syzbot

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BUG: KCSAN: data-race in copy_process / proc_task_readdir

write to 0xffff8881348dfb08 of 4 bytes by task 13729 on cpu 1:
 copy_process+0x228b/0x2fd0 kernel/fork.c:2387
 kernel_clone+0x15c/0x6a0 kernel/fork.c:2582
 __do_sys_clone kernel/fork.c:2699 [inline]
 __se_sys_clone kernel/fork.c:2683 [inline]
 __x64_sys_clone+0xc6/0xf0 kernel/fork.c:2683
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881348dfb08 of 4 bytes by task 13730 on cpu 0:
 get_nr_threads include/linux/sched/signal.h:679 [inline]
 first_tid fs/proc/base.c:3739 [inline]
 proc_task_readdir+0x32d/0x6f0 fs/proc/base.c:3802
 iterate_dir+0x174/0x3c0 fs/readdir.c:65
 __do_sys_getdents fs/readdir.c:286 [inline]
 __se_sys_getdents+0x8e/0x1a0 fs/readdir.c:271
 __x64_sys_getdents+0x3f/0x50 fs/readdir.c:271
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000005 -> 0x00000006

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13730 Comm: syz-executor.0 Not tainted 5.16.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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