4.2.8-ckt2 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Andrew Banman <abanman@xxxxxxx>
commit 5f0f2887f4de9508dcf438deab28f1de8070c271 upstream.
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@xxxxxxx>
Acked-by: Alex Thorlton <athorlton@xxxxxxx>
Cc: Russ Anderson <rja@xxxxxxx>
Cc: Alex Thorlton <athorlton@xxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Cc: Seth Jennings <sjennings@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 31 +++++++++++++++++++------------
1 file changed, 19 insertions(+), 12 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 8fd97da..5860ef1 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1354,23 +1354,30 @@ 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;
}
--
1.9.1
--
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