Xen devel - Nov 2008 - Problem re-alloc''ing after freeing domheap pages

I am trying (in Xen) to repeatedly allocate and free
domheap pages belonging to a pv domain.  However,
once a page is freed, it doesn''t seem to be
allocatable again.  In pseudo-code:

free_up_some_pages_using_ballooning()
count = 0;
while (1) {
  if ((p = alloc_domheap_pages(d,0,0)) == NULL)
    break;
  /* save p someplace */
  count++;
}
for all saved p''s {
  free_domheap_pages(p,0);
}
while (count--) {
  if ((p = alloc_domheap_pages(d,0,0)) == NULL)
    FAIL!!
}

This fails for all alloc''s in the second while loop.

Is there something else I need to do when I allocate
or free a non-anonymous domheap page?  (Note this seems
to work fine for anonymous domheap pages.)

Do I maybe need to also do list_del(&p->list)?  Or
get_page()/put_page() or something like that?

Thanks,
Dan

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On 13/11/08 22:32, "Dan Magenheimer"
<dan.magenheimer@oracle.com> wrote:
> This fails for all alloc''s in the second while loop.
> 
> Is there something else I need to do when I allocate
> or free a non-anonymous domheap page?  (Note this seems
> to work fine for anonymous domheap pages.)
> 
> Do I maybe need to also do list_del(&p->list)?  Or
> get_page()/put_page() or something like that?
What you describe should work as-is. If domain d were dying then the freed
pages would end up on the scrub list rather than the free list, but
that''s
presumably not the case here.

 -- Keir



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