Is there a reason we call unmap_mapping_range() for a single page at a time instead of the entire hugepage? This is surely more efficient ... but does it do something like increase the refcount on the page? I suppose we might be able to skip all the calls to unmap_mapping_range() if none of the pages are mapped, but surely anonymous pages are usually mapped? diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 34bce5c308e3..2c686ba6a32b 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1396,17 +1396,11 @@ static void collapse_shmem(struct mm_struct *mm, goto out_isolate_failed; } - if (page_mapped(page)) - unmap_mapping_range(mapping, index << PAGE_SHIFT, - PAGE_SIZE, 0); - spin_lock_irq(&mapping->tree_lock); slot = radix_tree_lookup_slot(&mapping->page_tree, index); VM_BUG_ON_PAGE(page != radix_tree_deref_slot_protected(slot, &mapping->tree_lock), page); - VM_BUG_ON_PAGE(page_mapped(page), page); - /* * The page is expected to have page_count() == 3: * - we hold a pin on it; @@ -1472,6 +1466,9 @@ static void collapse_shmem(struct mm_struct *mm, unsigned long flags; struct zone *zone = page_zone(new_page); + unmap_mapping_range(mapping, start << PAGE_SHIFT, + HPAGE_PMD_SIZE, 0); + /* * Replacing old pages with new one has succeed, now we need to * copy the content and free old pages. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
