[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>

diff --git a/mm/slab.c b/mm/slab.c
index 7137025..2317096 100644 (file)
--- 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. */