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BUG: KCSAN: data-race in forget_original_parent / task_is_descendant.part.0

write to 0xffff8880a80a54bc of 4 bytes by task 18792 on cpu 1:
 reparent_leader kernel/exit.c:578 [inline]
 forget_original_parent+0x510/0x980 kernel/exit.c:630
 exit_notify kernel/exit.c:646 [inline]
 do_exit+0xdd2/0x1150 kernel/exit.c:816
 do_group_exit+0xae/0x1a0 kernel/exit.c:893
 get_signal+0x2a7/0x1290 kernel/signal.c:2739
 do_signal+0x2b/0x840 arch/x86/kernel/signal.c:784
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:161
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x38b/0x3b0 arch/x86/entry/common.c:305
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a80a54bc of 4 bytes by task 18793 on cpu 0:
 thread_group_leader include/linux/sched/signal.h:654 [inline]
 task_is_descendant.part.0+0x3f/0x170 security/yama/yama_lsm.c:282
 task_is_descendant security/yama/yama_lsm.c:278 [inline]
 yama_ptrace_access_check security/yama/yama_lsm.c:369 [inline]
 yama_ptrace_access_check+0x198/0x405 security/yama/yama_lsm.c:354
 security_ptrace_access_check+0x5f/0x90 security/security.c:749
 __ptrace_may_access+0x23a/0x390 kernel/ptrace.c:351
 ptrace_attach+0x179/0x460 kernel/ptrace.c:399
 __do_sys_ptrace kernel/ptrace.c:1262 [inline]
 __se_sys_ptrace kernel/ptrace.c:1242 [inline]
 __x64_sys_ptrace+0x226/0x270 kernel/ptrace.c:1242
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18793 Comm: syz-executor.2 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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