syzbot

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BUG: KCSAN: data-race in do_task_stat / get_signal

read to 0xffff8880a14ee7a0 of 8 bytes by task 24942 on cpu 1:
 do_task_stat+0xad3/0x1450 fs/proc/array.c:574
 proc_tgid_stat+0x3d/0x60 fs/proc/array.c:632
 proc_single_show+0x92/0x120 fs/proc/base.c:756
 seq_read+0x350/0x9d0 fs/seq_file.c:229
 __vfs_read+0x67/0xc0 fs/read_write.c:425
 vfs_read fs/read_write.c:461 [inline]
 vfs_read+0x143/0x2c0 fs/read_write.c:446
 ksys_read+0xd5/0x1b0 fs/read_write.c:587
 __do_sys_read fs/read_write.c:597 [inline]
 __se_sys_read fs/read_write.c:595 [inline]
 __x64_sys_read+0x4c/0x60 fs/read_write.c:595
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880a14ee7a0 of 8 bytes by task 18179 on cpu 0:
 sigdelset include/linux/signal.h:67 [inline]
 dequeue_synchronous_signal kernel/signal.c:734 [inline]
 get_signal+0xbc9/0x1320 kernel/signal.c:2622
 do_signal+0x2f/0x6c0 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode+0x1a6/0x1d0 arch/x86/entry/common.c:195
 swapgs_restore_regs_and_return_to_usermode+0x0/0x40

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18179 Comm: syz-executor.2 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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