sched,numa: add cond_resched to task_numa_work

Normally task_numa_work scans over a fairly small amount of memory,
but it is possible to run into a large unpopulated part of virtual
memory, with no pages mapped. In that case, task_numa_work can run
for a while, and it may make sense to reschedule as required.

Cc: [email protected]
Cc: Andrea Arcangeli <[email protected]>
Signed-off-by: Rik van Riel <[email protected]>
Reported-by: Xing Gang <[email protected]>
Tested-by: Chegu Vinod <[email protected]>
Signed-off-by: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 966cc2bfcb77586d2ce9c55986aae2a3f2dce521..78157099b167c64f034c8c3348c02eaeb41c888a 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1757,6 +1757,8 @@ void task_numa_work(struct callback_head *work)
                        start = end;
                        if (pages <= 0)
                                goto out;
+
+                       cond_resched();
                } while (end != vma->vm_end);
        }