commit bd3400ea173fb611cdf2030d03620185ff6c0b0e
author Liangcai Fan <liangcaifan19@gmail.com> Fri Nov 05 13:41:36 2021 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> Sat Nov 06 13:30:39 2021 -0700
tree 06641ec051ba94a768253dcc282bb0531b665217
parent 8531fc6f52f5fc201f43d8c36c2606e25748b1c4

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 transparent huge pages get disabled, min_free_kbytes should be
recalculated instead of the higher value set by khugepaged.

Link: https://lkml.kernel.org/r/1633937809-16558-1-git-send-email-liangcaifan19@gmail.com
Signed-off-by: Liangcai Fan <liangcaifan19@gmail.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/khugepaged.c

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 8a8b3aa..6299619 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2299,6 +2299,11 @@ 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
@@ -2334,6 +2339,8 @@ static void set_recommended_min_free_kbytes(void)
 
 		min_free_kbytes = recommended_min;
 	}
+
+update_wmarks:
 	setup_per_zone_wmarks();
 }
 
@@ -2355,12 +2362,11 @@ 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;