[Pmem] [PATCH 09/17] mm/vmscan: never demote for memcg reclaim

From: Dave Hansen <dave.hansen(a)linux.intel.com> commit 3a235693d3930e1276c8d9cc0ca5807ef292cf0a upstream Global reclaim aims to reduce the amount of memory used on a given node or set of nodes. Migrating pages to another node serves this purpose. memcg reclaim is different. Its goal is to reduce the total memory consumption of the entire memcg, across all nodes. Migration does not assist memcg reclaim because it just moves page contents between nodes rather than actually reducing memory consumption. Link: https://lkml.kernel.org/r/20210715055145.195411-9-ying.huang@intel.com Signed-off-by: Dave Hansen <dave.hansen(a)linux.intel.com> Signed-off-by: "Huang, Ying" <ying.huang(a)intel.com> Suggested-by: Yang Shi <yang.shi(a)linux.alibaba.com> Reviewed-by: Yang Shi <shy828301(a)gmail.com> Reviewed-by: Zi Yan <ziy(a)nvidia.com> Cc: Michal Hocko <mhocko(a)suse.com> Cc: Wei Xu <weixugc(a)google.com> Cc: Oscar Salvador <osalvador(a)suse.de> Cc: David Rientjes <rientjes(a)google.com> Cc: Dan Williams <dan.j.williams(a)intel.com> Cc: David Hildenbrand <david(a)redhat.com> Cc: Greg Thelen <gthelen(a)google.com> Cc: Keith Busch <kbusch(a)kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org> Signed-off-by: Baolin Wang <baolin.wang(a)linux.alibaba.com> --- mm/vmscan.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 9f854ef..5b468c9 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -299,8 +299,13 @@ static bool writeback_throttling_sane(struct scan_control *sc) static bool can_demote(int nid, struct scan_control *sc) { - if (sc && sc->no_demotion) - return false; + if (sc) { + if (sc->no_demotion) + return false; + /* It is pointless to do demotion in memcg reclaim */ + if (cgroup_reclaim(sc)) + return false; + } if (next_demotion_node(nid) == NUMA_NO_NODE) return false; -- 1.8.3.1