tun: only queue packets on device

[~andy/linux] / mm / vmscan.c

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 48550c66f1f21d4fdff9afd38f6c1fa97f56ef49..cbf84e152f043c82b15d754a9f8c2c4c50866488 100644 (file)
--- 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,