/namei.h:59 [inline]
 ksys_umount+0xc2/0xa80 fs/namespace.c:1733
 __do_sys_umount fs/namespace.c:1759 [inline]
 __se_sys_umount fs/namespace.c:1757 [inline]
 __x64_sys_umount+0x2c/0x40 fs/namespace.c:1757
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9099 Comm: syz-executor.4 Not tainted 5.8.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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