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

write to 0xffff88802d72502c of 4 bytes by task 25915 on cpu 1:
 exit_signals+0x10d/0x540 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:2865
 do_exit+0x1b4/0x1690 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/exit.c:781
 do_group_exit+0xce/0x180 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/exit.c:922
 get_signal+0xdce/0x14e0 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:2773
 arch_do_signal_or_restart+0x2a/0x270 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/kernel/signal.c:811
 handle_signal_work syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x11a/0x1b0 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:201
 irqentry_exit_to_user_mode+0x5/0x20 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:315
 irqentry_exit+0xe/0x40 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/entry/common.c:403
 asm_sysvec_reschedule_ipi+0x12/0x20 syzkaller/managers/upstream-kcsan-gce/kernel/./arch/x86/include/asm/idtentry.h:634

read to 0xffff88802d72502c of 4 bytes by task 13030 on cpu 0:
 sig_task_ignored syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:94 [inline]
 sig_ignored syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:119 [inline]
 prepare_signal+0x872/0xd80 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:962
 __send_signal+0x64/0x790 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:1082
 send_signal+0x398/0x3e0 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:1242
 do_send_sig_info+0x9b/0xe0 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:1291
 group_send_sig_info syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:1414 [inline]
 kill_pid_info+0x7f/0x100 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:1448
 kill_proc_info syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:1465 [inline]
 kill_something_info syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:1562 [inline]
 __do_sys_kill syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:3683 [inline]
 __se_sys_kill+0xd3/0x450 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:3677
 __x64_sys_kill+0x2d/0x40 syzkaller/managers/upstream-kcsan-gce/kernel/kernel/signal.c:3677
 do_syscall_64+0x39/0x80 syzkaller/managers/upstream-kcsan-gce/kernel/arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13030 Comm: syz-executor.3 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================