Re: [PATCH 1/6] lockdep: allow to disable reclaim lockup detection

[Matthew Wilcox]

On Mon, Feb 06, 2017 at 03:07:13PM +0100, Michal Hocko wrote:
> While we are at it also make sure that the radix tree doesn't
> accidentaly override tags stored in the upper part of the gfp_mask.

> diff --git a/lib/radix-tree.c b/lib/radix-tree.c
> index 9dc093d5ef39..7550be09f9d6 100644
> --- a/lib/radix-tree.c
> +++ b/lib/radix-tree.c
> @@ -2274,6 +2274,8 @@ static int radix_tree_cpu_dead(unsigned int cpu)
>  void __init radix_tree_init(void)
>  {
>  	int ret;
> +
> +	BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
>  	radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
>  			sizeof(struct radix_tree_node), 0,
>  			SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,

That's going to have a conceptual conflict with some patches I have
in flight.  I'll take this part through my radix tree patch collection.