mm/page_isolation: fix isolate_single_pageblock() isolation behavior

set_migratetype_isolate() does not allow isolating MIGRATE_CMA pageblocks
unless it is used for CMA allocation.  isolate_single_pageblock() did not
have the same behavior when it is used together with
set_migratetype_isolate() in start_isolate_page_range().  This allows
alloc_contig_range() with migratetype other than MIGRATE_CMA, like
MIGRATE_MOVABLE (used by alloc_contig_pages()), to isolate first and last
pageblock but fail the rest.  The failure leads to changing migratetype of
the first and last pageblock to MIGRATE_MOVABLE from MIGRATE_CMA,
corrupting the CMA region.  This can happen during gigantic page

Like Doug said here:,
for gigantic page allocations, the user would notice no difference,
since the allocation on CMA region will fail as well as it did before. 
But it might hurt the performance of device drivers that use CMA, since
CMA region size decreases.

Fix it by passing migratetype into isolate_single_pageblock(), so that
set_migratetype_isolate() used by isolate_single_pageblock() will prevent
the isolation happening.

Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity")
Signed-off-by: Zi Yan <>
Reported-by: Doug Berger <>
Cc: David Hildenbrand <>
Cc: Doug Berger <>
Cc: Mike Kravetz <>
Cc: <>
Signed-off-by: Andrew Morton <>
1 file changed