syzbot

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BUG: KCSAN: data-race in futex_wait_queue_me / task_dump_owner

write to 0xffff8881003140ac of 4 bytes by task 11648 on cpu 0:
 freezer_do_not_count include/linux/freezer.h:109 [inline]
 freezable_schedule include/linux/freezer.h:171 [inline]
 futex_wait_queue_me+0x198/0x260 kernel/futex.c:2606
 futex_wait+0x143/0x430 kernel/futex.c:2708
 do_futex+0x9d8/0x1ee0 kernel/futex.c:3732
 __do_sys_futex kernel/futex.c:3805 [inline]
 __se_sys_futex+0x21c/0x380 kernel/futex.c:3786
 __x64_sys_futex+0x74/0x80 kernel/futex.c:3786
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881003140ac of 4 bytes by task 11651 on cpu 1:
 task_dump_owner+0x2b/0x1d0 fs/proc/base.c:1822
 proc_pid_make_inode+0x1d6/0x200 fs/proc/base.c:1918
 proc_fd_instantiate+0x32/0x160 fs/proc/fd.c:178
 proc_lookupfd_common fs/proc/fd.c:210 [inline]
 proc_lookupfd+0xa2/0x150 fs/proc/fd.c:272
 lookup_open fs/namei.c:3193 [inline]
 open_last_lookups fs/namei.c:3285 [inline]
 path_openat+0xb5a/0x20b0 fs/namei.c:3491
 do_filp_open+0xd9/0x1f0 fs/namei.c:3521
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_openat fs/open.c:1219 [inline]
 __se_sys_openat fs/open.c:1214 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1214
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11651 Comm: syz-executor.3 Not tainted 5.13.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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