From: Shakeel Butt shakeelb@google.com
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
--- kernel/cred.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- 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 #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);