Re: memory-hotplug : suppres "Trying to free nonexistent resource <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>" warning

On Tue, 9 Oct 2012 11:51:38 +0900
Yasuaki Ishimatsu [off-list ref] wrote:

quoted

Anyway, please have a think, and see if we can come up with the best
and most accurate choice of types and identifiers in this code.

Your concern is right. Overflow bug may occur in the future.
So I changed type of "i" and "sections_to_remove" to "unsigned long".
Please merge it into your tree instead of previous patch.

Too late, the original patch was merged.  So I generated the delta.

I remain allergic to the `i' identifier so I renamed it to `section'. 
That's not 100% accurate, but it is better.

__remove_pages() also has same concern. So I'll fix it.

Thanks.



From: Yasuaki Ishimatsu <redacted>
Subject: arch/powerpc/platforms/pseries/hotplug-memory.c: section removal cleanups

Followups to d760afd4d25 ("memory-hotplug: suppress "Trying to free
nonexistent resource <XXXXXXXXXXXXXXXX-YYYYYYYYYYYYYYYY>" warning").

- use unsigned long type, as overflows are conceivable

- rename `i' to the less-misleading and more informative `section'

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/powerpc/platforms/pseries/hotplug-memory.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff -puN arch/powerpc/platforms/pseries/hotplug-memory.c~arch-powerpc-platforms-pseries-hotplug-memoryc-section-removal-cleanups arch/powerpc/platforms/pseries/hotplug-memory.c

--- a/arch/powerpc/platforms/pseries/hotplug-memory.c~arch-powerpc-platforms-pseries-hotplug-memoryc-section-removal-cleanups
+++ a/arch/powerpc/platforms/pseries/hotplug-memory.c

@@ -77,8 +77,9 @@ static int pseries_remove_memblock(unsig
 {
 	unsigned long start, start_pfn;
 	struct zone *zone;
-	int i, ret;
-	int sections_to_remove;
+	int ret;
+	unsigned long section;
+	unsigned long sections_to_remove;
 
 	start_pfn = base >> PAGE_SHIFT;
 

@@ -99,8 +100,8 @@ static int pseries_remove_memblock(unsig
 	 * while writing to it. So we have to defer it to here.
 	 */
 	sections_to_remove = (memblock_size >> PAGE_SHIFT) / PAGES_PER_SECTION;
-	for (i = 0; i < sections_to_remove; i++) {
-		unsigned long pfn = start_pfn + i * PAGES_PER_SECTION;
+	for (section = 0; section < sections_to_remove; section++) {
+		unsigned long pfn = start_pfn + section * PAGES_PER_SECTION;
 		ret = __remove_pages(zone, start_pfn,  PAGES_PER_SECTION);
 		if (ret)
 			return ret;

diff -puN mm/memory_hotplug.c~arch-powerpc-platforms-pseries-hotplug-memoryc-section-removal-cleanups mm/memory_hotplug.c
_