Re: [PATCH v3 2/2] mm: Make alloc_contig_range handle in-use hugetlb pages
From: Michal Hocko <mhocko@suse.com>
Date: 2021-02-26 08:48:12
Also in:
lkml
On Mon 22-02-21 14:51:37, Oscar Salvador wrote: [...]
quoted hunk ↗ jump to hunk
@@ -2394,9 +2397,19 @@ bool isolate_or_dissolve_huge_page(struct page *page) */ if (hstate_is_gigantic(h)) return ret; - - if (!page_count(head) && alloc_and_dissolve_huge_page(h, head)) +retry: + if (page_count(head) && isolate_huge_page(head, list)) { ret = true; + } else if (!page_count(head)) {
This is rather head spinning. Do we need to test page_count in the else branch? Do you want to optimize for a case where the page cannot be isolated because of page_huge_active?
+ int err = alloc_and_dissolve_huge_page(h, head);
+
+ if (!err) {
+ ret = true;
+ } else if (err == -EBUSY && try_again) {
+ try_again = false;
+ goto retry;
+ }Is this retry once logic really needed? Does it really give us any real benefit? alloc_and_dissolve_huge_page already retries when the page is being freed. -- Michal Hocko SUSE Labs