==================================================================
BUG: KCSAN: data-race in syscall_trace_enter / zap_other_threads

write to 0xffff88806f5d4778 of 8 bytes by task 1644 on cpu 0:
 sigaddset include/linux/signal.h:66 [inline]
 zap_other_threads+0x116/0x1e0 kernel/signal.c:1361
 do_group_exit+0x146/0x180 kernel/exit.c:898
 __do_sys_exit_group+0xb/0x10 kernel/exit.c:914
 __se_sys_exit_group+0x5/0x10 kernel/exit.c:912
 __x64_sys_exit_group+0x16/0x20 kernel/exit.c:912
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88806f5d4778 of 8 bytes by task 1645 on cpu 1:
 sigismember include/linux/signal.h:84 [inline]
 __fatal_signal_pending include/linux/sched/signal.h:363 [inline]
 fatal_signal_pending include/linux/sched/signal.h:368 [inline]
 ptrace_report_syscall include/linux/tracehook.h:79 [inline]
 tracehook_report_syscall_entry include/linux/tracehook.h:104 [inline]
 arch_syscall_enter_tracehook include/linux/entry-common.h:108 [inline]
 syscall_trace_enter+0xd9/0x2b0 kernel/entry/common.c:51
 __syscall_enter_from_user_work kernel/entry/common.c:79 [inline]
 syscall_enter_from_user_mode+0x2d/0x40 kernel/entry/common.c:97
 do_syscall_64+0x11/0x80 arch/x86/entry/common.c:41
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1645 Comm: syz-executor.1 Not tainted 5.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 1645 Comm: syz-executor.1 Not tainted 5.9.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x10f/0x19d lib/dump_stack.c:118
 panic+0x207/0x64a kernel/panic.c:231
 kcsan_report+0x684/0x690 kernel/kcsan/report.c:630
 kcsan_setup_watchpoint+0x41e/0x4a0 kernel/kcsan/core.c:540
 sigismember include/linux/signal.h:84 [inline]
 __fatal_signal_pending include/linux/sched/signal.h:363 [inline]
 fatal_signal_pending include/linux/sched/signal.h:368 [inline]
 ptrace_report_syscall include/linux/tracehook.h:79 [inline]
 tracehook_report_syscall_entry include/linux/tracehook.h:104 [inline]
 arch_syscall_enter_tracehook include/linux/entry-common.h:108 [inline]
 syscall_trace_enter+0xd9/0x2b0 kernel/entry/common.c:51
 __syscall_enter_from_user_work kernel/entry/common.c:79 [inline]
 syscall_enter_from_user_mode+0x2d/0x40 kernel/entry/common.c:97
 do_syscall_64+0x11/0x80 arch/x86/entry/common.c:41
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x0
Code: Bad RIP value.
RSP: 002b:00007fae32cfdc78 EFLAGS: 00000346 ORIG_RAX: 000000000000002b
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200006c0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..