Messages in this thread | | | Subject | Re: [PATCH v4 0/4] Make alloc_contig_range handle Hugetlb pages | From | David Hildenbrand <> | Date | Wed, 17 Mar 2021 11:07:00 +0100 |
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On 17.03.21 11:05, Oscar Salvador wrote: > On Wed, Mar 17, 2021 at 10:48:31AM +0100, David Hildenbrand wrote: >>> I was preparing v5, and I wanted to be sure I understood you here. >>> >>> Right you are that the in-use page check can be dropped, as those pages >>> can >>> be migrated away, and the Hugetlb page check can also be dropped since >>> isolate_migratepages_range is now capable of dealing with those kind of >>> pages. >>> >>>> b) Similarly, check for gigantic pages and/or movability/migratability. >>> >>> I lost you here. >>> >>> isolate_or_dissolve_huge_page() already bails out on hugetlb-gigantic >>> pages. >>> >>> Or do you mean to place an upfront check here? (hstate_is_gigantic())? >> >> Yes. But I prefer a) and keeping it simple here -- just doing basic sanity >> checks (online, zone, PageReserved()) that are absolutely necessary. > > Ok, I am probably dense as I understood as if you were lean towards having > a) + b).
Sorry, I meant either a) or b) :)
> > That is what I have as the last patch of the patchset: > > From e97175b7d4970cbdcbafcf8c398f72a571e817b0 Mon Sep 17 00:00:00 2001 > From: Oscar Salvador <osalvador@suse.de> > Date: Thu, 18 Mar 2021 05:03:18 +0100 > Subject: [PATCH] mm,page_alloc: Drop unnecesary checks from > pfn_range_valid_contig > > pfn_range_valid_contig() bails out when it finds an in-use page or a > hugetlb page, among other things. > We can drop the in-use page check since __alloc_contig_pages can migrate > away those pages, and the hugetlb page check can go too since > isolate_migratepages_range is now capable of dealing with hugetlb pages. >
Might want to mention that the existing checks were racy either way :)
> Signed-off-by: Oscar Salvador <osalvador@suse.de> > --- > mm/page_alloc.c | 6 ------ > 1 file changed, 6 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 4cb455355f6d..50d73e68b79e 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8685,12 +8685,6 @@ static bool pfn_range_valid_contig(struct zone *z, unsigned long start_pfn, > > if (PageReserved(page)) > return false; > - > - if (page_count(page) > 0) > - return false; > - > - if (PageHuge(page)) > - return false; > } > return true; > } >
-- Thanks,
David / dhildenb
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