This is a note to let you know that I've just added the patch titled
memcg: account security cred as well to kmemcg
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
memcg-account-security-cred-as-well-to-kmemcg.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 84029fd04c201a4c7e0b07ba262664900f47c6f5 Mon Sep 17 00:00:00 2001
From: Shakeel Butt <shakeelb@xxxxxxxxxx>
Date: Sat, 4 Jan 2020 12:59:43 -0800
Subject: memcg: account security cred as well to kmemcg
From: Shakeel Butt <shakeelb@xxxxxxxxxx>
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@xxxxxxxxxx
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Acked-by: Chris Down <chris@xxxxxxxxxxxxxx>
Reviewed-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);
Patches currently in stable-queue which might be from shakeelb@xxxxxxxxxx are
queue-4.19/memcg-account-security-cred-as-well-to-kmemcg.patch
