xarray: use kmem_cache_alloc_lru to allocate xa_node

The workingset will add the xa_node to the shadow_nodes list.  So the
allocation of xa_node should be done by kmem_cache_alloc_lru().  Using
xas_set_lru() to pass the list_lru which we want to insert xa_node into to
set up the xa_node reclaim context correctly.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Muchun Song <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Acked-by: Roman Gushchin <[email protected]>
Cc: Alex Shi <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Fam Zheng <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Kari Argillander <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Qi Zheng <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Wei Yang <[email protected]>
Cc: Xiongchun Duan <[email protected]>
Cc: Yang Shi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Muchun Song

include/linux/swap.h

@@ -334,9 +334,12 @@ void workingset_activation(struct folio *folio);
 
 /* Only track the nodes of mappings with shadow entries */
 void workingset_update_node(struct xa_node *node);
+extern struct list_lru shadow_nodes;
 #define mapping_set_update(xas, mapping) do {				\
-	if (!dax_mapping(mapping) && !shmem_mapping(mapping))		\
+	if (!dax_mapping(mapping) && !shmem_mapping(mapping)) {		\
 		xas_set_update(xas, workingset_update_node);		\
+		xas_set_lru(xas, &shadow_nodes);			\
+	}								\
 } while (0)
 
 /* linux/mm/page_alloc.c */

include/linux/xarray.h

@@ -1317,6 +1317,7 @@ struct xa_state {
 	struct xa_node *xa_node;
 	struct xa_node *xa_alloc;
 	xa_update_node_t xa_update;
+	struct list_lru *xa_lru;
 };
 
 /*
@@ -1336,7 +1337,8 @@ struct xa_state {
 	.xa_pad = 0,					\
 	.xa_node = XAS_RESTART,				\
 	.xa_alloc = NULL,				\
-	.xa_update = NULL				\
+	.xa_update = NULL,				\
+	.xa_lru = NULL,					\
 }
 
 /**
@@ -1631,6 +1633,11 @@ static inline void xas_set_update(struct xa_state *xas, xa_update_node_t update)
 	xas->xa_update = update;
 }
 
+static inline void xas_set_lru(struct xa_state *xas, struct list_lru *lru)
+{
+	xas->xa_lru = lru;
+}
+
 /**
  * xas_next_entry() - Advance iterator to next present entry.
  * @xas: XArray operation state.

lib/xarray.c

@@ -302,7 +302,7 @@ bool xas_nomem(struct xa_state *xas, gfp_t gfp)
 	}
 	if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
 		gfp |= __GFP_ACCOUNT;
-	xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+	xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
 	if (!xas->xa_alloc)
 		return false;
 	xas->xa_alloc->parent = NULL;
@@ -334,10 +334,10 @@ static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
 		gfp |= __GFP_ACCOUNT;
 	if (gfpflags_allow_blocking(gfp)) {
 		xas_unlock_type(xas, lock_type);
-		xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+		xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
 		xas_lock_type(xas, lock_type);
 	} else {
-		xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+		xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
 	}
 	if (!xas->xa_alloc)
 		return false;
@@ -371,7 +371,7 @@ static void *xas_alloc(struct xa_state *xas, unsigned int shift)
 		if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
 			gfp |= __GFP_ACCOUNT;
 
-		node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+		node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
 		if (!node) {
 			xas_set_err(xas, -ENOMEM);
 			return NULL;
@@ -1014,7 +1014,7 @@ void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
 		void *sibling = NULL;
 		struct xa_node *node;
 
-		node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
+		node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
 		if (!node)
 			goto nomem;
 		node->array = xas->xa;

mm/workingset.c

@@ -429,7 +429,7 @@ void workingset_activation(struct folio *folio)
  * point where they would still be useful.
  */
 
-static struct list_lru shadow_nodes;
+struct list_lru shadow_nodes;
 
 void workingset_update_node(struct xa_node *node)
 {