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    Subject[PATCH 1/4] slqb: Do not use DEFINE_PER_CPU for per-node data
    Date
    SLQB uses DEFINE_PER_CPU to define per-node areas. An implicit
    assumption is made that all valid node IDs will have matching valid CPU
    ids. In memoryless configurations, it is possible to have a node ID with
    no CPU having the same ID. When this happens, per-cpu areas are not
    initialised and the per-node data is effectively random.

    An attempt was made to force the allocation of per-cpu areas corresponding
    to active node IDs. However, for reasons unknown this led to silent
    lockups. Instead, this patch fixes the SLQB problem by forcing the per-node
    data to be statically declared.

    Signed-off-by: Mel Gorman <mel@csn.ul.ie>
    ---
    mm/slqb.c | 16 ++++++++--------
    1 files changed, 8 insertions(+), 8 deletions(-)

    diff --git a/mm/slqb.c b/mm/slqb.c
    index 4ca85e2..4d72be2 100644
    --- a/mm/slqb.c
    +++ b/mm/slqb.c
    @@ -1944,16 +1944,16 @@ static void init_kmem_cache_node(struct kmem_cache *s,
    static DEFINE_PER_CPU(struct kmem_cache_cpu, kmem_cache_cpus);
    #endif
    #ifdef CONFIG_NUMA
    -/* XXX: really need a DEFINE_PER_NODE for per-node data, but this is better than
    - * a static array */
    -static DEFINE_PER_CPU(struct kmem_cache_node, kmem_cache_nodes);
    +/* XXX: really need a DEFINE_PER_NODE for per-node data because a static
    + * array is wasteful */
    +static struct kmem_cache_node kmem_cache_nodes[MAX_NUMNODES];
    #endif

    #ifdef CONFIG_SMP
    static struct kmem_cache kmem_cpu_cache;
    static DEFINE_PER_CPU(struct kmem_cache_cpu, kmem_cpu_cpus);
    #ifdef CONFIG_NUMA
    -static DEFINE_PER_CPU(struct kmem_cache_node, kmem_cpu_nodes); /* XXX per-nid */
    +static struct kmem_cache_node kmem_cpu_nodes[MAX_NUMNODES]; /* XXX per-nid */
    #endif
    #endif

    @@ -1962,7 +1962,7 @@ static struct kmem_cache kmem_node_cache;
    #ifdef CONFIG_SMP
    static DEFINE_PER_CPU(struct kmem_cache_cpu, kmem_node_cpus);
    #endif
    -static DEFINE_PER_CPU(struct kmem_cache_node, kmem_node_nodes); /*XXX per-nid */
    +static struct kmem_cache_node kmem_node_nodes[MAX_NUMNODES]; /*XXX per-nid */
    #endif

    #ifdef CONFIG_SMP
    @@ -2918,15 +2918,15 @@ void __init kmem_cache_init(void)
    for_each_node_state(i, N_NORMAL_MEMORY) {
    struct kmem_cache_node *n;

    - n = &per_cpu(kmem_cache_nodes, i);
    + n = &kmem_cache_nodes[i];
    init_kmem_cache_node(&kmem_cache_cache, n);
    kmem_cache_cache.node_slab[i] = n;
    #ifdef CONFIG_SMP
    - n = &per_cpu(kmem_cpu_nodes, i);
    + n = &kmem_cpu_nodes[i];
    init_kmem_cache_node(&kmem_cpu_cache, n);
    kmem_cpu_cache.node_slab[i] = n;
    #endif
    - n = &per_cpu(kmem_node_nodes, i);
    + n = &kmem_node_nodes[i];
    init_kmem_cache_node(&kmem_node_cache, n);
    kmem_node_cache.node_slab[i] = n;
    }
    --
    1.6.3.3


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