mm: khugepaged: recalculate min_free_kbytes after memory hotplug as expected by khugepaged
When memory is hotplug added or removed the min_free_kbytes should be
recalculated based on what is expected by khugepaged. Currently after
hotplug, min_free_kbytes will be set to a lower default and higher
default set when THP enabled is lost.
This change restores min_free_kbytes as expected for THP consumers.
[vijayb@linux.microsoft.com: v5]
Link: https://lkml.kernel.org/r/1601398153-5517-1-git-send-email-vijayb@linux.microsoft.com
Fixes: f000565adb77 ("thp: set recommended min free kbytes")
Signed-off-by: Vijay Balakrishna <vijayb@linux.microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Allen Pais <apais@microsoft.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/1600305709-2319-2-git-send-email-vijayb@linux.microsoft.com
Link: https://lkml.kernel.org/r/1600204258-13683-1-git-send-email-vijayb@linux.microsoft.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 3a494cf..58b0d9c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -56,6 +56,9 @@ enum scan_result {
#define CREATE_TRACE_POINTS
#include <trace/events/huge_memory.h>
+static struct task_struct *khugepaged_thread __read_mostly;
+static DEFINE_MUTEX(khugepaged_mutex);
+
/* default scan 8*512 pte (or vmas) every 30 second */
static unsigned int khugepaged_pages_to_scan __read_mostly;
static unsigned int khugepaged_pages_collapsed;
@@ -2304,8 +2307,6 @@ static void set_recommended_min_free_kbytes(void)
int start_stop_khugepaged(void)
{
- static struct task_struct *khugepaged_thread __read_mostly;
- static DEFINE_MUTEX(khugepaged_mutex);
int err = 0;
mutex_lock(&khugepaged_mutex);
@@ -2332,3 +2333,11 @@ int start_stop_khugepaged(void)
mutex_unlock(&khugepaged_mutex);
return err;
}
+
+void khugepaged_min_free_kbytes_update(void)
+{
+ mutex_lock(&khugepaged_mutex);
+ if (khugepaged_enabled() && khugepaged_thread)
+ set_recommended_min_free_kbytes();
+ mutex_unlock(&khugepaged_mutex);
+}
