[Cc Vlastimil] On Thu 29-10-20 16:04:35, Zi Yan wrote: > From: Zi Yan <ziy@xxxxxxxxxx> > > In isolate_migratepages_block, when cc->alloc_contig is true, we are > able to isolate compound pages, nr_migratepages and nr_isolated did not > count compound pages correctly, causing us to isolate more pages than we > thought. Use thp_nr_pages to count pages. Otherwise, we might be trapped > in too_many_isolated while loop, since the actual isolated pages can go > up to COMPACT_CLUSTER_MAX*512=16384, where COMPACT_CLUSTER_MAX is 32, > since we stop isolation after cc->nr_migratepages reaches to > COMPACT_CLUSTER_MAX. > > In addition, after we fix the issue above, cc->nr_migratepages could > never be equal to COMPACT_CLUSTER_MAX if compound pages are isolated, > thus page isolation could not stop as we intended. Change the isolation > stop condition to >=. > > Signed-off-by: Zi Yan <ziy@xxxxxxxxxx> > --- > mm/compaction.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index ee1f8439369e..0683a4999581 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1012,8 +1012,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > > isolate_success: > list_add(&page->lru, &cc->migratepages); > - cc->nr_migratepages++; > - nr_isolated++; > + cc->nr_migratepages += thp_nr_pages(page); > + nr_isolated += thp_nr_pages(page); Does thp_nr_pages work for __PageMovable pages? -- Michal Hocko SUSE Labs
