[PATCH 2.4.23-pre8] Remove broken prefetching in free_one_pgd()

["Luck, Tony" <tony.luck@intel.com>]

This patch was accepted into 2.5.55, attributed to "davej@uk".

This code will prefetch from beyond the end of the page table
being cleared ... which is clearly a bad thing if the page table
in question is allocated from the last page of memory (or precedes
a hole on a discontig mem system).

-Tony Luck

diff -ru linux-2.4.23-pre8/mm/memory.c fix/mm/memory.c
--- linux-2.4.23-pre8/mm/memory.c	Fri Oct 24 13:37:23 2003
+++ fix/mm/memory.c	Fri Oct 24 13:40:47 2003
@@ -120,10 +120,8 @@
 	}
 	pmd = pmd_offset(dir, 0);
 	pgd_clear(dir);
-	for (j = 0; j < PTRS_PER_PMD ; j++) {
-		prefetchw(pmd+j+(PREFETCH_STRIDE/16));
+	for (j = 0; j < PTRS_PER_PMD ; j++)
 		free_one_pmd(pmd+j);
-	}
 	pmd_free(pmd);
 }