mm/page_alloc: fix min_free_kbytes calculation regarding ZONE_MOVABLE

The current calculation of min_free_kbytes only uses ZONE_DMA and
ZONE_NORMAL pages,but the ZONE_MOVABLE zone->_watermark[WMARK_MIN] will
also divide part of min_free_kbytes.This will cause the min watermark of
ZONE_NORMAL to be too small in the presence of ZONE_MOVEABLE.

__GFP_HIGH and PF_MEMALLOC allocations usually don't need movable zone
pages, so just like ZONE_HIGHMEM, cap pages_min to a small value in
__setup_per_zone_wmarks().

On my testing machine with 16GB of memory (transparent hugepage is turned
off by default, and movablecore=12G is configured) The following is a
comparative test data of watermark_min

		no patch	add patch
ZONE_DMA	1		8
ZONE_DMA32	151		709
ZONE_NORMAL	233		1113
ZONE_MOVABLE	1434		128
min_free_kbytes	7288		7326

Link: https://lkml.kernel.org/r/20230625031656.23941-1-liuq131@chinatelecom.cn
Signed-off-by: liuq <liuq131@chinatelecom.cn>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7d3460c7a480b5b1d10a9c7a68b90e333cc8fce5..fe04c4e85c42dcb352054f2e0c8d33fa9d5a0cbf 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5694,9 +5694,9 @@ static void __setup_per_zone_wmarks(void)
        struct zone *zone;
        unsigned long flags;
 
-       /* Calculate total number of !ZONE_HIGHMEM pages */
+       /* Calculate total number of !ZONE_HIGHMEM and !ZONE_MOVABLE pages */
        for_each_zone(zone) {
-               if (!is_highmem(zone))
+               if (!is_highmem(zone) && zone_idx(zone) != ZONE_MOVABLE)
                        lowmem_pages += zone_managed_pages(zone);
        }
 
@@ -5706,15 +5706,15 @@ static void __setup_per_zone_wmarks(void)
                spin_lock_irqsave(&zone->lock, flags);
                tmp = (u64)pages_min * zone_managed_pages(zone);
                do_div(tmp, lowmem_pages);
-               if (is_highmem(zone)) {
+               if (is_highmem(zone) || zone_idx(zone) == ZONE_MOVABLE) {
                        /*
                         * __GFP_HIGH and PF_MEMALLOC allocations usually don't
-                        * need highmem pages, so cap pages_min to a small
-                        * value here.
+                        * need highmem and movable zones pages, so cap pages_min
+                        * to a small  value here.
                         *
                         * The WMARK_HIGH-WMARK_LOW and (WMARK_LOW-WMARK_MIN)
                         * deltas control async page reclaim, and so should
-                        * not be capped for highmem.
+                        * not be capped for highmem and movable zones.
                         */
                        unsigned long min_pages;