X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=mm%2Fvmscan.c;h=febbc044e792c427264c908dfe1303ca87ea9c0b;hb=7080d306762f5e4a1418aec4f496af7f879c94c4;hp=2f7c6ae8fae07c23c0e539ef97f756448943920e;hpb=acf92b485cccf028177f46918e045c0c4e80ee10;p=karo-tx-linux.git

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2f7c6ae8fae0..febbc044e792 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -253,6 +253,8 @@ unsigned long shrink_slab(struct shrink_control *shrink,
 		int shrink_ret = 0;
 		long nr;
 		long new_nr;
+		long batch_size = shrinker->batch ? shrinker->batch
+						  : SHRINK_BATCH;
 
 		/*
 		 * copy the current shrinker scan count into a local variable
@@ -276,6 +278,21 @@ unsigned long shrink_slab(struct shrink_control *shrink,
 			total_scan = max_pass;
 		}
 
+		/*
+		 * We need to avoid excessive windup on filesystem shrinkers
+		 * due to large numbers of GFP_NOFS allocations causing the
+		 * shrinkers to return -1 all the time. This results in a large
+		 * nr being built up so when a shrink that can do some work
+		 * comes along it empties the entire cache due to nr >>>
+		 * max_pass.  This is bad for sustaining a working set in
+		 * memory.
+		 *
+		 * Hence only allow the shrinker to scan the entire cache when
+		 * a large delta change is calculated directly.
+		 */
+		if (delta < max_pass / 4)
+			total_scan = min(total_scan, max_pass / 2);
+
 		/*
 		 * Avoid risking looping forever due to too large nr value:
 		 * never try to free more than twice the estimate number of
@@ -288,19 +305,18 @@ unsigned long shrink_slab(struct shrink_control *shrink,
 					nr_pages_scanned, lru_pages,
 					max_pass, delta, total_scan);
 
-		while (total_scan >= SHRINK_BATCH) {
-			long this_scan = SHRINK_BATCH;
+		while (total_scan >= batch_size) {
 			int nr_before;
 
 			nr_before = do_shrinker_shrink(shrinker, shrink, 0);
 			shrink_ret = do_shrinker_shrink(shrinker, shrink,
-							this_scan);
+							batch_size);
 			if (shrink_ret == -1)
 				break;
 			if (shrink_ret < nr_before)
 				ret += nr_before - shrink_ret;
-			count_vm_events(SLABS_SCANNED, this_scan);
-			total_scan -= this_scan;
+			count_vm_events(SLABS_SCANNED, batch_size);
+			total_scan -= batch_size;
 
 			cond_resched();
 		}