linux-kernel - [PATCHv2] mm: check high-order page when free it to pcp

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Date:   Tue, 20 Sep 2022 08:49:00 +0800
From:   "zhaoyang.huang" <zhaoyang.huang@...soc.com>
To:     Mel Gorman <mgorman@...hsingularity.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Zhaoyang Huang <huangzhaoyang@...il.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <ke.wang@...soc.com>
Subject: [PATCHv2] mm: check high-order page when free it to pcp

From: Zhaoyang Huang <zhaoyang.huang@...soc.com>

High-order pcp page escaped from checking when both of DEBUG_VM and debug_pagealloc
are all disabled if it allocated again from pcp_list without going to global
free list, which should be introduced by 44042b4498.

fix:44042b4498

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@...soc.com>
---
changes of v2: update comments
---
---
 mm/page_alloc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e008a3d..b54976d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1412,7 +1412,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
 
 #ifdef CONFIG_DEBUG_VM
 /*
- * With DEBUG_VM enabled, order-0 pages are checked immediately when being freed
+ * With DEBUG_VM enabled, pages are checked immediately when being freed
  * to pcp lists. With debug_pagealloc also enabled, they are also rechecked when
  * moved from pcp lists to free lists.
  */
@@ -1430,14 +1430,14 @@ static bool bulkfree_pcp_prepare(struct page *page)
 }
 #else
 /*
- * With DEBUG_VM disabled, order-0 pages being freed are checked only when
+ * With DEBUG_VM disabled, pages being freed are checked only when
  * moving from pcp lists to free list in order to reduce overhead. With
  * debug_pagealloc enabled, they are checked also immediately when being freed
  * to the pcp lists.
  */
 static bool free_pcp_prepare(struct page *page, unsigned int order)
 {
-	if (debug_pagealloc_enabled_static())
+	if (debug_pagealloc_enabled_static() || order)
 		return free_pages_prepare(page, order, true, FPI_NONE);
 	else
 		return free_pages_prepare(page, order, false, FPI_NONE);
-- 
1.9.1