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I'm inclined to just drop the patch and to ask that issue be > reopened. > > Comments? > > Thanks. > > > From: Wei Yang > Subject: mm/compaction: fix low_pfn advance on isolating hugetlb > Date: Wed, 10 Sep 2025 09:22:40 +0000 > > Commit 56ae0bb349b4 ("mm: compaction: convert to use a folio in > isolate_migratepages_block()") converts api from page to folio. But th= e > low_pfn advance for hugetlb page seems wrong when low_pfn doesn't point= to > head page. > > Originally, if page is a hugetlb tail page, compound_nr() return 1, whi= ch > means low_pfn only advance one in next iteration. After the change, > low_pfn would advance more than the hugetlb range, since folio_nr_pages= () > always return total number of the large page. This results in skipping= > some range to isolate and then to migrate. > > The worst case for alloc_contig is it does all the isolation and > migration, but finally find some range is still not isolated. And then= > undo all the work and try a new range. > > Advance low_pfn to the end of hugetlb. > > Link: https://lkml.kernel.org/r/20250910092240.3981-1-richard.weiyang@g= mail.com > Fixes: 56ae0bb349b4 ("mm: compaction: convert to use a folio in isolate= _migratepages_block()") > Signed-off-by: Wei Yang > Cc: "Vishal Moola (Oracle)" > Cc: Kefeng Wang > Cc: Oscar Salvador > Cc: Brendan Jackman > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Suren Baghdasaryan > Cc: Vlastimil Babka > Cc: Wei Yang > Cc: Zi Yan > Signed-off-by: Andrew Morton > --- > > mm/compaction.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/mm/compaction.c~mm-compaction-fix-low_pfn-advance-on-isolating-hu= getlb > +++ a/mm/compaction.c > @@ -989,7 +989,7 @@ isolate_migratepages_block(struct compac > * Hugepage was successfully isolated and placed > * on the cc->migratepages list. > */ > - low_pfn +=3D folio_nr_pages(folio) - 1; > + low_pfn +=3D folio_nr_pages(folio) - folio_page_idx(folio, page) -= 1; > goto isolate_success_no_list; > } > > _ Acked-by: Zi Yan -- Best Regards, Yan, Zi