linux-kernel - [PATCH v2] x86: Fix adjust_range_size

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Date:	Wed, 29 May 2013 14:09:29 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	Yuanhan Liu <yuanhan.liu@...ux.intel.com>,
	linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH v2] x86: Fix adjust_range_size_mask calling position

Commit 8d57470d cause a kernel panic while setting mem=2G.
     [mem 0x00000000-0x000fffff] page 4k
     [mem 0x7fe00000-0x7fffffff] page 1G
     [mem 0x7c000000-0x7fdfffff] page 1G
     [mem 0x00100000-0x001fffff] page 4k
     [mem 0x00200000-0x7bffffff] page 2M

for last entry is not what we want, we should have
     [mem 0x00200000-0x3fffffff] page 2M
     [mem 0x40000000-0x7bffffff] page 1G

Actually we merge the continuous ranges with same page size too early.
in this case, before merging we have
     [mem 0x00200000-0x3fffffff] page 2M
     [mem 0x40000000-0x7bffffff] page 2M
after merging them, will get
     [mem 0x00200000-0x7bffffff] page 2M
even we can use 1G page to map
     [mem 0x40000000-0x7bffffff]

that will cause problem, because we already map
     [mem 0x7fe00000-0x7fffffff] page 1G
     [mem 0x7c000000-0x7fdfffff] page 1G
with 1G page.

Fix that by calling adjust_range_size_mask before merging range
with same page size.

We need this one for v3.9 stable.

-v2: update change log.

Bisected-by: "Xie, ChanglongX" <changlongx.xie@...el.com>
Bisected-by: Yuanhan Liu <yuanhan.liu@...ux.intel.com>
Reported-and-tested-by: Yuanhan Liu <yuanhan.liu@...ux.intel.com>
Signed-off-by: Yinghai Lu <yinghai@...nel.org>

---
 arch/x86/mm/init.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Index: linux-2.6/arch/x86/mm/init.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init.c
+++ linux-2.6/arch/x86/mm/init.c
@@ -277,6 +277,9 @@ static int __meminit split_mem_range(str
 	end_pfn = limit_pfn;
 	nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
 
+	if (!after_bootmem)
+		adjust_range_page_size_mask(mr, nr_range);
+
 	/* try to merge same page size and continuous */
 	for (i = 0; nr_range > 1 && i < nr_range - 1; i++) {
 		unsigned long old_start;
@@ -291,9 +294,6 @@ static int __meminit split_mem_range(str
 		nr_range--;
 	}
 
-	if (!after_bootmem)
-		adjust_range_page_size_mask(mr, nr_range);
-
 	for (i = 0; i < nr_range; i++)
 		printk(KERN_DEBUG " [mem %#010lx-%#010lx] page %s\n",
 				mr[i].start, mr[i].end - 1,
--
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