mm: catch memory commitment underflow

[deliverable/linux.git] / mm / page_alloc.c

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8bcfe3ae20cb85c7dd1e02a69a489e71d382521f..c1c6cb78e5cae282d37fe69054698b633e98ccee 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1257,15 +1257,11 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
 void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
 {
        unsigned long flags;
-       int to_drain;
-       unsigned long batch;
+       int to_drain, batch;
 
        local_irq_save(flags);
        batch = ACCESS_ONCE(pcp->batch);
-       if (pcp->count >= batch)
-               to_drain = batch;
-       else
-               to_drain = pcp->count;
+       to_drain = min(pcp->count, batch);
        if (to_drain > 0) {
                free_pcppages_bulk(zone, to_drain, pcp);
                pcp->count -= to_drain;
@@ -2447,7 +2443,7 @@ static inline int
 gfp_to_alloc_flags(gfp_t gfp_mask)
 {
        int alloc_flags = ALLOC_WMARK_MIN | ALLOC_CPUSET;
-       const gfp_t wait = gfp_mask & __GFP_WAIT;
+       const bool atomic = !(gfp_mask & (__GFP_WAIT | __GFP_NO_KSWAPD));
 
        /* __GFP_HIGH is assumed to be the same as ALLOC_HIGH to save a branch. */
        BUILD_BUG_ON(__GFP_HIGH != (__force gfp_t) ALLOC_HIGH);
@@ -2456,20 +2452,20 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
         * The caller may dip into page reserves a bit more if the caller
         * cannot run direct reclaim, or if the caller has realtime scheduling
         * policy or is asking for __GFP_HIGH memory.  GFP_ATOMIC requests will
-        * set both ALLOC_HARDER (!wait) and ALLOC_HIGH (__GFP_HIGH).
+        * set both ALLOC_HARDER (atomic == true) and ALLOC_HIGH (__GFP_HIGH).
         */
        alloc_flags |= (__force int) (gfp_mask & __GFP_HIGH);
 
-       if (!wait) {
+       if (atomic) {
                /*
-                * Not worth trying to allocate harder for
-                * __GFP_NOMEMALLOC even if it can't schedule.
+                * Not worth trying to allocate harder for __GFP_NOMEMALLOC even
+                * if it can't schedule.
                 */
-               if  (!(gfp_mask & __GFP_NOMEMALLOC))
+               if (!(gfp_mask & __GFP_NOMEMALLOC))
                        alloc_flags |= ALLOC_HARDER;
                /*
-                * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.
-                * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
+                * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the
+                * comment for __cpuset_node_allowed_softwall().
                 */
                alloc_flags &= ~ALLOC_CPUSET;
        } else if (unlikely(rt_task(current)) && !in_interrupt())
@@ -2962,7 +2958,7 @@ EXPORT_SYMBOL(alloc_pages_exact);
  * Note this is not alloc_pages_exact_node() which allocates on a specific node,
  * but is not exact.
  */
-void *alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
+void * __meminit alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
 {
        unsigned order = get_order(size);
        struct page *p = alloc_pages_node(nid, gfp_mask, order);
@@ -2970,7 +2966,6 @@ void *alloc_pages_exact_nid(int nid, size_t size, gfp_t gfp_mask)
                return NULL;
        return make_alloc_exact((unsigned long)page_address(p), order, size);
 }
-EXPORT_SYMBOL(alloc_pages_exact_nid);
 
 /**
  * free_pages_exact - release memory allocated via alloc_pages_exact()