thp: reduce khugepaged freezing latency

khugepaged can sometimes cause suspend to fail, requiring that the user
retry the suspend operation.

Use wait_event_freezable_timeout() instead of
schedule_timeout_interruptible() to avoid missing freezer wakeups.  A
try_to_freeze() would have been needed in the khugepaged_alloc_hugepage
tight loop too in case of the allocation failing repeatedly, and
wait_event_freezable_timeout will provide it too.

khugepaged would still freeze just fine by trying again the next minute
but it's better if it freezes immediately.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Tested-by: Jiri Slaby <jslaby@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: "Rafael J. Wysocki" <rjw@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 12 deletions

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4298abaae153..36b3d988b4ef 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2259,12 +2259,8 @@ static void khugepaged_do_scan(struct page **hpage)
 
 static void khugepaged_alloc_sleep(void)
 {
-        DEFINE_WAIT(wait);
-        add_wait_queue(&khugepaged_wait, &wait);
-        schedule_timeout_interruptible(
-                msecs_to_jiffies(
-                        khugepaged_alloc_sleep_millisecs));
-        remove_wait_queue(&khugepaged_wait, &wait);
+        wait_event_freezable_timeout(khugepaged_wait, false,
+                        msecs_to_jiffies(khugepaged_alloc_sleep_millisecs));
 }
 
 #ifndef CONFIG_NUMA
@@ -2313,14 +2309,10 @@ static void khugepaged_loop(void)
                 if (unlikely(kthread_should_stop()))
                         break;
                 if (khugepaged_has_work()) {
-                        DEFINE_WAIT(wait);
                         if (!khugepaged_scan_sleep_millisecs)
                                 continue;
-                        add_wait_queue(&khugepaged_wait, &wait);
-                        schedule_timeout_interruptible(
-                                msecs_to_jiffies(
-                                        khugepaged_scan_sleep_millisecs));
-                        remove_wait_queue(&khugepaged_wait, &wait);
+                        wait_event_freezable_timeout(khugepaged_wait, false,
+                            msecs_to_jiffies(khugepaged_scan_sleep_millisecs));
                 } else if (khugepaged_enabled())
                         wait_event_freezable(khugepaged_wait,
                                              khugepaged_wait_event());