[PATCH 1/2] x86,mtrr: Fix original mtrr range get for mtrr_cleanup

[PATCH 1/2] x86,mtrr: Fix original mtrr range get for mtrr_cleanup

[Yinghai Lu]

Joshua reported: Commit cd7b304dfaf1 (x86, range: fix missing merge
during add range) broke mtrr cleanup on his setup in 3.9.5.
corresponding commit in upstream is fbe06b7bae7c.

  *BAD*gran_size: 64K chunk_size: 16M num_reg: 6 lose cover RAM: -0G

https://bugzilla.kernel.org/show_bug.cgi?id=59491

So it rejects new var mtrr layout.

It turns out we have some problem with initial mtrr range retrievel.
current sequence is:
	x86_get_mtrr_mem_range
		==> bunchs of add_range_with_merge
		==> bunchs of subract_range
		==> clean_sort_range
	add_range_with_merge for [0,1M)
	sort_range()

add_range_with_merge could have blank slots, so we can not just
sort only, that will have final result have extra blank slot in head.

So move that calling add_range_with_merge for [0,1M), with that we
could avoid extra clean_sort_range calling.

Reported-by: Joshua Covington <joshuacov@googlemail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: <stable@vger.kernel.org> v3.9

---
 arch/x86/kernel/cpu/mtrr/cleanup.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Index: linux-2.6/arch/x86/kernel/cpu/mtrr/cleanup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/mtrr/cleanup.c
+++ linux-2.6/arch/x86/kernel/cpu/mtrr/cleanup.c
@@ -714,15 +714,15 @@ int __init mtrr_cleanup(unsigned address
 	if (mtrr_tom2)
 		x_remove_size = (mtrr_tom2 >> PAGE_SHIFT) - x_remove_base;
 
-	nr_range = x86_get_mtrr_mem_range(range, 0, x_remove_base, x_remove_size);
 	/*
 	 * [0, 1M) should always be covered by var mtrr with WB
 	 * and fixed mtrrs should take effect before var mtrr for it:
 	 */
 	nr_range = add_range_with_merge(range, RANGE_NUM, nr_range, 0,
 					1ULL<<(20 - PAGE_SHIFT));
-	/* Sort the ranges: */
-	sort_range(range, nr_range);
+	/* add from var mtrr at last */
+	nr_range = x86_get_mtrr_mem_range(range, nr_range,
+					  x_remove_base, x_remove_size);
 
 	range_sums = sum_ranges(range, nr_range);
 	printk(KERN_INFO "total RAM covered: %ldM\n",

[PATCH 2/2] x86, range: make add_range use blank slot

[Yinghai Lu]

Now add_range_with_merge will generate blank slot as subtract_range.
we could reach the array limit because of blank slots.

We can let add_range to have second try to use blank slot.

Also use WARN_ONCE to print trace.

Reported-by: Joshua Covington <joshuacov@googlemail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: <stable@vger.kernel.org> v3.9
---
 kernel/range.c |   34 ++++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 12 deletions(-)

Index: linux-2.6/kernel/range.c
===================================================================
--- linux-2.6.orig/kernel/range.c
+++ linux-2.6/kernel/range.c
@@ -3,23 +3,34 @@
  */
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/bug.h>
 #include <linux/sort.h>
-
 #include <linux/range.h>
 
 int add_range(struct range *range, int az, int nr_range, u64 start, u64 end)
 {
-	if (start >= end)
-		return nr_range;
+	int i;
 
-	/* Out of slots: */
-	if (nr_range >= az)
+	if (start >= end)
 		return nr_range;
 
-	range[nr_range].start = start;
-	range[nr_range].end = end;
+	/* Out of slots ? */
+	if (nr_range < az) {
+		i = nr_range;
+		nr_range++;
+	} else {
+		/* find blank slot */
+		for (i = 0; i < az; i++)
+			if (!range[i].end)
+				break;
+		if (i == az) {
+			WARN_ONCE(1, "run out of slot in ranges\n");
+			return az;
+		}
+	}
 
-	nr_range++;
+	range[i].start = start;
+	range[i].end = end;
 
 	return nr_range;
 }
@@ -98,10 +109,9 @@ void subtract_range(struct range *range,
 			if (i < az) {
 				range[i].end = range[j].end;
 				range[i].start = end;
-			} else {
-				pr_err("%s: run out of slot in ranges\n",
-					__func__);
-			}
+			} else
+				WARN_ONCE(1, "run out of slot in ranges\n");
+
 			range[j].end = start;
 			continue;
 		}