1 files changed, 228 insertions, 125 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6be8fcb..512bf9a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1457,47 +1457,171 @@ try_next_zone:
 	return page;
 }
 
-/*
- * This is the 'heart' of the zoned buddy allocator.
- */
-struct page *
-__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
-			struct zonelist *zonelist, nodemask_t *nodemask)
+static inline int
+should_alloc_retry(gfp_t gfp_mask, unsigned int order,
+				unsigned long pages_reclaimed)
 {
-	const gfp_t wait = gfp_mask & __GFP_WAIT;
-	enum zone_type high_zoneidx = gfp_zone(gfp_mask);
-	struct zoneref *z;
-	struct zone *zone;
-	struct page *page;
-	struct reclaim_state reclaim_state;
-	struct task_struct *p = current;
-	int do_retry;
-	int alloc_flags;
-	unsigned long did_some_progress;
-	unsigned long pages_reclaimed = 0;
+	/* Do not loop if specifically requested */
+	if (gfp_mask & __GFP_NORETRY)
+		return 0;
 
-	lockdep_trace_alloc(gfp_mask);
+	/*
+	 * In this implementation, order <= PAGE_ALLOC_COSTLY_ORDER
+	 * means __GFP_NOFAIL, but that may not be true in other
+	 * implementations.
+	 */
+	if (order <= PAGE_ALLOC_COSTLY_ORDER)
+		return 1;
 
-	might_sleep_if(wait);
+	/*
+	 * For order > PAGE_ALLOC_COSTLY_ORDER, if __GFP_REPEAT is
+	 * specified, then we retry until we no longer reclaim any pages
+	 * (above), or we've reclaimed an order of pages at least as
+	 * large as the allocation's order. In both cases, if the
+	 * allocation still fails, we stop retrying.
+	 */
+	if (gfp_mask & __GFP_REPEAT && pages_reclaimed < (1 << order))
+		return 1;
 
-	if (should_fail_alloc_page(gfp_mask, order))
-		return NULL;
+	/*
+	 * Don't let big-order allocations loop unless the caller
+	 * explicitly requests that.
+	 */
+	if (gfp_mask & __GFP_NOFAIL)
+		return 1;
 
-	/* the list of zones suitable for gfp_mask */
-	z = zonelist->_zonerefs;
-	if (unlikely(!z->zone)) {
-		/*
-		 * Happens if we have an empty zonelist as a result of
-		 * GFP_THISNODE being used on a memoryless node
-		 */
+	return 0;
+}
+
+static inline struct page *
+__alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
+	struct zonelist *zonelist, enum zone_type high_zoneidx,
+	nodemask_t *nodemask)
+{
+	struct page *page;
+
+	/* Acquire the OOM killer lock for the zones in zonelist */
+	if (!try_set_zone_oom(zonelist, gfp_mask)) {
+		schedule_timeout_uninterruptible(1);
 		return NULL;
 	}
 
-restart:
-	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
-			zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET);
+	/*
+	 * Go through the zonelist yet one more time, keep very high watermark
+	 * here, this is only to catch a parallel oom killing, we must fail if
+	 * we're still under heavy pressure.
+	 */
+	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask,
+		order, zonelist, high_zoneidx,
+		ALLOC_WMARK_HIGH|ALLOC_CPUSET);
 	if (page)
-		goto got_pg;
+		goto out;
+
+	/* The OOM killer will not help higher order allocs */
+	if (order > PAGE_ALLOC_COSTLY_ORDER)
+		goto out;
+
+	/* Exhausted what can be done so it's blamo time */
+	out_of_memory(zonelist, gfp_mask, order);
+
+out:
+	clear_zonelist_oom(zonelist, gfp_mask);
+	return page;
+}
+
+/* The really slow allocator path where we enter direct reclaim */
+static inline struct page *
+__alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
+	struct zonelist *zonelist, enum zone_type high_zoneidx,
+	nodemask_t *nodemask, int alloc_flags, unsigned long *did_some_progress)
+{
+	struct page *page = NULL;
+	struct reclaim_state reclaim_state;
+	struct task_struct *p = current;
+
+	cond_resched();
+
+	/* We now go into synchronous reclaim */
+	cpuset_memory_pressure_bump();
+
+	/*
+	 * The task's cpuset might have expanded its set of allowable nodes
+	 */
+	p->flags |= PF_MEMALLOC;
+	lockdep_set_current_reclaim_state(gfp_mask);
+	reclaim_state.reclaimed_slab = 0;
+	p->reclaim_state = &reclaim_state;
+
+	*did_some_progress = try_to_free_pages(zonelist, order, gfp_mask, nodemask);
+
+	p->reclaim_state = NULL;
+	lockdep_clear_current_reclaim_state();
+	p->flags &= ~PF_MEMALLOC;
+
+	cond_resched();
+
+	if (order != 0)
+		drain_all_pages();
+
+	if (likely(*did_some_progress))
+		page = get_page_from_freelist(gfp_mask, nodemask, order,
+					zonelist, high_zoneidx, alloc_flags);
+	return page;
+}
+
+static inline int
+is_allocation_high_priority(struct task_struct *p, gfp_t gfp_mask)
+{
+	if (((p->flags & PF_MEMALLOC) || unlikely(test_thread_flag(TIF_MEMDIE)))
+			&& !in_interrupt())
+		return 1;
+	return 0;
+}
+
+/*
+ * This is called in the allocator slow-path if the allocation request is of
+ * sufficient urgency to ignore watermarks and take other desperate measures
+ */
+static inline struct page *
+__alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,
+	struct zonelist *zonelist, enum zone_type high_zoneidx,
+	nodemask_t *nodemask)
+{
+	struct page *page;
+
+	do {
+		page = get_page_from_freelist(gfp_mask, nodemask, order,
+			zonelist, high_zoneidx, ALLOC_NO_WATERMARKS);
+
+		if (!page && gfp_mask & __GFP_NOFAIL)
+			congestion_wait(WRITE, HZ/50);
+	} while (!page && (gfp_mask & __GFP_NOFAIL));
+
+	return page;
+}
+
+static inline
+void wake_all_kswapd(unsigned int order, struct zonelist *zonelist,
+						enum zone_type high_zoneidx)
+{
+	struct zoneref *z;
+	struct zone *zone;
+
+	for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
+		wakeup_kswapd(zone, order);
+}
+
+static inline struct page *
+__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
+	struct zonelist *zonelist, enum zone_type high_zoneidx,
+	nodemask_t *nodemask)
+{
+	const gfp_t wait = gfp_mask & __GFP_WAIT;
+	struct page *page = NULL;
+	int alloc_flags;
+	unsigned long pages_reclaimed = 0;
+	unsigned long did_some_progress;
+	struct task_struct *p = current;
 
 	/*
 	 * GFP_THISNODE (meaning __GFP_THISNODE, __GFP_NORETRY and
@@ -1510,8 +1634,7 @@ restart:
 	if (NUMA_BUILD && (gfp_mask & GFP_THISNODE) == GFP_THISNODE)
 		goto nopage;
 
-	for_each_zone_zonelist(zone, z, zonelist, high_zoneidx)
-		wakeup_kswapd(zone, order);
+	wake_all_kswapd(order, zonelist, high_zoneidx);
 
 	/*
 	 * OK, we're below the kswapd watermark and have kicked background
@@ -1531,6 +1654,7 @@ restart:
 	if (wait)
 		alloc_flags |= ALLOC_CPUSET;
 
+restart:
 	/*
 	 * Go through the zonelist again. Let __GFP_HIGH and allocations
 	 * coming from realtime tasks go deeper into reserves.
@@ -1544,23 +1668,18 @@ restart:
 	if (page)
 		goto got_pg;
 
-	/* This allocation should allow future memory freeing. */
-
 rebalance:
-	if (((p->flags & PF_MEMALLOC) || unlikely(test_thread_flag(TIF_MEMDIE)))
-			&& !in_interrupt()) {
+	/* Allocate without watermarks if the context allows */
+	if (is_allocation_high_priority(p, gfp_mask)) {
+		/* Do not dip into emergency reserves if specified */
 		if (!(gfp_mask & __GFP_NOMEMALLOC)) {
-nofail_alloc:
-			/* go through the zonelist yet again, ignoring mins */
-			page = get_page_from_freelist(gfp_mask, nodemask, order,
-				zonelist, high_zoneidx, ALLOC_NO_WATERMARKS);
+			page = __alloc_pages_high_priority(gfp_mask, order,
+				zonelist, high_zoneidx, nodemask);
 			if (page)
 				goto got_pg;
-			if (gfp_mask & __GFP_NOFAIL) {
-				congestion_wait(WRITE, HZ/50);
-				goto nofail_alloc;
-			}
 		}
+
+		/* Ensure no recursion into the allocator */
 		goto nopage;
 	}
 
@@ -1568,93 +1687,42 @@ nofail_alloc:
 	if (!wait)
 		goto nopage;
 
-	cond_resched();
-
-	/* We now go into synchronous reclaim */
-	cpuset_memory_pressure_bump();
-
-	p->flags |= PF_MEMALLOC;
-
-	lockdep_set_current_reclaim_state(gfp_mask);
-	reclaim_state.reclaimed_slab = 0;
-	p->reclaim_state = &reclaim_state;
-
-	did_some_progress = try_to_free_pages(zonelist, order,
-						gfp_mask, nodemask);
-
-	p->reclaim_state = NULL;
-	lockdep_clear_current_reclaim_state();
-	p->flags &= ~PF_MEMALLOC;
+	/* Try direct reclaim and then allocating */
+	page = __alloc_pages_direct_reclaim(gfp_mask, order,
+					zonelist, high_zoneidx,
+					nodemask,
+					alloc_flags, &did_some_progress);
+	if (page)
+		goto got_pg;
 
-	cond_resched();
+	/*
+	 * If we failed to make any progress reclaiming, then we are
+	 * running out of options and have to consider going OOM
+	 */
+	if (!did_some_progress) {
+		if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
+			page = __alloc_pages_may_oom(gfp_mask, order,
+					zonelist, high_zoneidx,
+					nodemask);
+			if (page)
+				goto got_pg;
 
-	if (order != 0)
-		drain_all_pages();
+			/*
+			 * The OOM killer does not trigger for high-order allocations
+			 * but if no progress is being made, there are no other
+			 * options and retrying is unlikely to help
+			 */
+			if (order > PAGE_ALLOC_COSTLY_ORDER)
+				goto nopage;
 
-	if (likely(did_some_progress)) {
-		page = get_page_from_freelist(gfp_mask, nodemask, order,
-					zonelist, high_zoneidx, alloc_flags);
-		if (page)
-			goto got_pg;
-	} else if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {
-		if (!try_set_zone_oom(zonelist, gfp_mask)) {
-			schedule_timeout_uninterruptible(1);
 			goto restart;
 		}
-
-		/*
-		 * Go through the zonelist yet one more time, keep
-		 * very high watermark here, this is only to catch
-		 * a parallel oom killing, we must fail if we're still
-		 * under heavy pressure.
-		 */
-		page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask,
-			order, zonelist, high_zoneidx,
-			ALLOC_WMARK_HIGH|ALLOC_CPUSET);
-		if (page) {
-			clear_zonelist_oom(zonelist, gfp_mask);
-			goto got_pg;
-		}
-
-		/* The OOM killer will not help higher order allocs so fail */
-		if (order > PAGE_ALLOC_COSTLY_ORDER) {
-			clear_zonelist_oom(zonelist, gfp_mask);
-			goto nopage;
-		}
-
-		out_of_memory(zonelist, gfp_mask, order);
-		clear_zonelist_oom(zonelist, gfp_mask);
-		goto restart;
 	}
 
-	/*
-	 * Don't let big-order allocations loop unless the caller explicitly
-	 * requests that.  Wait for some write requests to complete then retry.
-	 *
-	 * In this implementation, order <= PAGE_ALLOC_COSTLY_ORDER
-	 * means __GFP_NOFAIL, but that may not be true in other
-	 * implementations.
-	 *
-	 * For order > PAGE_ALLOC_COSTLY_ORDER, if __GFP_REPEAT is
-	 * specified, then we retry until we no longer reclaim any pages
-	 * (above), or we've reclaimed an order of pages at least as
-	 * large as the allocation's order. In both cases, if the
-	 * allocation still fails, we stop retrying.
-	 */
+	/* Check if we should retry the allocation */
 	pages_reclaimed += did_some_progress;
-	do_retry = 0;
-	if (!(gfp_mask & __GFP_NORETRY)) {
-		if (order <= PAGE_ALLOC_COSTLY_ORDER) {
-			do_retry = 1;
-		} else {
-			if (gfp_mask & __GFP_REPEAT &&
-				pages_reclaimed < (1 << order))
-					do_retry = 1;
-		}
-		if (gfp_mask & __GFP_NOFAIL)
-			do_retry = 1;
-	}
-	if (do_retry) {
+	if (should_alloc_retry(gfp_mask, order, pages_reclaimed)) {
+		/* Wait for some write requests to complete then retry */
 		congestion_wait(WRITE, HZ/50);
 		goto rebalance;
 	}
@@ -1669,6 +1737,41 @@ nopage:
 	}
 got_pg:
 	return page;
+
+}
+
+/*
+ * This is the 'heart' of the zoned buddy allocator.
+ */
+struct page *
+__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
+			struct zonelist *zonelist, nodemask_t *nodemask)
+{
+	enum zone_type high_zoneidx = gfp_zone(gfp_mask);
+	struct page *page;
+
+	lockdep_trace_alloc(gfp_mask);
+
+	might_sleep_if(gfp_mask & __GFP_WAIT);
+
+	if (should_fail_alloc_page(gfp_mask, order))
+		return NULL;
+
+	/*
+	 * Check the zones suitable for the gfp_mask contain at least one
+	 * valid zone. It's possible to have an empty zonelist as a result
+	 * of GFP_THISNODE and a memoryless node
+	 */
+	if (unlikely(!zonelist->_zonerefs->zone))
+		return NULL;
+
+	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
+			zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET);
+	if (unlikely(!page))
+		page = __alloc_pages_slowpath(gfp_mask, order,
+				zonelist, high_zoneidx, nodemask);
+
+	return page;
 }
 EXPORT_SYMBOL(__alloc_pages_nodemask);