patches/mm-workingset-do-not-protect-workingset_shadow_nodes.patch

From ad867acb5f23f05b8eea1bf89ce7e42f6e9bf8d1 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 29 Jan 2015 17:19:44 +0100
Subject: [PATCH] mm/workingset: Do not protect workingset_shadow_nodes with
 irq off

workingset_shadow_nodes is protected by local_irq_disable(). Some users
use spin_lock_irq().
Replace the irq/on with a local_lock(). Rename workingset_shadow_nodes
so I catch users of it which will be introduced later.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

diff --git a/include/linux/swap.h b/include/linux/swap.h
index ba5882419a7d..bcdefa817ed5 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -11,6 +11,7 @@
 #include <linux/fs.h>
 #include <linux/atomic.h>
 #include <linux/page-flags.h>
+#include <linux/locallock.h>
 #include <asm/page.h>
 
 struct notifier_block;
@@ -254,7 +255,8 @@ struct swap_info_struct {
 void *workingset_eviction(struct address_space *mapping, struct page *page);
 bool workingset_refault(void *shadow);
 void workingset_activation(struct page *page);
-void workingset_update_node(struct radix_tree_node *node, void *private);
+void __workingset_update_node(struct radix_tree_node *node, void *private);
+DECLARE_LOCAL_IRQ_LOCK(shadow_nodes_lock);
 
 /* linux/mm/page_alloc.c */
 extern unsigned long totalram_pages;
diff --git a/mm/filemap.c b/mm/filemap.c
index 681da61080bc..3d9cd0e58578 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -110,6 +110,7 @@
  * ->i_mmap_rwsem
  *   ->tasklist_lock            (memory_failure, collect_procs_ao)
  */
+DECLARE_LOCAL_IRQ_LOCK(shadow_nodes_lock);
 
 static int page_cache_tree_insert(struct address_space *mapping,
 				  struct page *page, void **shadowp)
@@ -142,8 +143,10 @@ static int page_cache_tree_insert(struct address_space *mapping,
 						      true);
 		}
 	}
+	local_lock(shadow_nodes_lock);
 	__radix_tree_replace(&mapping->page_tree, node, slot, page,
-			     workingset_update_node, mapping);
+			     __workingset_update_node, mapping);
+	local_unlock(shadow_nodes_lock);
 	mapping->nrpages++;
 	return 0;
 }
@@ -160,6 +163,7 @@ static void page_cache_tree_delete(struct address_space *mapping,
 	VM_BUG_ON_PAGE(PageTail(page), page);
 	VM_BUG_ON_PAGE(nr != 1 && shadow, page);
 
+	local_lock(shadow_nodes_lock);
 	for (i = 0; i < nr; i++) {
 		struct radix_tree_node *node;
 		void **slot;
@@ -171,8 +175,9 @@ static void page_cache_tree_delete(struct address_space *mapping,
 
 		radix_tree_clear_tags(&mapping->page_tree, node, slot);
 		__radix_tree_replace(&mapping->page_tree, node, slot, shadow,
-				     workingset_update_node, mapping);
+				     __workingset_update_node, mapping);
 	}
+	local_unlock(shadow_nodes_lock);
 
 	if (shadow) {
 		mapping->nrexceptional += nr;
diff --git a/mm/truncate.c b/mm/truncate.c
index 83a059e8cd1d..47ef312bbbee 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -41,8 +41,10 @@ static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
 		goto unlock;
 	if (*slot != entry)
 		goto unlock;
+	local_lock(shadow_nodes_lock);
 	__radix_tree_replace(&mapping->page_tree, node, slot, NULL,
-			     workingset_update_node, mapping);
+			     __workingset_update_node, mapping);
+	local_unlock(shadow_nodes_lock);
 	mapping->nrexceptional--;
 unlock:
 	spin_unlock_irq(&mapping->tree_lock);
diff --git a/mm/workingset.c b/mm/workingset.c
index b8c9ab678479..5fa253835c59 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -339,9 +339,10 @@ void workingset_activation(struct page *page)
  * point where they would still be useful.
  */
 
-static struct list_lru shadow_nodes;
+static struct list_lru __shadow_nodes;
+DEFINE_LOCAL_IRQ_LOCK(shadow_nodes_lock);
 
-void workingset_update_node(struct radix_tree_node *node, void *private)
+void __workingset_update_node(struct radix_tree_node *node, void *private)
 {
 	struct address_space *mapping = private;
 
@@ -359,10 +360,10 @@ void workingset_update_node(struct radix_tree_node *node, void *private)
 	 */
 	if (node->count && node->count == node->exceptional) {
 		if (list_empty(&node->private_list))
-			list_lru_add(&shadow_nodes, &node->private_list);
+			list_lru_add(&__shadow_nodes, &node->private_list);
 	} else {
 		if (!list_empty(&node->private_list))
-			list_lru_del(&shadow_nodes, &node->private_list);
+			list_lru_del(&__shadow_nodes, &node->private_list);
 	}
 }
 
@@ -374,9 +375,9 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 	unsigned long cache;
 
 	/* list_lru lock nests inside IRQ-safe mapping->tree_lock */
-	local_irq_disable();
-	nodes = list_lru_shrink_count(&shadow_nodes, sc);
-	local_irq_enable();
+	local_lock_irq(shadow_nodes_lock);
+	nodes = list_lru_shrink_count(&__shadow_nodes, sc);
+	local_unlock_irq(shadow_nodes_lock);
 
 	/*
 	 * Approximate a reasonable limit for the radix tree nodes
@@ -477,15 +478,15 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
 	inc_node_state(page_pgdat(virt_to_page(node)), WORKINGSET_NODERECLAIM);
 	inc_memcg_page_state(virt_to_page(node), WORKINGSET_NODERECLAIM);
 	__radix_tree_delete_node(&mapping->page_tree, node,
-				 workingset_update_node, mapping);
+				 __workingset_update_node, mapping);
 
 out_invalid:
 	spin_unlock(&mapping->tree_lock);
 	ret = LRU_REMOVED_RETRY;
 out:
-	local_irq_enable();
+	local_unlock_irq(shadow_nodes_lock);
 	cond_resched();
-	local_irq_disable();
+	local_lock_irq(shadow_nodes_lock);
 	spin_lock(lru_lock);
 	return ret;
 }
@@ -496,9 +497,9 @@ static unsigned long scan_shadow_nodes(struct shrinker *shrinker,
 	unsigned long ret;
 
 	/* list_lru lock nests inside IRQ-safe mapping->tree_lock */
-	local_irq_disable();
-	ret = list_lru_shrink_walk(&shadow_nodes, sc, shadow_lru_isolate, NULL);
-	local_irq_enable();
+	local_lock_irq(shadow_nodes_lock);
+	ret = list_lru_shrink_walk(&__shadow_nodes, sc, shadow_lru_isolate, NULL);
+	local_unlock_irq(shadow_nodes_lock);
 	return ret;
 }
 
@@ -536,7 +537,7 @@ static int __init workingset_init(void)
 	pr_info("workingset: timestamp_bits=%d max_order=%d bucket_order=%u\n",
 	       timestamp_bits, max_order, bucket_order);
 
-	ret = __list_lru_init(&shadow_nodes, true, &shadow_nodes_key);
+	ret = __list_lru_init(&__shadow_nodes, true, &shadow_nodes_key);
 	if (ret)
 		goto err;
 	ret = register_shrinker(&workingset_shadow_shrinker);
@@ -544,7 +545,7 @@ static int __init workingset_init(void)
 		goto err_list_lru;
 	return 0;
 err_list_lru:
-	list_lru_destroy(&shadow_nodes);
+	list_lru_destroy(&__shadow_nodes);
 err:
 	return ret;
 }
-- 
2.1.4