linux-kernel - [PATCH] memblock: Make sure reserved.regions is freed really

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Date:	Fri, 15 Jun 2012 20:12:11 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Tejun Heo <tj@...nel.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH] memblock: Make sure reserved.regions is freed really

memblock_free() would double reserved.regions too, so we could free
old range for reserved.regions.

So need to check that regions get doubled. If it is doubled, we need to
free it.

Cc: Tejun Heo <tj@...nel.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Yinghai Lu <yinghai@...nel.org>

---
 mm/memblock.c |   23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

Index: linux-2.6/mm/memblock.c
===================================================================
--- linux-2.6.orig/mm/memblock.c
+++ linux-2.6/mm/memblock.c
@@ -148,11 +148,26 @@ phys_addr_t __init_memblock memblock_fin
  */
 int __init_memblock memblock_free_reserved_regions(void)
 {
+	struct memblock_region *r;
+	int ret;
+
 	if (memblock.reserved.regions == memblock_reserved_init_regions)
 		return 0;
 
-	return memblock_free(__pa(memblock.reserved.regions),
-		 sizeof(struct memblock_region) * memblock.reserved.max);
+	/*
+	 * During memblock_free, reserved.regions could be doubled,
+	 * try to check with old one for checking, and need to free the new one.
+	 */
+	do {
+		r = memblock.reserved.regions;
+		ret = memblock_free(__pa(memblock.reserved.regions),
+			sizeof(struct memblock_region) * memblock.reserved.max);
+
+		if (ret)
+			break;
+	} while (memblock.reserved.regions != r);
+
+	return ret;
 }
 
 /*
@@ -163,6 +178,10 @@ int __init_memblock memblock_reserve_res
 	if (memblock.reserved.regions == memblock_reserved_init_regions)
 		return 0;
 
+	/*
+	 * Don't need to worry about if reserved.regions get updated later,
+	 * and it is big enough after memblock_free_reserved_regions().
+	 */
 	return memblock_reserve(__pa(memblock.reserved.regions),
 		 sizeof(struct memblock_region) * memblock.reserved.max);
 }
--
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