On Fri, 23 Dec 2016, Grygorii Maistrenko wrote:
> In case CONFIG_SLUB_DEBUG_ON=n find_mergeable() gets debug features
> from commandline but never checks if there are features from the
> SLAB_NEVER_MERGE set.
> As a result selected by slub_debug caches are always mergeable if they
> have been created without a custom constructor set or without one of the
> SLAB_* debug features on.
WTF is this nonsense? That check is done a few lines earlier!
struct kmem_cache *ind_mergeable(size_t size, size_t align,
unsigned long flags, const char *name, void (*ctor)(void *))
{
struct kmem_cache *s;
if (slab_nomerge || (flags & SLAB_NEVER_MERGE)) <----- !!!!!!
return NULL;
if (ctor)
return NULL;
size = ALIGN(size, sizeof(void *));
align = calculate_alignment(flags,
>
> This adds the necessary check and makes selected slab caches unmergeable
> if one of the SLAB_NEVER_MERGE features is set from commandline.
>
> Signed-off-by: Grygorii Maistrenko <grygoriimkd@xxxxxxxxx>
> ---
> mm/slab_common.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 329b03843863..7341cba8c58b 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -266,6 +266,9 @@ struct kmem_cache *find_mergeable(size_t size, size_t align,
> size = ALIGN(size, align);
> flags = kmem_cache_flags(size, flags, name, NULL);
>
> + if (flags & SLAB_NEVER_MERGE)
> + return NULL;
> +
> list_for_each_entry_reverse(s, &slab_caches, list) {
> if (slab_unmergeable(s))
> continue;
>
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