From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Subject: mm/migrate: clear __GFP_RECLAIM to make the migration callback consistent with regular THP allocations new_page_nodemask is a migration callback and it tries to use a common gfp flags for the target page allocation whether it is a base page or a THP. The later only adds GFP_TRANSHUGE to the given mask. This results in the allocation being slightly more aggressive than necessary because the resulting gfp mask will contain also __GFP_RECLAIM_KSWAPD. THP allocations usually exclude this flag to reduce over eager background reclaim during a high THP allocation load which has been seen during large mmaps initialization. There is no indication that this is a problem for migration as well but theoretically the same might happen when migrating large mappings to a different node. Make the migration callback consistent with regular THP allocations. [akpm@xxxxxxxxxxxxxxxxxxxx: fix comment typo, per Vlastimil] Link: http://lkml.kernel.org/r/1594622517-20681-5-git-send-email-iamjoonsoo.kim@xxxxxxx Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: Vlastimil Babka <vbabka@xxxxxxx> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/migrate.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/mm/migrate.c~mm-migrate-clear-__gfp_reclaim-to-make-the-migration-callback-consistent-with-regular-thp-allocations +++ a/mm/migrate.c @@ -1554,6 +1554,11 @@ struct page *new_page_nodemask(struct pa } if (PageTransHuge(page)) { + /* + * clear __GFP_RECLAIM to make the migration callback + * consistent with regular THP allocations. + */ + gfp_mask &= ~__GFP_RECLAIM; gfp_mask |= GFP_TRANSHUGE; order = HPAGE_PMD_ORDER; } _
