On Tue, 13 Sep 2022 22:39:13 -0400 Zi Yan <zi.yan@xxxxxxxx> wrote: > 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 > allocations. How does this bug manifest itself as far as the user is concerned? > Fix it by passing migratetype into isolate_single_pageblock(), so that > set_migratetype_isolate() used by isolate_single_pageblock() will prevent > the isolation happening.
