From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 29 Jan 2015 17:19:44 +0100
Subject: mm/workingset: Do not protect workingset_shadow_nodes with irq off
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
Git-commit: a08096a6716603d9bc90e972782cdaf749a77a32
Patch-mainline: Queued in subsystem maintainer repository
References: SLE Realtime Extension

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>
Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
---
 include/linux/swap.h |    8 +++++---
 mm/filemap.c         |   12 +++++++++---
 mm/truncate.c        |    4 +++-
 mm/workingset.c      |   31 ++++++++++++++++---------------
 4 files changed, 33 insertions(+), 22 deletions(-)

--- 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;
@@ -256,12 +257,13 @@ bool workingset_refault(void *shadow);
 void workingset_activation(struct page *page);
 
 /* Do not use directly, use workingset_lookup_update */
-void workingset_update_node(struct radix_tree_node *node);
+void __workingset_update_node(struct radix_tree_node *node);
+DECLARE_LOCAL_IRQ_LOCK(shadow_nodes_lock);
 
 /* Returns workingset_update_node() if the mapping has shadow entries. */
-#define workingset_lookup_update(mapping)				\
+#define __workingset_lookup_update(mapping)				\
 ({									\
-	radix_tree_update_node_t __helper = workingset_update_node;	\
+	radix_tree_update_node_t __helper = __workingset_update_node;	\
 	if (dax_mapping(mapping) || shmem_mapping(mapping))		\
 		__helper = NULL;					\
 	__helper;							\
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -134,8 +134,10 @@ static int page_cache_tree_insert(struct
 		if (shadowp)
 			*shadowp = p;
 	}
+	local_lock(shadow_nodes_lock);
 	__radix_tree_replace(&mapping->page_tree, node, slot, page,
-			     workingset_lookup_update(mapping));
+			     __workingset_lookup_update(mapping));
+	local_unlock(shadow_nodes_lock);
 	mapping->nrpages++;
 	return 0;
 }
@@ -152,6 +154,7 @@ static void page_cache_tree_delete(struc
 	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;
@@ -163,8 +166,9 @@ static void page_cache_tree_delete(struc
 
 		radix_tree_clear_tags(&mapping->page_tree, node, slot);
 		__radix_tree_replace(&mapping->page_tree, node, slot, shadow,
-				workingset_lookup_update(mapping));
+				__workingset_lookup_update(mapping));
 	}
+	local_unlock(shadow_nodes_lock);
 
 	page->mapping = NULL;
 	/* Leave page->index set: truncation lookup relies upon it */
@@ -358,9 +362,11 @@ page_cache_tree_delete_batch(struct addr
 		} else {
 			tail_pages--;
 		}
+		local_lock(shadow_nodes_lock);
 		radix_tree_clear_tags(&mapping->page_tree, iter.node, slot);
 		__radix_tree_replace(&mapping->page_tree, iter.node, slot, NULL,
-				workingset_lookup_update(mapping));
+				__workingset_lookup_update(mapping));
+		local_unlock(shadow_nodes_lock);
 		total_pages++;
 	}
 	mapping->nrpages -= total_pages;
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -40,8 +40,10 @@ static inline void __clear_shadow_entry(
 		return;
 	if (*slot != entry)
 		return;
+	local_lock(shadow_nodes_lock);
 	__radix_tree_replace(&mapping->page_tree, node, slot, NULL,
-			     workingset_update_node);
+			     __workingset_update_node);
+	local_unlock(shadow_nodes_lock);
 	mapping->nrexceptional--;
 }
 
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -339,9 +339,10 @@ void workingset_activation(struct 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 __workingset_update_node(struct radix_tree_node *node)
 {
 	/*
 	 * Track non-empty nodes that contain only shadow entries;
@@ -353,10 +354,10 @@ void workingset_update_node(struct radix
 	 */
 	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);
 	}
 }
 
@@ -368,9 +369,9 @@ static unsigned long count_shadow_nodes(
 	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
@@ -471,15 +472,15 @@ static enum lru_status shadow_lru_isolat
 	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_lookup_update(mapping));
+				 __workingset_lookup_update(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;
 }
@@ -490,9 +491,9 @@ static unsigned long scan_shadow_nodes(s
 	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;
 }
 
@@ -530,7 +531,7 @@ 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);
@@ -538,7 +539,7 @@ 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;
 }