Re: [PATCH v3 5/6] xen/arm: unpopulate memory when domain is static

[Julien Grall <julien@xxxxxxx>]

Hi Penny,

On 27/04/2022 11:19, Penny Zheng wrote:
> > > +/*
> > > + * Put free pages on the resv page list after having taken them
> > > + * off the "normal" page list, when pages from static memory  */
> > > +#ifdef CONFIG_STATIC_MEMORY
> > > +#define arch_free_heap_page(d, pg) ({                   \
> > > +    page_list_del(pg, page_to_list(d, pg));             \
> > > +    if ( (pg)->count_info & PGC_reserved )              \
> > > +        page_list_add_tail(pg, &(d)->resv_page_list);   \
> > > +})
> > > +#endif
> > I am a bit puzzled how this is meant to work.
> >
> > Looking at the code, arch_free_heap_page() will be called from
> > free_domheap_pages(). If I am not mistaken, reserved pages are not
> > considered as xen heap pages, so we would go in the else which will end up to
> > call free_heap_pages().
> >
> > free_heap_pages() will end up to add the page in the heap allocator and
> > corrupt the d->resv_page_list because there are only one link list.
> >
> > What did I miss?
> In my first commit "do not free reserved memory into heap", I've changed the 
> behavior
> for reserved pages in free_heap_pages()
> +    if ( pg->count_info & PGC_reserved )
> +        /* Reserved page shall not go back to the heap. */
> +        return free_staticmem_pages(pg, 1UL << order, need_scrub);
> +
Hmmm... somehow this e-mail is neither in my inbox nor in the archives 
on lore.kernel.org.
Cheers,
--
Julien Grall