On Fri 18-04-14 13:08:17, Andrew Morton wrote:
[...]
> From: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
> Subject: slub: fix memcg_propagate_slab_attrs
>
> After creating a cache for a memcg we should initialize its sysfs attrs
> with the values from its parent. That's what memcg_propagate_slab_attrs
> is for. Currently it's broken - we clearly muddled root-vs-memcg caches
> there. Let's fix it up.
Andrew didn't so I'll do. What is the effect of the mismatch? I am
really drowning in that code...
> Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
> Cc: Christoph Lameter <cl@xxxxxxxxx>
> Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> mm/slub.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff -puN mm/slub.c~slub-fix-memcg_propagate_slab_attrs mm/slub.c
> --- a/mm/slub.c~slub-fix-memcg_propagate_slab_attrs
> +++ a/mm/slub.c
> @@ -5071,15 +5071,18 @@ static void memcg_propagate_slab_attrs(s
> #ifdef CONFIG_MEMCG_KMEM
> int i;
> char *buffer = NULL;
> + struct kmem_cache *root_cache;
>
> - if (!is_root_cache(s))
> + if (is_root_cache(s))
> return;
>
> + root_cache = s->memcg_params->root_cache;
> +
> /*
> * This mean this cache had no attribute written. Therefore, no point
> * in copying default values around
> */
> - if (!s->max_attr_size)
> + if (!root_cache->max_attr_size)
> return;
>
> for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) {
> @@ -5101,7 +5104,7 @@ static void memcg_propagate_slab_attrs(s
> */
> if (buffer)
> buf = buffer;
> - else if (s->max_attr_size < ARRAY_SIZE(mbuf))
> + else if (root_cache->max_attr_size < ARRAY_SIZE(mbuf))
> buf = mbuf;
> else {
> buffer = (char *) get_zeroed_page(GFP_KERNEL);
> @@ -5110,7 +5113,7 @@ static void memcg_propagate_slab_attrs(s
> buf = buffer;
> }
>
> - attr->show(s->memcg_params->root_cache, buf);
> + attr->show(root_cache, buf);
> attr->store(s, buf, strlen(buf));
> }
>
> _
>
> Patches currently in -mm which might be from vdavydov@xxxxxxxxxxxxx are
>
> slub-fix-memcg_propagate_slab_attrs.patch
> slb-charge-slabs-to-kmemcg-explicitly.patch
> mm-get-rid-of-__gfp_kmemcg.patch
> mm-get-rid-of-__gfp_kmemcg-fix.patch
> slab-document-kmalloc_order.patch
>
--
Michal Hocko
SUSE Labs
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