On 9/15/2020 11:27 AM, Pavel Tatashin wrote:
On Tue, Sep 15, 2020 at 12:55 AM Vijay Balakrishna
<vijayb@xxxxxxxxxxxxxxxxxxx> wrote:
set_recommended_min_free_kbytes need to honor min_free_kbytes set by the
user. Post start-of-day THP enable or memory hotplug operations can
lose user specified min_free_kbytes, in particular when it is higher than
calculated recommended value.
Signed-off-by: Vijay Balakrishna <vijayb@xxxxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
mm/khugepaged.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 4f7107476a6f..b4b753ba411a 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2253,7 +2253,7 @@ static void set_recommended_min_free_kbytes(void)
{
struct zone *zone;
int nr_zones = 0;
- unsigned long recommended_min;
+ int recommended_min;
Hi Vijay,
Please explain in log the type change. user_min_free_kbytes is of
"int" type and is initialized to -1, so comparing to unsigned leads to
undesired effect.
Hi Pasha,
I will update log. I uncovered it when trying to understand why
one-line change to address issue raised by Kirill didn't work!
for_each_populated_zone(zone) {
/*
@@ -2280,12 +2280,12 @@ static void set_recommended_min_free_kbytes(void)
/* don't ever allow to reserve more than 5% of the lowmem */
recommended_min = min(recommended_min,
- (unsigned long) nr_free_buffer_pages() / 20);
+ (int) nr_free_buffer_pages() / 20);
recommended_min <<= (PAGE_SHIFT-10);
- if (recommended_min > min_free_kbytes) {
+ if (recommended_min > user_min_free_kbytes) {
Took me a while to understand, but this change is correct. It is the
same logic that is done in init_per_zone_wmark_min().
Please join the two patches you have in one patch series.
Reviewed-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Will do.
Thanks,
Vijay
Thank you,
Pasha
