linux-kernel - [PATCH -next v3 1/2] mm: Cap zone movable's min wmark to small value

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Date:   Mon, 5 Sep 2022 11:28:57 +0800
From:   Wupeng Ma <mawupeng1@...wei.com>
To:     <akpm@...ux-foundation.org>, <david@...hat.com>, <npiggin@...e.de>,
        <ying.huang@...el.com>, <hannes@...xchg.org>
CC:     <corbet@....net>, <mcgrof@...nel.org>, <mgorman@...e.de>,
        <keescook@...omium.org>, <yzaikin@...gle.com>,
        <songmuchun@...edance.com>, <mike.kravetz@...cle.com>,
        <osalvador@...e.de>, <surenb@...gle.com>, <mawupeng1@...wei.com>,
        <rppt@...nel.org>, <charante@...eaurora.org>, <jsavitz@...hat.com>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>
Subject: [PATCH -next v3 1/2] mm: Cap zone movable's min wmark to small value

From: Ma Wupeng <mawupeng1@...wei.com>

Since min_free_kbytes is based on gfp_zone(GFP_USER) which does not include
zone movable. However zone movable will get its min share in
__setup_per_zone_wmarks() which does not make any sense.

And like highmem pages, __GFP_HIGH and PF_MEMALLOC allocations usually
don't need movable pages, so there is no need to assign min pages for zone
movable.

Let's cap pages_min for zone movable to a small value here just link
highmem pages.

Signed-off-by: Ma Wupeng <mawupeng1@...wei.com>
---
 mm/page_alloc.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e5486d47406e..f1e4474879f1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8636,9 +8636,9 @@ static void __setup_per_zone_wmarks(void)
 	struct zone *zone;
 	unsigned long flags;
 
-	/* Calculate total number of !ZONE_HIGHMEM pages */
+	/* Calculate total number of none highmem/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);
 	}
 
@@ -8648,15 +8648,15 @@ 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/movable 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/movable zone.
 			 */
 			unsigned long min_pages;
 
-- 
2.25.1