[PATCH] slab: cache alloc cleanups

Clean up __cache_alloc and __cache_alloc_node functions a bit.  We no
longer need to do NUMA_BUILD tricks and the UMA allocation path is much
simpler.  No functional changes in this patch.

Note: saves few kernel text bytes on x86 NUMA build due to using gotos in
__cache_alloc_node() and moving __GFP_THISNODE check in to
fallback_alloc().

Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Acked-by: Christoph Lameter <christoph@lameter.com>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 110 insertions, 90 deletions

diff --git a/mm/slab.c b/mm/slab.c
index aea1cd25314..b595323e24a 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3189,35 +3189,6 @@ static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
         return objp;
 }
 
-static __always_inline void *__cache_alloc(struct kmem_cache *cachep,
-                                                gfp_t flags, void *caller)
-{
-        unsigned long save_flags;
-        void *objp = NULL;
-
-        cache_alloc_debugcheck_before(cachep, flags);
-
-        local_irq_save(save_flags);
-
-        if (unlikely(NUMA_BUILD &&
-                        current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY)))
-                objp = alternate_node_alloc(cachep, flags);
-
-        if (!objp)
-                objp = ____cache_alloc(cachep, flags);
-        /*
-         * We may just have run out of memory on the local node.
-         * ____cache_alloc_node() knows how to locate memory on other nodes
-         */
-        if (NUMA_BUILD && !objp)
-                objp = ____cache_alloc_node(cachep, flags, numa_node_id());
-        local_irq_restore(save_flags);
-        objp = cache_alloc_debugcheck_after(cachep, flags, objp,
-                                            caller);
-        prefetchw(objp);
-        return objp;
-}
-
 #ifdef CONFIG_NUMA
 /*
  * Try allocating on another node if PF_SPREAD_SLAB|PF_MEMPOLICY.
@@ -3249,14 +3220,20 @@ static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
  * allocator to do its reclaim / fallback magic. We then insert the
  * slab into the proper nodelist and then allocate from it.
  */
-void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
+static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
 {
-        struct zonelist *zonelist = &NODE_DATA(slab_node(current->mempolicy))
-                                        ->node_zonelists[gfp_zone(flags)];
+        struct zonelist *zonelist;
+        gfp_t local_flags;
         struct zone **z;
         void *obj = NULL;
         int nid;
-        gfp_t local_flags = (flags & GFP_LEVEL_MASK);
+
+        if (flags & __GFP_THISNODE)
+                return NULL;
+
+        zonelist = &NODE_DATA(slab_node(current->mempolicy))
+                        ->node_zonelists[gfp_zone(flags)];
+        local_flags = (flags & GFP_LEVEL_MASK);
 
 retry:
         /*
@@ -3366,16 +3343,110 @@ must_grow:
         if (x)
                 goto retry;
 
-        if (!(flags & __GFP_THISNODE))
-                /* Unable to grow the cache. Fall back to other nodes. */
-                return fallback_alloc(cachep, flags);
-
-        return NULL;
+        return fallback_alloc(cachep, flags);
 
 done:
         return obj;
 }
-#endif
+
+/**
+ * kmem_cache_alloc_node - Allocate an object on the specified node
+ * @cachep: The cache to allocate from.
+ * @flags: See kmalloc().
+ * @nodeid: node number of the target node.
+ * @caller: return address of caller, used for debug information
+ *
+ * Identical to kmem_cache_alloc but it will allocate memory on the given
+ * node, which can improve the performance for cpu bound structures.
+ *
+ * Fallback to other node is possible if __GFP_THISNODE is not set.
+ */
+static __always_inline void *
+__cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
+                   void *caller)
+{
+        unsigned long save_flags;
+        void *ptr;
+
+        cache_alloc_debugcheck_before(cachep, flags);
+        local_irq_save(save_flags);
+
+        if (unlikely(nodeid == -1))
+                nodeid = numa_node_id();
+
+        if (unlikely(!cachep->nodelists[nodeid])) {
+                /* Node not bootstrapped yet */
+                ptr = fallback_alloc(cachep, flags);
+                goto out;
+        }
+
+        if (nodeid == numa_node_id()) {
+                /*
+                 * Use the locally cached objects if possible.
+                 * However ____cache_alloc does not allow fallback
+                 * to other nodes. It may fail while we still have
+                 * objects on other nodes available.
+                 */
+                ptr = ____cache_alloc(cachep, flags);
+                if (ptr)
+                        goto out;
+        }
+        /* ___cache_alloc_node can fall back to other nodes */
+        ptr = ____cache_alloc_node(cachep, flags, nodeid);
+  out:
+        local_irq_restore(save_flags);
+        ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
+
+        return ptr;
+}
+
+static __always_inline void *
+__do_cache_alloc(struct kmem_cache *cache, gfp_t flags)
+{
+        void *objp;
+
+        if (unlikely(current->flags & (PF_SPREAD_SLAB | PF_MEMPOLICY))) {
+                objp = alternate_node_alloc(cache, flags);
+                if (objp)
+                        goto out;
+        }
+        objp = ____cache_alloc(cache, flags);
+
+        /*
+         * We may just have run out of memory on the local node.
+         * ____cache_alloc_node() knows how to locate memory on other nodes
+         */
+        if (!objp)
+                objp = ____cache_alloc_node(cache, flags, numa_node_id());
+
+  out:
+        return objp;
+}
+#else
+
+static __always_inline void *
+__do_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
+{
+        return ____cache_alloc(cachep, flags);
+}
+
+#endif /* CONFIG_NUMA */
+
+static __always_inline void *
+__cache_alloc(struct kmem_cache *cachep, gfp_t flags, void *caller)
+{
+        unsigned long save_flags;
+        void *objp;
+
+        cache_alloc_debugcheck_before(cachep, flags);
+        local_irq_save(save_flags);
+        objp = __do_cache_alloc(cachep, flags);
+        local_irq_restore(save_flags);
+        objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
+        prefetchw(objp);
+
+        return objp;
+}
 
 /*
  * Caller needs to acquire correct kmem_list's list_lock
@@ -3574,57 +3645,6 @@ out:
 }
 
 #ifdef CONFIG_NUMA
-/**
- * kmem_cache_alloc_node - Allocate an object on the specified node
- * @cachep: The cache to allocate from.
- * @flags: See kmalloc().
- * @nodeid: node number of the target node.
- * @caller: return address of caller, used for debug information
- *
- * Identical to kmem_cache_alloc but it will allocate memory on the given
- * node, which can improve the performance for cpu bound structures.
- *
- * Fallback to other node is possible if __GFP_THISNODE is not set.
- */
-static __always_inline void *
-__cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
-                int nodeid, void *caller)
-{
-        unsigned long save_flags;
-        void *ptr = NULL;
-
-        cache_alloc_debugcheck_before(cachep, flags);
-        local_irq_save(save_flags);
-
-        if (unlikely(nodeid == -1))
-                nodeid = numa_node_id();
-
-        if (likely(cachep->nodelists[nodeid])) {
-                if (nodeid == numa_node_id()) {
-                        /*
-                         * Use the locally cached objects if possible.
-                         * However ____cache_alloc does not allow fallback
-                         * to other nodes. It may fail while we still have
-                         * objects on other nodes available.
-                         */
-                        ptr = ____cache_alloc(cachep, flags);
-                }
-                if (!ptr) {
-                        /* ___cache_alloc_node can fall back to other nodes */
-                        ptr = ____cache_alloc_node(cachep, flags, nodeid);
-                }
-        } else {
-                /* Node not bootstrapped yet */
-                if (!(flags & __GFP_THISNODE))
-                        ptr = fallback_alloc(cachep, flags);
-        }
-
-        local_irq_restore(save_flags);
-        ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
-
-        return ptr;
-}
-
 void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 {
         return __cache_alloc_node(cachep, flags, nodeid,