On 20.07.2022 07:46, Penny Zheng wrote: > Today when a domain unpopulates the memory on runtime, they will always > hand the memory back to the heap allocator. And it will be a problem if domain > is static. > > Pages as guest RAM for static domain shall be reserved to only this domain > and not be used for any other purposes, so they shall never go back to heap > allocator. > > This commit puts reserved pages on the new list resv_page_list only after > having taken them off the "normal" list, when the last ref dropped.
I guess this wording somehow relates to ... > --- a/xen/common/page_alloc.c > +++ b/xen/common/page_alloc.c > @@ -2674,10 +2674,14 @@ void free_domstatic_page(struct page_info *page) > > drop_dom_ref = !domain_adjust_tot_pages(d, -1); > > - spin_unlock_recursive(&d->page_alloc_lock); > - > free_staticmem_pages(page, 1, scrub_debug); > > + /* Add page on the resv_page_list *after* it has been freed. */ > + if ( !drop_dom_ref ) > + page_list_add_tail(page, &d->resv_page_list); ... the conditional used here. I cannot, however, figure why there is this conditional (and said part of the description also doesn't help me figure it out). As an aside: A title prefix of xen/arm: suggests you're mostly touching Arm code. But you're touching exclusively common code here. I for one would almost have skipped this patch (more than once) when deciding which ones (may) want me looking at them. Jan
