linux-kernel - [PATCH] page_alloc: avoid the negative free for meminfo available

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Message-Id: <20230103072807.19578-1-jaewon31.kim@samsung.com>
Date:   Tue,  3 Jan 2023 16:28:07 +0900
From:   Jaewon Kim <jaewon31.kim@...sung.com>
To:     riel@...hat.com, redkoi@...tuozzo.com, akpm@...ux-foundation.org,
        hannes@...xchg.org, mhocko@...nel.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        jaewon31.kim@...il.com, Jaewon Kim <jaewon31.kim@...sung.com>
Subject: [PATCH] page_alloc: avoid the negative free for meminfo available

The totalreserve_pages could be higher than the free because of
watermark high or watermark boost. Handle this situation and fix it to 0
free size.

Signed-off-by: Jaewon Kim <jaewon31.kim@...sung.com>
---
 mm/page_alloc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 218b28ee49ed..e510ae83d5f3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5948,6 +5948,8 @@ long si_mem_available(void)
 	 * without causing swapping or OOM.
 	 */
 	available = global_zone_page_state(NR_FREE_PAGES) - totalreserve_pages;
+	if (available < 0)
+		available = 0;
 
 	/*
 	 * Not all the page cache can be freed, otherwise the system will
-- 
2.17.1