Here are the corresponding backports to 4.19. And fix classzone_idx context differences causing patch merge conflicts.
Original commit IDS: 3334a45 mm/page_alloc: use ac->high_zoneidx for classzone_idx f27ce0e page_alloc: consider highatomic reserve in watermark fast 9282012 page_alloc: fix invalid watermark check on a negative value
Changes from v1: - Add commit information of the original patches.
Jaewon Kim (2): page_alloc: consider highatomic reserve in watermark fast page_alloc: fix invalid watermark check on a negative value
Joonsoo Kim (1): mm/page_alloc: use ac->high_zoneidx for classzone_idx
mm/internal.h | 2 +- mm/page_alloc.c | 69 +++++++++++++++++++++++++++++++++------------------------ 2 files changed, 41 insertions(+), 30 deletions(-)