On Thu, 15 Oct 2015, Andrea Arcangeli wrote: > get_mergeable_page() can only return NULL (in case of errors) or the > pinned mergeable page. It can't return an error different than > NULL. This makes it more readable and less confusion in addition to > optimizing the check. > > Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> I share your sentiment, prefer to avoid an unnecessary IS_ERR_OR_NULL. And you may be right that it's unnecessary; but that's far from clear to me, and you haven't changed the IS_ERR_OR_NULL after follow_page() in get_mergeable_page() where it originates, so I wonder if you just got confused on this. Even if you have established that there's currently no way that follow_page(vma, addr, FOLL_GET) could return an -errno on a vma validated by find_mergeable_vma(), I think we'd still be better off to allow for some future -errno there; but I'd be happy for you to keep the change below, but also adjust get_mergeable_page() to convert an -errno immediately to NULL after follow_page(). So, I think this is gently Nacked in its present form, but a replacement eagerly Acked. Hugh > --- > mm/ksm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/ksm.c b/mm/ksm.c > index 10618a3..dcefc37 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -1409,7 +1409,7 @@ struct rmap_item *unstable_tree_search_insert(struct rmap_item *rmap_item, > cond_resched(); > tree_rmap_item = rb_entry(*new, struct rmap_item, node); > tree_page = get_mergeable_page(tree_rmap_item); > - if (IS_ERR_OR_NULL(tree_page)) > + if (!tree_page) > return NULL; > > /* -- 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>