Commit a8803e6c authored by Wei Yang's avatar Wei Yang Committed by Linus Torvalds
Browse files

mm/huge_memory.c: use head to emphasize the purpose of page 

During split huge page, it checks the property of the page.  Currently
we do the check on page and head without emphasizing the check is on the
compound page.  In case the page passed to split_huge_page_to_list is a
tail page, audience would take some time to think about whether the
check is on compound page or tail page itself.

To make it explicit, use head instead of page for those checks.  After
this, audience would be more clear about the checks are on compound page
and the page is used to do the split and dump error message if failed.

Link: http://lkml.kernel.org/r/20200110032610.26499-2-richardw.yang@linux.intel.com


Signed-off-by: default avatarWei Yang <richardw.yang@linux.intel.com>
Acked-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cb829624

mm/huge_memory.c

+8 −8
Original line number Diff line number Diff line
@@ -2704,7 +2704,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) 
{

	struct page *head = compound_head(page);

	struct pglist_data *pgdata = NODE_DATA(page_to_nid(head));

	struct deferred_split *ds_queue = get_deferred_split_queue(page);

	struct deferred_split *ds_queue = get_deferred_split_queue(head);

	struct anon_vma *anon_vma = NULL;

	struct address_space *mapping = NULL;

	int count, mapcount, extra_pins, ret;
@@ -2713,10 +2713,10 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) 
	pgoff_t end;



	VM_BUG_ON_PAGE(is_huge_zero_page(head), head);

	VM_BUG_ON_PAGE(!PageLocked(page), page);

	VM_BUG_ON_PAGE(!PageCompound(page), page);

	VM_BUG_ON_PAGE(!PageLocked(head), head);

	VM_BUG_ON_PAGE(!PageCompound(head), head);



	if (PageWriteback(page))

	if (PageWriteback(head))

		return -EBUSY;



	if (PageAnon(head)) {
@@ -2767,7 +2767,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) 
		goto out_unlock;

	}



	mlocked = PageMlocked(page);

	mlocked = PageMlocked(head);

	unmap_page(head);

	VM_BUG_ON_PAGE(compound_mapcount(head), head);
@@ -2800,10 +2800,10 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) 
			list_del(page_deferred_list(head));

		}

		if (mapping) {

			if (PageSwapBacked(page))

				__dec_node_page_state(page, NR_SHMEM_THPS);

			if (PageSwapBacked(head))

				__dec_node_page_state(head, NR_SHMEM_THPS);

			else

				__dec_node_page_state(page, NR_FILE_THPS);

				__dec_node_page_state(head, NR_FILE_THPS);

		}



		spin_unlock(&ds_queue->split_queue_lock);

CRA Git | Maintained and supported by SUSTech CRA and CCSE