x86, mtrr: Fix original mtrr range get for mtrr_cleanup

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 retrieval.
The 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>
Tested-by: Joshua Covington <joshuacov@googlemail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1371154622-8929-2-git-send-email-yinghai@kernel.org
Cc: <stable@vger.kernel.org> v3.9
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c b/arch/x86/kernel/cpu/mtrr/cleanup.c
index 35ffda5..5f90b85 100644 (file)
--- a/arch/x86/kernel/cpu/mtrr/cleanup.c
+++ b/arch/x86/kernel/cpu/mtrr/cleanup.c
@@ -714,15 +714,15 @@ int __init mtrr_cleanup(unsigned address_bits)
        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",