Re: [PATCH v5 1/5] mm: introduce debug_pagealloc_{map,unmap}_pages() helpers

[Mike Rapoport <rppt@kernel.org>]

On Mon, Nov 09, 2020 at 12:33:46PM +0100, Vlastimil Babka wrote:
> On 11/8/20 7:57 AM, Mike Rapoport wrote:
> > --- a/mm/slab.c
> > +++ b/mm/slab.c
> > @@ -1428,21 +1428,19 @@ static bool is_debug_pagealloc_cache(struct kmem_cache *cachep)
> >   	return false;
> >   }
> > -#ifdef CONFIG_DEBUG_PAGEALLOC
> >   static void slab_kernel_map(struct kmem_cache *cachep, void *objp, int map)
> >   {
> >   	if (!is_debug_pagealloc_cache(cachep))
> >   		return;
> 
> Hmm, I didn't notice earlier, sorry.
> The is_debug_pagealloc_cache() above includes a
> debug_pagealloc_enabled_static() check, so it should be fine to use
> __kernel_map_pages() directly below. Otherwise we generate two static key
> checks for the same key needlessly.

Ok, I'll revert slab changes.

> > -	kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
> > +	if (map)
> > +		debug_pagealloc_map_pages(virt_to_page(objp),
> > +					  cachep->size / PAGE_SIZE);
> > +	else
> > +		debug_pagealloc_unmap_pages(virt_to_page(objp),
> > +					    cachep->size / PAGE_SIZE);
> >   }
> > -#else
> > -static inline void slab_kernel_map(struct kmem_cache *cachep, void *objp,
> > -				int map) {}
> > -
> > -#endif
> > -
> >   static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
> >   {
> >   	int size = cachep->object_size;
> > @@ -2062,7 +2060,7 @@ int __kmem_cache_create(struct kmem_cache *cachep, slab_flags_t flags)
> >   #if DEBUG
> >   	/*
> > -	 * If we're going to use the generic kernel_map_pages()
> > +	 * If we're going to use the generic debug_pagealloc_map_pages()
> >   	 * poisoning, then it's going to smash the contents of
> >   	 * the redzone and userword anyhow, so switch them off.
> >   	 */
> > 
> 

-- 
Sincerely yours,
Mike.