1 files changed, 45 insertions, 38 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 48550c66f1f..b7ed3767564 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2207,9 +2207,12 @@ static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)
  * Throttle direct reclaimers if backing storage is backed by the network
  * and the PFMEMALLOC reserve for the preferred node is getting dangerously
  * depleted. kswapd will continue to make progress and wake the processes
- * when the low watermark is reached
+ * when the low watermark is reached.
+ *
+ * Returns true if a fatal signal was delivered during throttling. If this
+ * happens, the page allocator should not consider triggering the OOM killer.
  */
-static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
+static bool throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
                                         nodemask_t *nodemask)
 {
         struct zone *zone;
@@ -2224,13 +2227,20 @@ static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
          * processes to block on log_wait_commit().
          */
         if (current->flags & PF_KTHREAD)
-                return;
+                goto out;
+
+        /*
+         * If a fatal signal is pending, this process should not throttle.
+         * It should return quickly so it can exit and free its memory
+         */
+        if (fatal_signal_pending(current))
+                goto out;
 
         /* Check if the pfmemalloc reserves are ok */
         first_zones_zonelist(zonelist, high_zoneidx, NULL, &zone);
         pgdat = zone->zone_pgdat;
         if (pfmemalloc_watermark_ok(pgdat))
-                return;
+                goto out;
 
         /* Account for the throttling */
         count_vm_event(PGSCAN_DIRECT_THROTTLE);
@@ -2246,12 +2256,20 @@ static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist,
         if (!(gfp_mask & __GFP_FS)) {
                 wait_event_interruptible_timeout(pgdat->pfmemalloc_wait,
                         pfmemalloc_watermark_ok(pgdat), HZ);
-                return;
+
+                goto check_pending;
         }
 
         /* Throttle until kswapd wakes the process */
         wait_event_killable(zone->zone_pgdat->pfmemalloc_wait,
                 pfmemalloc_watermark_ok(pgdat));
+
+check_pending:
+        if (fatal_signal_pending(current))
+                return true;
+
+out:
+        return false;
 }
 
 unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
@@ -2273,13 +2291,12 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
                 .gfp_mask = sc.gfp_mask,
         };
 
-        throttle_direct_reclaim(gfp_mask, zonelist, nodemask);
-
         /*
-         * Do not enter reclaim if fatal signal is pending. 1 is returned so
-         * that the page allocator does not consider triggering OOM
+         * Do not enter reclaim if fatal signal was delivered while throttled.
+         * 1 is returned so that the page allocator does not OOM kill at this
+         * point.
          */
-        if (fatal_signal_pending(current))
+        if (throttle_direct_reclaim(gfp_mask, zonelist, nodemask))
                 return 1;
 
         trace_mm_vmscan_direct_reclaim_begin(order,
@@ -2397,6 +2414,19 @@ static void age_active_anon(struct zone *zone, struct scan_control *sc)
         } while (memcg);
 }
 
+static bool zone_balanced(struct zone *zone, int order,
+                          unsigned long balance_gap, int classzone_idx)
+{
+        if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone) +
+                                    balance_gap, classzone_idx, 0))
+                return false;
+
+        if (COMPACTION_BUILD && order && !compaction_suitable(zone, order))
+                return false;
+
+        return true;
+}
+
 /*
  * pgdat_balanced is used when checking if a node is balanced for high-order
  * allocations. Only zones that meet watermarks and are in a zone allowed
@@ -2475,8 +2505,7 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
                         continue;
                 }
 
-                if (!zone_watermark_ok_safe(zone, order, high_wmark_pages(zone),
-                                                        i, 0))
+                if (!zone_balanced(zone, order, 0, i))
                         all_zones_ok = false;
                 else
                         balanced += zone->present_pages;
@@ -2585,8 +2614,7 @@ loop_again:
                                 break;
                         }
 
-                        if (!zone_watermark_ok_safe(zone, order,
-                                        high_wmark_pages(zone), 0, 0)) {
+                        if (!zone_balanced(zone, order, 0, 0)) {
                                 end_zone = i;
                                 break;
                         } else {
@@ -2662,9 +2690,8 @@ loop_again:
                                 testorder = 0;
 
                         if ((buffer_heads_over_limit && is_highmem_idx(i)) ||
-                                    !zone_watermark_ok_safe(zone, testorder,
-                                        high_wmark_pages(zone) + balance_gap,
-                                        end_zone, 0)) {
+                            !zone_balanced(zone, testorder,
+                                           balance_gap, end_zone)) {
                                 shrink_zone(zone, &sc);
 
                                 reclaim_state->reclaimed_slab = 0;
@@ -2691,8 +2718,7 @@ loop_again:
                                 continue;
                         }
 
-                        if (!zone_watermark_ok_safe(zone, testorder,
-                                        high_wmark_pages(zone), end_zone, 0)) {
+                        if (!zone_balanced(zone, testorder, 0, end_zone)) {
                                 all_zones_ok = 0;
                                 /*
                                  * We are still under min water mark.  This
@@ -2797,29 +2823,10 @@ out:
                         if (!populated_zone(zone))
                                 continue;
 
-                        if (zone->all_unreclaimable &&
-                            sc.priority != DEF_PRIORITY)
-                                continue;
-
-                        /* Would compaction fail due to lack of free memory? */
-                        if (COMPACTION_BUILD &&
-                            compaction_suitable(zone, order) == COMPACT_SKIPPED)
-                                goto loop_again;
-
-                        /* Confirm the zone is balanced for order-0 */
-                        if (!zone_watermark_ok(zone, 0,
-                                        high_wmark_pages(zone), 0, 0)) {
-                                order = sc.order = 0;
-                                goto loop_again;
-                        }
-
                         /* Check if the memory needs to be defragmented. */
                         if (zone_watermark_ok(zone, order,
                                     low_wmark_pages(zone), *classzone_idx, 0))
                                 zones_need_compaction = 0;
-
-                        /* If balanced, clear the congested flag */
-                        zone_clear_flag(zone, ZONE_CONGESTED);
                 }
 
                 if (zones_need_compaction)