mm: kvmalloc: align kvrealloc() with krealloc()

Besides the obvious (and desired) difference between krealloc() and
kvrealloc(), there is some inconsistency in their function signatures
and behavior:

 - krealloc() frees the memory when the requested size is zero, whereas
   kvrealloc() simply returns a pointer to the existing allocation.

 - krealloc() is self-contained, whereas kvrealloc() relies on the caller
   to provide the size of the previous allocation.

Inconsistent behavior throughout allocation APIs is error prone, hence make
kvrealloc() behave like krealloc(), which seems superior in all mentioned
aspects.

Besides that, implementing kvrealloc() by making use of krealloc() and
vrealloc() provides oppertunities to grow (and shrink) allocations more
efficiently. For instance, vrealloc() can be optimized to allocate and
map additional pages to grow the allocation or unmap and free unused
pages to shrink the allocation.

Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/slab.h b/include/linux/slab.h
index eb2bf4629157..c9cb42203183 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -841,8 +841,8 @@ kvmalloc_array_node_noprof(size_t n, size_t size, gfp_t flags, int node)
 #define kvcalloc_node(...)			alloc_hooks(kvcalloc_node_noprof(__VA_ARGS__))
 #define kvcalloc(...)				alloc_hooks(kvcalloc_noprof(__VA_ARGS__))
 
-extern void *kvrealloc_noprof(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
-		      __realloc_size(3);
+void *kvrealloc_noprof(const void *p, size_t size, gfp_t flags)
+		__realloc_size(2);
 #define kvrealloc(...)				alloc_hooks(kvrealloc_noprof(__VA_ARGS__))
 
 extern void kvfree(const void *addr);