Re: X-freeze after clflush changes [Was: 2.6.23-rc6-mm1]

Andrew Morton
2007-09-19T19:10:38Z

On Wed, 19 Sep 2007 16:59:04 +0200 Jiri Slaby <jirislaby@gmail.com> wrote:

> ---------8<---------8<---------8<---------8<---------8<---------8<----
> That means
> void agp_generic_destroy_page(void *addr)
> {
> struct page *page;
>
> if (addr == NULL)
> return;
>
> page = virt_to_page(addr);
> (1) unmap_page_from_agp(page);
> put_page(page);
> (2) free_page((unsigned long)addr);
> atomic_dec(&agp_bridge->current_memory_agp);
> }
>
> (1) unmap_page_from_agp -> change_page_attr -> change_page_attr_addr ->
> __change_page_attr -> save_page -> list_add(&fpage->lru, &deferred_pages);
> (2) free_page -> free_pages -> __free_pages -> free_hot_page ->
> free_hot_cold_page -> list_add(&page->lru, &pcp->list);

that'll hurt.

> any ideas how to fix this?

We should hold a single reference on the page for its membership in
deferred_pages.