[PATCH 11/16] sched: Check current->mm before allocating NUMA faults

Mel Gorman
2013-07-11T09:49:03Z

task_numa_placement checks current->mm but after buffers for faults
have already been uselessly allocated. Move the check earlier.

[peterz@infradead.org: Identified the problem]
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
kernel/sched/fair.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0d4e516..54702c9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -834,8 +834,6 @@ static void task_numa_placement(struct task_struct *p)
int seq, nid, max_nid = 0;
unsigned long max_faults = 0;

- if (!p->mm) /* for example, ksmd faulting in a user's mm */
- return;
seq = ACCESS_ONCE(p->mm->numa_scan_seq);
if (p->numa_scan_seq == seq)
return;
@@ -912,6 +910,10 @@ void task_numa_fault(int last_nid, int node, int pages, bool migrated)
if (!sched_feat_numa(NUMA))
return;

+ /* for example, ksmd faulting in a user's mm */
+ if (!p->mm)
+ return;
+
/* For now, do not attempt to detect private/shared accesses */
priv = 1;

--
1.8.1.4