linux-kernel - [PATCH v2] mm/min_free_kbytes: modify min_free

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Date:   Wed, 21 Jun 2023 15:39:12 +0800
From:   liuq <liuq131@...natelecom.cn>
To:     akpm@...ux-foundation.org
Cc:     ying.huang@...el.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, liuq <liuq131@...natelecom.cn>
Subject: [PATCH v2] mm/min_free_kbytes: modify min_free_kbytes calculation rules

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 moveable
zone pages, so just like ZONE_HIGHMEM, cap pages_min to a small
value in __setup_per_zone_wmarks.

Signed-off-by: liuq <liuq131@...natelecom.cn>
---
 mm/page_alloc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 47421bedc12b..608384712a89 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6364,7 +6364,7 @@ static void __setup_per_zone_wmarks(void)
 
 	/* Calculate total number of !ZONE_HIGHMEM pages */
 	for_each_zone(zone) {
-		if (!is_highmem(zone))
+		if (!is_highmem(zone) || zone_idx(zone) != ZONE_MOVABLE)
 			lowmem_pages += zone_managed_pages(zone);
 	}
 
@@ -6374,7 +6374,7 @@ 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
-- 
2.27.0