From b5db0e38653bfada34a92f360b4111566ede3842 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 15 Jan 2009 15:32:12 -0800
Subject: Revert "x86 PAT: remove CPA WARN_ON for zero pte"

This reverts commit 58dab916dfb57328d50deb0aa9b3fc92efa248ff, which
makes my Nehalem come to a nasty crawling almost-halt.  It looks like it
turns off caching of regular kernel RAM, with the understandable
slowdown of a few orders of magnitude as a result.

Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/x86/mm/pageattr.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

(limited to 'arch/x86/mm/pageattr.c')

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 4cf30dee816..e89d24815f2 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -555,12 +555,10 @@ repeat:
 	if (!pte_val(old_pte)) {
 		if (!primary)
 			return 0;
-
-		/*
-		 *  Special error value returned, indicating that the mapping
-		 * did not exist at this address.
-		 */
-		return -EFAULT;
+		WARN(1, KERN_WARNING "CPA: called for zero pte. "
+		       "vaddr = %lx cpa->vaddr = %lx\n", address,
+		       *cpa->vaddr);
+		return -EINVAL;
 	}
 
 	if (level == PG_LEVEL_4K) {
-- 
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