On Wed, 29 Sept 2021 at 14:42, Marco Elver [off-list ref] wrote:

On Wed, Sep 29, 2021 at 07:49PM -0400, yanjun.zhu@linux.dev wrote:

quoted

From: Zhu Yanjun <redacted>

Since the function __kasan_kmalloc is only used in kasan module,
remove EXPORT_SYMBOL to this function.

This is incorrect, see below.

quoted

@@ -521,7 +521,6 @@ void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object
 {
      return ____kasan_kmalloc(cache, object, size, flags);
 }
-EXPORT_SYMBOL(__kasan_kmalloc);

Sorry, but this will break all users of kmalloc() with KASAN on if
!TRACING:

*module users.

An allmodconfig but with CONFIG_TRACING=n will probably show you the problem.

        __always_inline kmalloc() include/linux/slab.h
         -> __always_inline kmem_cache_alloc_trace() include/linux/slab.h
          -> __always_inline kasan_kmalloc() include/linux/kasan.h
           -> __kasan_kmalloc() mm/kasan/common.c