==================================================================
BUG: KCSAN: data-race in do_msgsnd / do_signal_stop

write to 0xffff8881208e80d0 of 8 bytes by task 16276 on cpu 1:
 ss_add ipc/msg.c:201 [inline]
 do_msgsnd+0x675/0xc50 ipc/msg.c:897
 ksys_msgsnd ipc/msg.c:958 [inline]
 __do_sys_msgsnd ipc/msg.c:964 [inline]
 __se_sys_msgsnd ipc/msg.c:961 [inline]
 __x64_sys_msgsnd+0x85/0xb0 ipc/msg.c:961
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881208e80d0 of 8 bytes by task 16271 on cpu 0:
 do_signal_stop+0x3cc/0x4e0 kernel/signal.c:2348
 get_signal+0x601/0x1290 kernel/signal.c:2694
 do_signal+0x2b/0x670 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16271 Comm: syz-executor.1 Not tainted 5.6.0-rc1-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: 0 PID: 16271 Comm: syz-executor.1 Not tainted 5.6.0-rc1-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+0x11d/0x187 lib/dump_stack.c:118
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0x14 kernel/kcsan/report.c:556
 kcsan_setup_watchpoint+0x304/0x400 kernel/kcsan/core.c:495
 do_signal_stop+0x3cc/0x4e0 kernel/signal.c:2348
 get_signal+0x601/0x1290 kernel/signal.c:2694
 do_signal+0x2b/0x670 arch/x86/kernel/signal.c:813
 exit_to_usermode_loop+0x24a/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x416011
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffd7d196150 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: fffffffffffffff7 RBX: 0000000000000005 RCX: 0000000000416011
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 0000000000000000 R08: 01ffffffffffffff R09: 01ffffffffffffff
R10: 00007ffd7d196230 R11: 0000000000000293 R12: 000000000076c100
R13: 0000000000770e08 R14: 000000000007166d R15: 000000000076c10c
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..