diff options
| -rw-r--r-- | mm/memremap.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/mm/memremap.c b/mm/memremap.c index 86432650f829..ed70c4e8e52a 100644 --- a/mm/memremap.c +++ b/mm/memremap.c @@ -403,6 +403,30 @@ void __put_devmap_managed_page(struct page *page) mem_cgroup_uncharge(page); + /* + * When a device_private page is freed, the page->mapping field + * may still contain a (stale) mapping value. For example, the + * lower bits of page->mapping may still identify the page as + * an anonymous page. Ultimately, this entire field is just + * stale and wrong, and it will cause errors if not cleared. + * One example is: + * + * migrate_vma_pages() + * migrate_vma_insert_page() + * page_add_new_anon_rmap() + * __page_set_anon_rmap() + * ...checks page->mapping, via PageAnon(page) call, + * and incorrectly concludes that the page is an + * anonymous page. Therefore, it incorrectly, + * silently fails to set up the new anon rmap. + * + * For other types of ZONE_DEVICE pages, migration is either + * handled differently or not done at all, so there is no need + * to clear page->mapping. + */ + if (is_device_private_page(page)) + page->mapping = NULL; + page->pgmap->ops->page_free(page); } else if (!count) __put_page(page); |