==================================================================
BUG: KCSAN: data-race in futex_wait_queue_me / prepare_signal

write to 0xffff88812764a02c of 4 bytes by task 7127 on cpu 1:
 freezer_count include/linux/freezer.h:121 [inline]
 freezable_schedule include/linux/freezer.h:173 [inline]
 futex_wait_queue_me+0x1ba/0x260 kernel/futex.c:2606
 futex_wait+0x143/0x430 kernel/futex.c:2708
 do_futex+0x9d8/0x1ee0 kernel/futex.c:3732
 __do_sys_futex kernel/futex.c:3805 [inline]
 __se_sys_futex+0x21c/0x380 kernel/futex.c:3786
 __x64_sys_futex+0x74/0x80 kernel/futex.c:3786
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812764a02c of 4 bytes by task 7121 on cpu 0:
 sig_task_ignored kernel/signal.c:93 [inline]
 sig_ignored kernel/signal.c:118 [inline]
 prepare_signal+0x952/0xeb0 kernel/signal.c:1001
 __send_signal+0x64/0x760 kernel/signal.c:1121
 send_signal+0x281/0x390 kernel/signal.c:1283
 __group_send_sig_info kernel/signal.c:1322 [inline]
 do_notify_parent_cldstop+0x222/0x280 kernel/signal.c:2104
 ptrace_stop+0x2e2/0x670 kernel/signal.c:2238
 ptrace_do_notify kernel/signal.c:2305 [inline]
 ptrace_notify+0x107/0x180 kernel/signal.c:2315
 ptrace_report_syscall include/linux/tracehook.h:66 [inline]
 tracehook_report_syscall_entry include/linux/tracehook.h:105 [inline]
 arch_syscall_enter_tracehook include/linux/entry-common.h:98 [inline]
 syscall_trace_enter+0x87/0x290 kernel/entry/common.c:60
 __syscall_enter_from_user_work kernel/entry/common.c:89 [inline]
 syscall_enter_from_user_mode+0x1c/0x20 kernel/entry/common.c:107
 do_syscall_64+0x27/0x90 arch/x86/entry/common.c:42
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7121 Comm: syz-executor.0 Not tainted 5.13.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================