[patch 133/262] mm: khugepaged: recalculate min_free_kbytes after stopping khugepaged

Andrew Morton
2021-11-05T20:41:40Z

From: Liangcai Fan <liangcaifan19@gmail.com>
Subject: 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.

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>
---

include/linux/mm.h | 1 +
mm/khugepaged.c | 10 ++++++++--
mm/page_alloc.c | 7 ++++++-
3 files changed, 15 insertions(+), 3 deletions(-)

--- a/include/linux/mm.h~mm-khugepaged-recalculate-min_free_kbytes-after-stopping-khugepaged
+++ a/include/linux/mm.h
@@ -2453,6 +2453,7 @@ extern void memmap_init_range(unsigned l
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);
--- a/mm/khugepaged.c~mm-khugepaged-recalculate-min_free_kbytes-after-stopping-khugepaged
+++ a/mm/khugepaged.c
@@ -2299,6 +2299,11 @@ static void set_recommended_min_free_kby
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_kby

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;
--- a/mm/page_alloc.c~mm-khugepaged-recalculate-min_free_kbytes-after-stopping-khugepaged
+++ a/mm/page_alloc.c
@@ -8469,7 +8469,7 @@ 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;
@@ -8483,6 +8483,11 @@ int __meminit init_per_zone_wmark_min(vo
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();
_