revert "proc: clear_refs: do not clear reserved pages"

Revert commit 85e72aa5 ("proc: clear_refs: do not clear reserved
pages"), which was a quick fix suitable for -stable until ARM had been
moved over to the gate_vma mechanism:

https://lkml.org/lkml/2012/1/14/55

With commit f9d4861f ("ARM: 7294/1: vectors: use gate_vma for vectors user
mapping"), ARM does now use the gate_vma, so the PageReserved check can be
removed from the proc code.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Nicolas Pitre <nico@linaro.org>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/task_mmu.c

@@ -597,9 +597,6 @@ static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
 		if (!page)
 			continue;
 
-		if (PageReserved(page))
-			continue;
-
 		/* Clear accessed and referenced bits. */
 		ptep_test_and_clear_young(vma, addr, pte);
 		ClearPageReferenced(page);