mm/slab: delete cache_alloc_debugcheck_before()

It only does a might_sleep_if(GFP_RECLAIM) check, which is already covered
by the might_alloc() in slab_pre_alloc_hook().  And all callers of
cache_alloc_debugcheck_before() call that beforehand already.

Link: https://lkml.kernel.org/r/20220605152539.3196045-2-daniel.vetter@ffwll.ch
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/slab.c

@@ -2958,12 +2958,6 @@ direct_grow:
 	return ac->entry[--ac->avail];
 }
 
-static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep,
-						gfp_t flags)
-{
-	might_sleep_if(gfpflags_allow_blocking(flags));
-}
-
 #if DEBUG
 static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
 				gfp_t flags, void *objp, unsigned long caller)
@@ -3205,7 +3199,6 @@ slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, size_t orig_
 	if (unlikely(ptr))
 		goto out_hooks;
 
-	cache_alloc_debugcheck_before(cachep, flags);
 	local_irq_save(save_flags);
 
 	if (nodeid == NUMA_NO_NODE)
@@ -3290,7 +3283,6 @@ slab_alloc(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags,
 	if (unlikely(objp))
 		goto out;
 
-	cache_alloc_debugcheck_before(cachep, flags);
 	local_irq_save(save_flags);
 	objp = __do_cache_alloc(cachep, flags);
 	local_irq_restore(save_flags);
@@ -3527,8 +3519,6 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
 	if (!s)
 		return 0;
 
-	cache_alloc_debugcheck_before(s, flags);
-
 	local_irq_disable();
 	for (i = 0; i < size; i++) {
 		void *objp = kfence_alloc(s, s->object_size, flags) ?: __do_cache_alloc(s, flags);