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authorAndrew Banman <abanman@sgi.com>2015-12-29 14:54:25 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-12-29 17:45:49 -0800
commit5f0f2887f4de9508dcf438deab28f1de8070c271 (patch)
tree00b2343ccdfd201a3cd19acc26d1460715c01a51 /mm
parentb5a8bc338e68d5f6f753e14ae59b30e75a5ffdde (diff)
downloadlwn-5f0f2887f4de9508dcf438deab28f1de8070c271.tar.gz
lwn-5f0f2887f4de9508dcf438deab28f1de8070c271.zip
mm/memory_hotplug.c: check for missing sections in test_pages_in_a_zone()
test_pages_in_a_zone() does not account for the possibility of missing sections in the given pfn range. pfn_valid_within always returns 1 when CONFIG_HOLES_IN_ZONE is not set, allowing invalid pfns from missing sections to pass the test, leading to a kernel oops. Wrap an additional pfn loop with PAGES_PER_SECTION granularity to check for missing sections before proceeding into the zone-check code. This also prevents a crash from offlining memory devices with missing sections. Despite this, it may be a good idea to keep the related patch '[PATCH 3/3] drivers: memory: prohibit offlining of memory blocks with missing sections' because missing sections in a memory block may lead to other problems not covered by the scope of this fix. Signed-off-by: Andrew Banman <abanman@sgi.com> Acked-by: Alex Thorlton <athorlton@sgi.com> Cc: Russ Anderson <rja@sgi.com> Cc: Alex Thorlton <athorlton@sgi.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Greg KH <greg@kroah.com> Cc: Seth Jennings <sjennings@variantweb.net> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/memory_hotplug.c31
1 files changed, 19 insertions, 12 deletions
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 67d488ab495e..a042a9d537bb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1375,23 +1375,30 @@ int is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
*/
int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
{
- unsigned long pfn;
+ unsigned long pfn, sec_end_pfn;
struct zone *zone = NULL;
struct page *page;
int i;
- for (pfn = start_pfn;
+ for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn);
pfn < end_pfn;
- pfn += MAX_ORDER_NR_PAGES) {
- i = 0;
- /* This is just a CONFIG_HOLES_IN_ZONE check.*/
- while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
- i++;
- if (i == MAX_ORDER_NR_PAGES)
+ pfn = sec_end_pfn + 1, sec_end_pfn += PAGES_PER_SECTION) {
+ /* Make sure the memory section is present first */
+ if (!present_section_nr(pfn_to_section_nr(pfn)))
continue;
- page = pfn_to_page(pfn + i);
- if (zone && page_zone(page) != zone)
- return 0;
- zone = page_zone(page);
+ for (; pfn < sec_end_pfn && pfn < end_pfn;
+ pfn += MAX_ORDER_NR_PAGES) {
+ i = 0;
+ /* This is just a CONFIG_HOLES_IN_ZONE check.*/
+ while ((i < MAX_ORDER_NR_PAGES) &&
+ !pfn_valid_within(pfn + i))
+ i++;
+ if (i == MAX_ORDER_NR_PAGES)
+ continue;
+ page = pfn_to_page(pfn + i);
+ if (zone && page_zone(page) != zone)
+ return 0;
+ zone = page_zone(page);
+ }
}
return 1;
}