memcg: account security cred as well to kmemcg

commit 84029fd04c201a4c7e0b07ba262664900f47c6f5 upstream.

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 source of high overhead we found was cred->security objects, which
have a lifetime of at least the life of the process which allocated
them.

Link: http://lkml.kernel.org/r/20191205223721.40034-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/cred.c b/kernel/cred.c
index 5ab1f7ec946e13a5848ced77d0ecec559ea4d53e..a9f0f8b21d8c8f9df0a09ad3b511572601b5ecb9 100644 (file)
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -220,7 +220,7 @@ 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;
@@ -279,7 +279,7 @@ 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;
@@ -654,7 +654,7 @@ 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);