Re: [PATCH v3 07/19] mm: memcg/slab: allocate obj_cgroups for non-root slab pages

[Roman Gushchin]

On Wed, Apr 22, 2020 at 01:46:56PM -0700, Roman Gushchin wrote:
> Allocate and release memory to store obj_cgroup pointers for each
> non-root slab page. Reuse page->mem_cgroup pointer to store a pointer
> to the allocated space.
> 
> To distinguish between obj_cgroups and memcg pointers in case
> when it's not obvious which one is used (as in page_cgroup_ino()),
> let's always set the lowest bit in the obj_cgroup case.
> 
> Signed-off-by: Roman Gushchin <guro@xxxxxx>
> ---
>  include/linux/mm_types.h |  5 ++++-
>  include/linux/slab_def.h |  5 +++++
>  include/linux/slub_def.h |  2 ++
>  mm/memcontrol.c          | 17 +++++++++++---
>  mm/slab.c                |  3 ++-
>  mm/slab.h                | 48 ++++++++++++++++++++++++++++++++++++++++
>  mm/slub.c                |  5 +++++
>  7 files changed, 80 insertions(+), 5 deletions(-)
>
...
> diff --git a/mm/slub.c b/mm/slub.c
> index 8d16babe1829..68c2c45dfac1 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -5992,4 +5992,9 @@ ssize_t slabinfo_write(struct file *file, const char __user *buffer,
>  {
>  	return -EIO;
>  }
> +
> +int objs_per_slab(struct kmem_cache *cache)
> +{
> +	return oo_objects(cache->oo);
> +}
>  #endif /* CONFIG_SLUB_DEBUG */
> -- 
> 2.25.3
> 


Ooops, the build bot found that objs_per_slab() was accidentally guarded by
CONFIG_SLUB_DEBUG. An updated version below.

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