On Fri 06-12-19 08:51:21, Shakeel Butt wrote: > On Fri, Dec 6, 2019 at 12:17 AM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > 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? > > > > Lifetime is at least the life of the process allocating them. Thanks for the clarification! It is better to be explicit about this in the changelog I believe because it would make a review much easier. Accounting for objects which are not bound to a user process context is more complex and requires much more considerations. > > > Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx> With that clarification Acked-by: Michal Hocko <mhocko@xxxxxxxx> > > > > > > --- > > > 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 -- Michal Hocko SUSE Labs
