mm: distinguish CMA and MOVABLE isolation in has_unmovable_pages()
Joonsoo has noticed that "mm: drop migrate type checks from
has_unmovable_pages" would break CMA allocator because it relies on
has_unmovable_pages returning false even for CMA pageblocks which in
fact don't have to be movable:
alloc_contig_range
start_isolate_page_range
set_migratetype_isolate
has_unmovable_pages
This is a result of the code sharing between CMA and memory hotplug
while each one has a different idea of what has_unmovable_pages should
return. This is unfortunate but fixing it properly would require a lot
of code duplication.
Fix the issue by introducing the requested migrate type argument and
special case MIGRATE_CMA case where CMA page blocks are handled
properly. This will work for memory hotplug because it requires
MIGRATE_MOVABLE.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michal Hocko <[email protected]>
Reported-by: Joonsoo Kim <[email protected]>
Tested-by: Stefan Wahren <[email protected]>
Tested-by: Ran Wang <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Igor Mammedov <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Cc: Reza Arbab <[email protected]>
Cc: Vitaly Kuznetsov <[email protected]>
Cc: Xishi Qiu <[email protected]>
Cc: Yasuaki Ishimatsu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e6d4234..755f35f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7353,6 +7353,7 @@ void *__init alloc_large_system_hash(const char *tablename,
* race condition. So you can't expect this function should be exact.
*/
bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
+ int migratetype,
bool skip_hwpoisoned_pages)
{
unsigned long pfn, iter, found;
@@ -7364,6 +7365,15 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
if (zone_idx(zone) == ZONE_MOVABLE)
return false;
+ /*
+ * CMA allocations (alloc_contig_range) really need to mark isolate
+ * CMA pageblocks even when they are not movable in fact so consider
+ * them movable here.
+ */
+ if (is_migrate_cma(migratetype) &&
+ is_migrate_cma(get_pageblock_migratetype(page)))
+ return false;
+
pfn = page_to_pfn(page);
for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {
unsigned long check = pfn + iter;
@@ -7446,7 +7456,7 @@ bool is_pageblock_removable_nolock(struct page *page)
if (!zone_spans_pfn(zone, pfn))
return false;
- return !has_unmovable_pages(zone, page, 0, true);
+ return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE, true);
}
#if (defined(CONFIG_MEMORY_ISOLATION) && defined(CONFIG_COMPACTION)) || defined(CONFIG_CMA)
