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SubjectRe: [PATCH] memcg: account security cred as well to kmemcg
On Thu 05-12-19 14:37:21, Shakeel Butt wrote:
> The cred_jar kmem_cache is already memcg accounted in the current
> kernel but cred->security is not. Account cred->security to kmemcg.
>
> Recently we saw high root slab usage on our production and on further
> inspection, we found a buggy application leaking processes. Though that
> buggy application was contained within its memcg but we observe much
> more system memory overhead, couple of GiBs, during that period. This
> overhead can adversely impact the isolation on the system. One of source
> of high overhead, we found was cred->secuity objects.

I am not familiar with this area much. What is the timelife of these
objects? Do they go away with a task allocating them?

> Signed-off-by: Shakeel Butt <shakeelb@google.com>
>
> ---
> kernel/cred.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/cred.c b/kernel/cred.c
> index c0a4c12d38b2..9ed51b70ed80 100644
> --- a/kernel/cred.c
> +++ b/kernel/cred.c
> @@ -223,7 +223,7 @@ struct cred *cred_alloc_blank(void)
> new->magic = CRED_MAGIC;
> #endif
>
> - if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
> + if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0)
> goto error;
>
> return new;
> @@ -282,7 +282,7 @@ struct cred *prepare_creds(void)
> new->security = NULL;
> #endif
>
> - if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
> + if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
> goto error;
> validate_creds(new);
> return new;
> @@ -715,7 +715,7 @@ struct cred *prepare_kernel_cred(struct task_struct *daemon)
> #ifdef CONFIG_SECURITY
> new->security = NULL;
> #endif
> - if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
> + if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
> goto error;
>
> put_cred(old);
> --
> 2.24.0.393.g34dc348eaf-goog
>

--
Michal Hocko
SUSE Labs

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