On Thu, Feb 09, 2017 at 12:14:16PM -0800, Matthew Wilcox wrote: > On Thu, Jan 26, 2017 at 02:57:47PM +0300, Kirill A. Shutemov wrote: > > @@ -2146,6 +2146,23 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) > > goto out; > > } > > > > + /* Try to free buffers before attempt split */ > > + if (!PageSwapBacked(head) && PagePrivate(page)) { > > + /* > > + * We cannot trigger writeback from here due possible > > + * recursion if triggered from vmscan, only wait. > > + * > > + * Caller can trigger writeback it on its own, if safe. > > + */ > > It took me a few reads to get this. May I suggest: > > /* > * Cannot split a page with buffers. If the caller has > * already started writeback, we can wait for it to finish, > * but we cannot start writeback if we were called from vmscan > */ Yeah, that's better. > > + if (!PageSwapBacked(head) && PagePrivate(page)) { > > Also, it looks weird to test PageSwapBacked of *head* and PagePrivate > of *page*. I think it's correct, but it still looks weird. I'll change this. > Reviewed-by: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx> Thanks! -- Kirill A. Shutemov