linux-kernel - [PATCH] mm: khugepaged: Recalculate min_free

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Message-Id: <1633937809-16558-1-git-send-email-liangcaifan19@gmail.com>
Date:   Mon, 11 Oct 2021 15:36:49 +0800
From:   Liangcai Fan <liangcaifan19@...il.com>
To:     liangcai.fan@...soc.com, akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Liangcai Fan <liangcaifan19@...il.com>,
        Chunyan Zhang <zhang.lyra@...il.com>
Subject: [PATCH] mm: khugepaged: Recalculate min_free_kbytes after stopping khugepaged

When initializing transparent huge pages, min_free_kbytes would be
calculated according to what khugepaged expected.
So when disable transparent huge pages, min_free_kbytes should be
recalculated instead of the higher value set by khugepaged.

Signed-off-by: Liangcai Fan <liangcaifan19@...il.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@...il.com>
---
 include/linux/mm.h |  1 +
 mm/khugepaged.c    | 10 ++++++++--
 mm/page_alloc.c    |  7 ++++++-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 73a52ab..4ef07e8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2475,6 +2475,7 @@ extern void memmap_init_range(unsigned long, int, unsigned long,
 		unsigned long, unsigned long, enum meminit_context,
 		struct vmem_altmap *, int migratetype);
 extern void setup_per_zone_wmarks(void);
+extern void calculate_min_free_kbytes(void);
 extern int __meminit init_per_zone_wmark_min(void);
 extern void mem_init(void);
 extern void __init mmap_init(void);
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 045cc57..682130f 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2291,6 +2291,11 @@ static void set_recommended_min_free_kbytes(void)
 	int nr_zones = 0;
 	unsigned long recommended_min;
 
+	if (!khugepaged_enabled()) {
+		calculate_min_free_kbytes();
+		goto update_wmarks;
+	}
+
 	for_each_populated_zone(zone) {
 		/*
 		 * We don't need to worry about fragmentation of
@@ -2326,6 +2331,8 @@ static void set_recommended_min_free_kbytes(void)
 
 		min_free_kbytes = recommended_min;
 	}
+
+update_wmarks:
 	setup_per_zone_wmarks();
 }
 
@@ -2347,12 +2354,11 @@ int start_stop_khugepaged(void)
 
 		if (!list_empty(&khugepaged_scan.mm_head))
 			wake_up_interruptible(&khugepaged_wait);
-
-		set_recommended_min_free_kbytes();
 	} else if (khugepaged_thread) {
 		kthread_stop(khugepaged_thread);
 		khugepaged_thread = NULL;
 	}
+	set_recommended_min_free_kbytes();
 fail:
 	mutex_unlock(&khugepaged_mutex);
 	return err;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b37435c..1d44386 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8452,7 +8452,7 @@ void setup_per_zone_wmarks(void)
  * 8192MB:	11584k
  * 16384MB:	16384k
  */
-int __meminit init_per_zone_wmark_min(void)
+void calculate_min_free_kbytes(void)
 {
 	unsigned long lowmem_kbytes;
 	int new_min_free_kbytes;
@@ -8470,6 +8470,11 @@ int __meminit init_per_zone_wmark_min(void)
 		pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n",
 				new_min_free_kbytes, user_min_free_kbytes);
 	}
+}
+
+int __meminit init_per_zone_wmark_min(void)
+{
+	calculate_min_free_kbytes();
 	setup_per_zone_wmarks();
 	refresh_zone_stat_thresholds();
 	setup_per_zone_lowmem_reserve();
-- 
1.9.1