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

[Michal Hocko]

On Mon 06-02-17 06:26:41, Matthew Wilcox wrote:
> 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.

This part is not needed for the patch, strictly speaking but I wanted to
make the code more future proof.

-- 
Michal Hocko
SUSE Labs