+ drivers-memory-check-for-missing-sections-when-testing-zones.patch added to -mm tree

+ drivers-memory-check-for-missing-sections-when-testing-zones.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/memory_hotplug.c: check for missing sections when testing zones
has been added to the -mm tree.  Its filename is
     drivers-memory-check-for-missing-sections-when-testing-zones.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/drivers-memory-check-for-missing-sections-when-testing-zones.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/drivers-memory-check-for-missing-sections-when-testing-zones.patch

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------------------------------------------------------
From: Andrew Banman <abanman@sgi.com>
Subject: mm/memory_hotplug.c: check for missing sections when testing zones

test_pages_in_a_zone() does not account for the possibility of missing
sections in the given pfn range.  Since pfn_valid_within always returns 1
when CONFIG_HOLES_IN_ZONE is not set, invalid pfns from missing sections
will pass the test, resulting in a kernel oops.  This is remedied by
simply checking for the presence of the pfn's section.  We don't have to
remove the pfn_valid_within optimization.

The patch also prevents a crash from offlining memory devices with missing
sections.

Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russ Anderson <rja@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory_hotplug.c |    3 +++
 1 file changed, 3 insertions(+)

diff -puN mm/memory_hotplug.c~drivers-memory-check-for-missing-sections-when-testing-zones mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~drivers-memory-check-for-missing-sections-when-testing-zones
+++ a/mm/memory_hotplug.c
@@ -1383,6 +1383,9 @@ int test_pages_in_a_zone(unsigned long s
 	     pfn < end_pfn;
 	     pfn += MAX_ORDER_NR_PAGES) {
 		i = 0;
+		/* Make sure the memory section is present */
+		if (!present_section_nr(pfn_to_section_nr(pfn)))
+			continue;
 		/* This is just a CONFIG_HOLES_IN_ZONE check.*/
 		while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
 			i++;
_

Patches currently in -mm which might be from abanman@sgi.com are

drivers-memory-check-for-missing-sections-when-testing-zones.patch