Subject: Re: linux-next: build failure after merge of the akpm tree

From: Thierry Reding <[email-masked]>
Date: Thu, 6 Nov 2014 12:24:00 +0100

On Thu, Nov 06, 2014 at 07:36:18PM +1100, Stephen Rothwell wrote:
> Hi Andrew,
> 
> After merging the akpm tree, today's linux-next build (sparc defconfig)
> failed like this:
> 
> mm/slab.c: In function 'slab_alloc':
> mm/slab.c:3260:4: error: implicit declaration of function 'slab_free' [-Werror=implicit-function-declaration]
>     slab_free(cachep, objp);
>     ^
> mm/slab.c: At top level:
> mm/slab.c:3534:29: warning: conflicting types for 'slab_free'
>  static __always_inline void slab_free(struct kmem_cache *cachep, void *objp)
>                              ^
> mm/slab.c:3534:29: error: static declaration of 'slab_free' follows non-static declaration
> mm/slab.c:3260:4: note: previous implicit declaration of 'slab_free' was here
>     slab_free(cachep, objp);
>     ^
> 
> I am not sure what caused this, but it is something in the akpm-current
> or akpm trees (possibly interacting with something else).

I fixed this using the attached patch.

Thierry
From a9ec6cfacb892e044a5f76dce3b7fc9a3337d01a Mon Sep 17 00:00:00 2001
From: Thierry Reding <[email-masked]>
Date: Thu, 6 Nov 2014 11:59:23 +0100
Subject: [PATCH] mm/slab: Always predeclare slab_free()

Commit 5da1c3c725ab ("slab: recharge slab pages to the allocating memory
cgroup") added a predeclaration of the new slab_free() helper so that it
can be used in slab_alloc_node() and slab_alloc(). However the prototype
is added in an #ifdef CONFIG_NUMA protected section of code, which works
fine for slab_alloc_node() but fails for slab_alloc().

Fixes the following build warnings and errors:

	mm/slab.c: In function 'slab_alloc':
	mm/slab.c:3260:4: error: implicit declaration of function 'slab_free' [-Werror=implicit-function-declaration]
	    slab_free(cachep, objp);
	    ^
	mm/slab.c: At top level:
	mm/slab.c:3534:29: warning: conflicting types for 'slab_free'
	 static __always_inline void slab_free(struct kmem_cache *cachep, void *objp)
				     ^
	mm/slab.c:3534:29: error: static declaration of 'slab_free' follows non-static declaration
	mm/slab.c:3260:4: note: previous implicit declaration of 'slab_free' was here
	    slab_free(cachep, objp);
	    ^

Reported-by: Stephen Rothwell <[email-masked]>
Signed-off-by: Thierry Reding <[email-masked]>
---
 mm/slab.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 61b01c2ae1d9..00cd028404cb 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2961,6 +2961,8 @@ out:
 	return objp;
 }
 
+static __always_inline void slab_free(struct kmem_cache *cachep, void *objp);
+
 #ifdef CONFIG_NUMA
 /*
  * Try allocating on another node if PFA_SPREAD_SLAB is a mempolicy is set.
@@ -3133,8 +3135,6 @@ done:
 	return obj;
 }
 
-static __always_inline void slab_free(struct kmem_cache *cachep, void *objp);
-
 static __always_inline void *
 slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
 		   unsigned long caller)
-- 
2.1.3