[PATCH v3 1/2] x86, mtrr: Fix original mtrr range get for mtrr_cleanup

From: Yinghai Lu
Date: Thu Jun 13 2013 - 16:17:49 EST

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


So it rejects new var mtrr layout.

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

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@xxxxxxxxxxxxxx>
Tested-by: Joshua Covington <joshuacov@xxxxxxxxxxxxxx>
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> v3.9

arch/x86/kernel/cpu/mtrr/cleanup.c | 8 ++++----
1 file changed, 4 insertions(+), 4 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,
+ nr_range = add_range_with_merge(range, RANGE_NUM, 0, 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",
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/