thp: freeze khugepaged and ksmd
It's unclear why schedule friendly kernel threads can't be taken away by
the CPU through the scheduler itself. It's safer to stop them as they can
trigger memory allocation, if kswapd also freezes itself to avoid
generating I/O they have too.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/ksm.c b/mm/ksm.c
index 5e7d5d3..e2b0afd 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -34,6 +34,7 @@
#include <linux/swap.h>
#include <linux/ksm.h>
#include <linux/hash.h>
+#include <linux/freezer.h>
#include <asm/tlbflush.h>
#include "internal.h"
@@ -1365,7 +1366,7 @@
struct rmap_item *rmap_item;
struct page *uninitialized_var(page);
- while (scan_npages--) {
+ while (scan_npages-- && likely(!freezing(current))) {
cond_resched();
rmap_item = scan_get_next_rmap_item(&page);
if (!rmap_item)
@@ -1383,6 +1384,7 @@
static int ksm_scan_thread(void *nothing)
{
+ set_freezable();
set_user_nice(current, 5);
while (!kthread_should_stop()) {
@@ -1391,11 +1393,13 @@
ksm_do_scan(ksm_thread_pages_to_scan);
mutex_unlock(&ksm_thread_mutex);
+ try_to_freeze();
+
if (ksmd_should_run()) {
schedule_timeout_interruptible(
msecs_to_jiffies(ksm_thread_sleep_millisecs));
} else {
- wait_event_interruptible(ksm_thread_wait,
+ wait_event_freezable(ksm_thread_wait,
ksmd_should_run() || kthread_should_stop());
}
}