On Tue, Jul 07, 2020 at 08:00:11PM +0800, Alex Shi wrote:
>
>
> 在 2020/7/7 下午7:46, Alex Shi 写道:
> >
> > +static void lru_add_page_tail(struct page *page, struct page *page_tail,
> > + struct lruvec *lruvec, struct list_head *list)
> > +{
> > + VM_BUG_ON_PAGE(!PageHead(page), page);
> > + VM_BUG_ON_PAGE(PageCompound(page_tail), page);
> > + VM_BUG_ON_PAGE(PageLRU(page_tail), page);
> > + lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
> > +
> > + if (!list)
> > + SetPageLRU(page_tail);
> > +
> > + if (likely(PageLRU(page)))
> > + list_add_tail(&page_tail->lru, &page->lru);
> > + else if (list) {
> > + /* page reclaim is reclaiming a huge page */
> > + get_page(page_tail);
> > + list_add_tail(&page_tail->lru, list);
> > + } else {
> > + /*
> > + * Head page has not yet been counted, as an hpage,
> > + * so we must account for each subpage individually.
> > + *
> > + * Put page_tail on the list at the correct position
> > + * so they all end up in order.
> > + */
> > + add_page_to_lru_list_tail(page_tail, lruvec,
> > + page_lru(page_tail));
>
>
> I missed some points for this function, since in the call chain:
> split_huge_page() to lru_add_page_tail, the head page's lru won't be
> set when !PageLRU(head). But the other page_tail are add to lru list here
> Is it ok for this situation?
It doesn't differ from the situation when some pages are isolated from
LRU. Tail page has become completely on its own after
__split_huge_page_tail() has completed, it's not tied to the head page.
--
Kirill A. Shutemov
