[PATCH] NUMA slab locking fixes: move color_next to l3

colour_next is used as an index to add a colouring offset to a new slab in the
cache (colour_off * colour_next).  Now with the NUMA aware slab allocator, it
makes sense to colour slabs added on the same node sequentially with
colour_next.

This patch moves the colouring index "colour_next" per-node by placing it on
kmem_list3 rather than kmem_cache.

This also helps simplify locking for CPU up and down paths.

Signed-off-by: Alok N Kataria <alokk@calsoftinc.com>
Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 11 deletions

diff --git a/mm/slab.c b/mm/slab.c
index 71370256a7eb..2317096166dd 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -294,6 +294,7 @@ struct kmem_list3 {
         unsigned long next_reap;
         int free_touched;
         unsigned int free_limit;
+        unsigned int colour_next;       /* Per-node cache coloring */
         spinlock_t list_lock;
         struct array_cache *shared;     /* shared per node */
         struct array_cache **alien;     /* on other nodes */
@@ -344,6 +345,7 @@ static void kmem_list3_init(struct kmem_list3 *parent)
         INIT_LIST_HEAD(&parent->slabs_free);
         parent->shared = NULL;
         parent->alien = NULL;
+        parent->colour_next = 0;
         spin_lock_init(&parent->list_lock);
         parent->free_objects = 0;
         parent->free_touched = 0;
@@ -390,7 +392,6 @@ struct kmem_cache {
 
         size_t colour;          /* cache colouring range */
         unsigned int colour_off;        /* colour offset */
-        unsigned int colour_next;       /* cache colouring */
         struct kmem_cache *slabp_cache;
         unsigned int slab_size;
         unsigned int dflags;    /* dynamic flags */
@@ -1119,7 +1120,6 @@ void __init kmem_cache_init(void)
                 BUG();
 
         cache_cache.colour = left_over / cache_cache.colour_off;
-        cache_cache.colour_next = 0;
         cache_cache.slab_size = ALIGN(cache_cache.num * sizeof(kmem_bufctl_t) +
                                       sizeof(struct slab), cache_line_size());
 
@@ -2324,18 +2324,19 @@ static int cache_grow(struct kmem_cache *cachep, gfp_t flags, int nodeid)
                  */
                 ctor_flags |= SLAB_CTOR_ATOMIC;
 
-        /* About to mess with non-constant members - lock. */
+        /* Take the l3 list lock to change the colour_next on this node */
         check_irq_off();
-        spin_lock(&cachep->spinlock);
+        l3 = cachep->nodelists[nodeid];
+        spin_lock(&l3->list_lock);
 
         /* Get colour for the slab, and cal the next value. */
-        offset = cachep->colour_next;
-        cachep->colour_next++;
-        if (cachep->colour_next >= cachep->colour)
-                cachep->colour_next = 0;
-        offset *= cachep->colour_off;
+        offset = l3->colour_next;
+        l3->colour_next++;
+        if (l3->colour_next >= cachep->colour)
+                l3->colour_next = 0;
+        spin_unlock(&l3->list_lock);
 
-        spin_unlock(&cachep->spinlock);
+        offset *= cachep->colour_off;
 
         check_irq_off();
         if (local_flags & __GFP_WAIT)
@@ -2367,7 +2368,6 @@ static int cache_grow(struct kmem_cache *cachep, gfp_t flags, int nodeid)
         if (local_flags & __GFP_WAIT)
                 local_irq_disable();
         check_irq_off();
-        l3 = cachep->nodelists[nodeid];
         spin_lock(&l3->list_lock);
 
         /* Make slab active. */