From: Michal Hocko <mhocko@xxxxxxxx>
Since the page allocator can now spend CPU resource for oom_reap_mm()
for their interested OOM domains, the short sleep for waiting for the
owner of oom_lock no longer makes sense.
should_reclaim_retry() should be a natural reschedule point. PF_WQ_WORKER
is a special case which needs a stronger rescheduling policy. Doing that
unconditionally seems more straightforward than depending on a zone being
a good candidate for a further reclaim.
Thus, move the short sleep for waiting for the owner of oom_lock (which
coincidentally also serves as a guaranteed sleep for PF_WQ_WORKER threads)
to should_reclaim_retry().
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
---
mm/page_alloc.c | 40 ++++++++++++++++++----------------------
1 file changed, 18 insertions(+), 22 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4c648f7..010b536 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3904,6 +3904,7 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
{
struct zone *zone;
struct zoneref *z;
+ bool ret = false;
/*
* Costly allocations might have made a progress but this doesn't mean
@@ -3967,25 +3968,26 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
}
}
- /*
- * Memory allocation/reclaim might be called from a WQ
- * context and the current implementation of the WQ
- * concurrency control doesn't recognize that
- * a particular WQ is congested if the worker thread is
- * looping without ever sleeping. Therefore we have to
- * do a short sleep here rather than calling
- * cond_resched().
- */
- if (current->flags & PF_WQ_WORKER)
- schedule_timeout_uninterruptible(1);
- else
- cond_resched();
-
- return true;
+ ret = true;
+ goto out;
}
}
- return false;
+out:
+ /*
+ * Memory allocation/reclaim might be called from a WQ
+ * context and the current implementation of the WQ
+ * concurrency control doesn't recognize that
+ * a particular WQ is congested if the worker thread is
+ * looping without ever sleeping. Therefore we have to
+ * do a short sleep here rather than calling
+ * cond_resched().
+ */
+ if (current->flags & PF_WQ_WORKER)
+ schedule_timeout_uninterruptible(1);
+ else
+ cond_resched();
+ return ret;
}
static inline bool
@@ -4226,12 +4228,6 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
/* Retry as long as the OOM killer is making progress */
if (did_some_progress) {
no_progress_loops = 0;
- /*
- * This schedule_timeout_*() serves as a guaranteed sleep for
- * PF_WQ_WORKER threads when __zone_watermark_ok() == false.
- */
- if (!tsk_is_oom_victim(current))
- schedule_timeout_uninterruptible(1);
goto retry;
}
--
1.8.3.1
