From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Luck, Tony" <tony.luck@intel.com>
Date: Fri, 24 Oct 2003 20:56:31 +0000
Subject: [PATCH 2.4.23-pre8]  Remove broken prefetching in free_one_pgd()
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To: linux-ia64@vger.kernel.org

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);
 }