On 1/10/23 6:00 PM, Mike Kravetz wrote:
On 01/10/23 21:40, Matthew Wilcox wrote:
On Tue, Jan 10, 2023 at 03:28:21PM -0600, Sidhartha Kumar wrote:
@@ -3505,6 +3505,7 @@ static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
{
int nr_nodes, node;
struct page *page;
+ struct folio *folio;
lockdep_assert_held(&hugetlb_lock);
@@ -3518,8 +3519,8 @@ static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed)
list_for_each_entry(page, &h->hugepage_freelists[node], lru) {
if (PageHWPoison(page))
continue;
-
- return demote_free_huge_page(h, page);
+ folio = page_folio(page);
+ return demote_free_hugetlb_folio(h, folio);
}
}
Can't this be
list_for_each_entry(folio, &h->hugepage_freelists[node], lru)
which avoids the call to page_folio() here.
I think the call to PageHWPoison is actually wrong here. That would
only check the hwpoison bit on the first page, whereas we want to know
about the hwpoison bit on any page (don't we?) So this should be
folio_test_has_hwpoisoned()?
Or is that a THP-thing that is different for hugetlb pages?
I believe it is different for hugetlb pages. See hugetlb_set_page_hwpoison()
where it sets PageHWPoison on head page as well as allocating a raw_hwp_page
I agree, this line in hugetlb_set_page_hwpoison (which is now
folio_set_hugetlb_hwpoison) sets the HWPoison flag on the head page
int ret = folio_test_set_hwpoison(folio) ? -EHWPOISON : 0;
so the correct code in demote_pool_huge_page() would be:
list_for_each_entry(folio, &h->hugepage_freelists[node], lru) {
if (folio_test_hwpoison(folio))
continue;
return demote_free_hugetlb_folio(h, folio);
}
to track the actual page with poison. Note that we can not directly flag
hugetlb 'subpages' because we may not have the struct pages due to vmemmap
optimization. Adding Naoya just to be sure.
Do agree that this could be list_for_each_entry(folio ...
Will make this change in v3.
Thanks,
Sidhartha Kumar
