On Fri, Sep 05, 2014 at 01:01:02PM -0700, Andrew Morton wrote:

On Fri,  5 Sep 2014 16:28:06 +0900 Joonsoo Kim [off-list ref] wrote:

quoted

mm-slab_common-move-kmem_cache-definition-to-internal-header.patch
in mmotm makes following build failure.

../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

../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]

Add header files to fix kmemcheck.c build errors.

[iamjoonsoo.kim@lge.com] move up memcontrol.h header
to fix build failure if CONFIG_MEMCG_KMEM=y too.

Looking at this line

quoted

Signed-off-by: Randy Dunlap <redacted>

and at this line

quoted

Signed-off-by: Joonsoo Kim <redacted>

I am suspecting that this patch was authored by Randy.  But there was
no From: line at start-of-changelog to communicate this?

quoted

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.
  *

It seems a bit wrong to include a fairly high-level memcontol.h into a
fairly low-level slab.h, but I expect it will work.

I can't really see how
mm-slab_common-move-kmem_cache-definition-to-internal-header.patch
caused the breakage.  I don't know how you were triggering this build
failure - please always include such info in the changelogs.

Hello,

Sorry for all mistakes.
Here goes new one having proper commit description and authorship.

------------>8------------------

From d2026b2cf932ae459fb421a66923288352993e74 Mon Sep 17 00:00:00 2001

From: Randy Dunlap <redacted>
Date: Fri, 5 Sep 2014 16:18:13 +0900
Subject: [PATCH] mm/slab: fix kmemcheck.c build errors

If we turn on CONFIG_KMEMCHECK,
mm-slab_common-move-kmem_cache-definition-to-internal-header.patch
in mmotm makes following build failure.

../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

Reason for this failure is that kmemcheck uses internal fields of struct
kmem_cache and above patch moves these struct kmem_cache definitions to
mm/slab.h, so kmemcheck which only includes include/linux/slab.h can't
dereference them.

Add header file mm/slab.h in kmemcheck.c to fix kmemcheck.c build errors.

There is one more problem revealing from this change.
mm/slab.h uses memcg's internal fields so it needs memcontrol.h. Util now,
only sl[aou]b use mm/slab.h header, and they luckilly include memcontrol.h
through swap.h so no problems happen. Unfortunately, kmemcheck doesn't
include memcontrol.h so problem happens if we add mm/slab.h in kmemcheck.c.
To fix it too, add memcontrol.h into mm/slab.h.

[iamjoonsoo.kim@lge.com] add commit description and move up memcontrol.h
header to fix build failure if CONFIG_MEMCG_KMEM=y too.
Signed-off-by: Randy Dunlap <redacted>
Signed-off-by: Joonsoo Kim <redacted>
---
 mm/kmemcheck.c |    1 +
 mm/slab.h      |    2 ++
 2 files changed, 3 insertions(+)

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.
  *

-- 
1.7.9.5

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