linux-kernel - [PATCH 1/1] kasan: fix livelock in qlist_move

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Date:   Tue, 28 Nov 2017 04:04:02 +0000
From:   zhouzhouyi@...il.com
To:     aryabinin@...tuozzo.com, glider@...gle.com, dvyukov@...gle.com,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Zhouyi Zhou <zhouzhouyi@...il.com>
Subject: [PATCH 1/1] kasan: fix livelock in qlist_move_cache

From: Zhouyi Zhou <zhouzhouyi@...il.com>

This patch fix livelock by conditionally release cpu to let others
has a chance to run.

Tested on x86_64.
Signed-off-by: Zhouyi Zhou <zhouzhouyi@...il.com>
---
 mm/kasan/quarantine.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/mm/kasan/quarantine.c b/mm/kasan/quarantine.c
index 3a8ddf8..33eeff4 100644
--- a/mm/kasan/quarantine.c
+++ b/mm/kasan/quarantine.c
@@ -265,10 +265,13 @@ static void qlist_move_cache(struct qlist_head *from,
 				   struct kmem_cache *cache)
 {
 	struct qlist_node *curr;
+	struct qlist_head tmp_head;
+	unsigned long flags;
 
 	if (unlikely(qlist_empty(from)))
 		return;
 
+	qlist_init(&tmp_head);
 	curr = from->head;
 	qlist_init(from);
 	while (curr) {
@@ -278,10 +281,17 @@ static void qlist_move_cache(struct qlist_head *from,
 		if (obj_cache == cache)
 			qlist_put(to, curr, obj_cache->size);
 		else
-			qlist_put(from, curr, obj_cache->size);
+			qlist_put(&tmp_head, curr, obj_cache->size);
 
 		curr = next;
+
+		if (need_resched()) {
+			spin_unlock_irqrestore(&quarantine_lock, flags);
+			cond_resched();
+			spin_lock_irqsave(&quarantine_lock, flags);
+		}
 	}
+	qlist_move_all(&tmp_head, from);
 }
 
 static void per_cpu_remove_cache(void *arg)
-- 
2.1.4