On Mon, Nov 09, 2020 at 12:33:46PM +0100, Vlastimil Babka wrote:

On 11/8/20 7:57 AM, Mike Rapoport wrote:

quoted

--- 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.

quoted

-	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.

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