Re: [PATCH v5 4/5] mm: Make alloc_contig_range handle in-use hugetlb pages
From: Michal Hocko <mhocko@suse.com>
Date: 2021-03-17 14:27:47
Also in:
lkml
On Wed 17-03-21 12:12:50, Oscar Salvador wrote:
alloc_contig_range() will fail if it finds a HugeTLB page within the range, without a chance to handle them. Since HugeTLB pages can be migrated as any LRU or Movable page, it does not make sense to bail out without trying. Enable the interface to recognize in-use HugeTLB pages so we can migrate them, and have much better chances to succeed the call. Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Mike Kravetz <redacted>
Acked-by: Michal Hocko <mhocko@suse.com> I am still not entirely happy about this
quoted hunk ↗ jump to hunk
@@ -2347,7 +2351,19 @@ int isolate_or_dissolve_huge_page(struct page *page) if (hstate_is_gigantic(h)) return -ENOMEM; - return alloc_and_dissolve_huge_page(h, head); +retry: + if (page_count(head) && isolate_huge_page(head, list)) { + ret = 0; + } else if (!page_count(head)) { + ret = alloc_and_dissolve_huge_page(h, head); + + if (ret == -EBUSY && try_again) { + try_again = false; + goto retry; + } + } + + return ret; }
it would be imho better to retry inside alloc_and_dissolve_huge_page because it already has its retry logic implemented. But not something I will insist on. -- Michal Hocko SUSE Labs