Re: [PATCH 2/2] Futex non-page-pinning fix

[Jamie Lokier]

What happens after this sequence:

	1. process A forks, making process B
	2. B does FUTEX_FD, or splits into threads and one does FUTEX_WAIT,
	   on a private page that has not been written to since the fork
	3. A does FUTEX_WAIT on the same address
	3. The page is swapped out
	4. B does FUTEX_WAKE at the same address

Won't the futex be hashed on the swap entry at step 4, so that
both processes are woken, yet only the waiter in B should be woken?

Related: could COW sharing after fork() explain the spurious wakeups I
saw mentioned earlier in the thread?

-- Jamie
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