1 files changed, 23 insertions, 14 deletions

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 14d6c33b0957..b12186c87f52 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -34,6 +34,7 @@
 #include <linux/random.h>
 #include <linux/rcupdate.h>
 #include <linux/sched/clock.h>
+#include <linux/sched/signal.h>
 #include <linux/rculist.h>
 #include <linux/delay.h>
 #include <trace/events/bcache.h>
@@ -734,34 +735,32 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
 
 	i = 0;
 	btree_cache_used = c->btree_cache_used;
-	list_for_each_entry_safe(b, t, &c->btree_cache_freeable, list) {
+	list_for_each_entry_safe_reverse(b, t, &c->btree_cache_freeable, list) {
 		if (nr <= 0)
 			goto out;
 
-		if (++i > 3 &&
-		    !mca_reap(b, 0, false)) {
+		if (!mca_reap(b, 0, false)) {
 			mca_data_free(b);
 			rw_unlock(true, b);
 			freed++;
 		}
 		nr--;
+		i++;
 	}
 
-	for (;  (nr--) && i < btree_cache_used; i++) {
-		if (list_empty(&c->btree_cache))
+	list_for_each_entry_safe_reverse(b, t, &c->btree_cache, list) {
+		if (nr <= 0 || i >= btree_cache_used)
 			goto out;
 
-		b = list_first_entry(&c->btree_cache, struct btree, list);
-		list_rotate_left(&c->btree_cache);
-
-		if (!b->accessed &&
-		    !mca_reap(b, 0, false)) {
+		if (!mca_reap(b, 0, false)) {
 			mca_bucket_free(b);
 			mca_data_free(b);
 			rw_unlock(true, b);
 			freed++;
-		} else
-			b->accessed = 0;
+		}
+
+		nr--;
+		i++;
 	}
 out:
 	mutex_unlock(&c->bucket_lock);
@@ -1069,7 +1068,6 @@ retry:
 	BUG_ON(!b->written);
 
 	b->parent = parent;
-	b->accessed = 1;
 
 	for (; i <= b->keys.nsets && b->keys.set[i].size; i++) {
 		prefetch(b->keys.set[i].tree);
@@ -1160,7 +1158,6 @@ retry:
 		goto retry;
 	}
 
-	b->accessed = 1;
 	b->parent = parent;
 	bch_bset_init_next(&b->keys, b->keys.set->data, bset_magic(&b->c->sb));
 
@@ -1917,6 +1914,18 @@ static int bch_gc_thread(void *arg)
 
 int bch_gc_thread_start(struct cache_set *c)
 {
+	/*
+	 * In case previous btree check operation occupies too many
+	 * system memory for bcache btree node cache, and the
+	 * registering process is selected by OOM killer. Here just
+	 * ignore the SIGKILL sent by OOM killer if there is, to
+	 * avoid kthread_run() being failed by pending signals. The
+	 * bcache registering process will exit after the registration
+	 * done.
+	 */
+	if (signal_pending(current))
+		flush_signals(current);
+
 	c->gc_thread = kthread_run(bch_gc_thread, c, "bcache_gc");
 	return PTR_ERR_OR_ZERO(c->gc_thread);
 }