Subject: Re: [PATCH -mmotm v2] mm: fix kmemcheck.c build errors

From: Joonsoo Kim <[email-masked]>
Date: Mon, 1 Sep 2014 09:13:13 +0900

On Sun, Aug 31, 2014 at 04:33:12PM -0700, Randy Dunlap wrote:
> On 08/31/14 07:48, Randy Dunlap wrote:
> > On 08/31/14 04:36, Andrey Ryabinin wrote:
> >> 2014-08-30 5:48 GMT+04:00 Randy Dunlap <[email-masked]>:
> >>> From: Randy Dunlap <[email-masked]>
> >>>
> >>> Add header file to fix kmemcheck.c build errors:
> >>>
> >>> ../mm/kmemcheck.c:70:7: error: dereferencing pointer to incomplete type
> >>> ../mm/kmemcheck.c:83:15: error: dereferencing pointer to incomplete type
> >>> ../mm/kmemcheck.c:95:8: error: dereferencing pointer to incomplete type
> >>> ../mm/kmemcheck.c:95:21: error: dereferencing pointer to incomplete type
> >>>
> >>> Signed-off-by: Randy Dunlap <[email-masked]>
> >>> ---
> >>>  mm/kmemcheck.c |    1 +
> >>>  1 file changed, 1 insertion(+)
> >>>
> >>> Index: mmotm-2014-0829-1515/mm/kmemcheck.c
> >>> ===================================================================
> >>> --- mmotm-2014-0829-1515.orig/mm/kmemcheck.c
> >>> +++ mmotm-2014-0829-1515/mm/kmemcheck.c
> >>> @@ -2,6 +2,7 @@
> >>>  #include <linux/mm_types.h>
> >>>  #include <linux/mm.h>
> >>>  #include <linux/slab.h>
> >>> +#include <linux/slab_def.h>
> >>
> >> This will work only for CONFIG_SLAB=y. struct kmem_cache definition
> >> was moved to internal header [*],
> >> so you need to include it here:
> >> #include "slab.h"
> >>
> >> [*] http://ozlabs.org/~akpm/mmotm/broken-out/mm-slab_common-move-kmem_cache-definition-to-internal-header.patch
> > 
> > Thanks.  That makes sense.  [testing]  mm/kmemcheck.c still has a build error:
> > 
> > In file included from ../mm/kmemcheck.c:5:0:
> > ../mm/slab.h: In function 'cache_from_obj':
> > ../mm/slab.h:283:2: error: implicit declaration of function 'memcg_kmem_enabled' [-Werror=implicit-function-declaration]
> > 
> 
> Naughty header file.  It uses something from <linux/memcontrol.h> without
> #including that header file...

Hello.

Indeed...
Thanks for catching this.

> Working patch is below.

With your patch, build also failed if CONFIG_MEMCG_KMEM=y.
Right fix is something like below.

Thanks.

--------->8----------
diff --git a/mm/kmemcheck.c b/mm/kmemcheck.c
index fd814fd..cab58bb 100644
--- a/mm/kmemcheck.c
+++ b/mm/kmemcheck.c
@@ -2,6 +2,7 @@
 #include <linux/mm_types.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
+#include "slab.h"
 #include <linux/kmemcheck.h>
 
 void kmemcheck_alloc_shadow(struct page *page, int order, gfp_t flags, int node)
diff --git a/mm/slab.h b/mm/slab.h
index 13845d0..963a3f8 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -37,6 +37,8 @@ struct kmem_cache {
 #include <linux/slub_def.h>
 #endif
 
+#include <linux/memcontrol.h>
+
 /*
  * State of the slab allocator.
  *