Re: [PATCH v2 06/13] slab: Add kmem_cache_gfp_flags() helper function.

On 03/14/2012 03:21 AM, Suleiman Souhlal wrote:

On Sun, Mar 11, 2012 at 3:53 AM, Glauber Costa[off-list ref]  wrote:

quoted

On 03/10/2012 12:39 AM, Suleiman Souhlal wrote:

quoted

This function returns the gfp flags that are always applied to
allocations of a kmem_cache.

Signed-off-by: Suleiman Souhlal<redacted>
---
  include/linux/slab_def.h |    6 ++++++
  include/linux/slob_def.h |    6 ++++++
  include/linux/slub_def.h |    6 ++++++
  3 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index fbd1117..25f9a6a 100644
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h

@@ -159,6 +159,12 @@ found:
        return __kmalloc(size, flags);
  }

+static inline gfp_t
+kmem_cache_gfp_flags(struct kmem_cache *cachep)
+{
+       return cachep->gfpflags;
+}
+
  #ifdef CONFIG_NUMA
  extern void *__kmalloc_node(size_t size, gfp_t flags, int node);
  extern void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int

node);

diff --git a/include/linux/slob_def.h b/include/linux/slob_def.h
index 0ec00b3..3fa527d 100644
--- a/include/linux/slob_def.h
+++ b/include/linux/slob_def.h

@@ -34,4 +34,10 @@ static __always_inline void *__kmalloc(size_t size,

gfp_t flags)
        return kmalloc(size, flags);
  }

+static inline gfp_t
+kmem_cache_gfp_flags(struct kmem_cache *cachep)
+{
+       return 0;
+}
+
  #endif /* __LINUX_SLOB_DEF_H */

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index a32bcfd..5911d81 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h

@@ -313,4 +313,10 @@ static __always_inline void *kmalloc_node(size_t

size, gfp_t flags, int node)
  }
  #endif

+static inline gfp_t
+kmem_cache_gfp_flags(struct kmem_cache *cachep)
+{
+       return cachep->allocflags;
+}
+

Why is this needed? Can't the caller just call
mem_cgroup_get_kmem_cache(cachep, flags | cachep->allocflags) ?

Because slub calls this cachep->allocflags, while slab calls it
cachep->gfpflags.

So what?
That function is only called from slab.c anyway. Let slab call it
mem_cgroup_get_kmem_cache(cachep, flags | cachep->allocflags);
and slub
mem_cgroup_get_kmem_cache(cachep, flags | cachep->gfpflags);

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