linux-kernel - [PATCH mm v4 3/9] memcg: enable accounting for kernfs iattrs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <647143fa-2521-10ae-2c4d-41dbb74d00cf@openvz.org>
Date:   Mon, 13 Jun 2022 08:34:59 +0300
From:   Vasily Averin <vvs@...nvz.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     kernel@...nvz.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Shakeel Butt <shakeelb@...gle.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Michal Koutný <mkoutny@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...e.com>,
        Muchun Song <songmuchun@...edance.com>, cgroups@...r.kernel.org
Subject: [PATCH mm v4 3/9] memcg: enable accounting for kernfs iattrs

kernfs nodes are quite small kernel objects, however there are few
scenarios where it consumes significant piece of all allocated memory:

1) creating a new netdevice allocates ~50Kb of memory, where ~10Kb
   was allocated for 80+ kernfs nodes.

2) cgroupv2 mkdir allocates ~60Kb of memory, ~10Kb of them are kernfs
   structures.

3) Shakeel Butt reports that Google has workloads which create 100s
   of subcontainers and they have observed high system overhead
   without memcg accounting of kernfs.

Usually new kernfs node creates few other objects:

Allocs  Alloc    Allocation
number  size
--------------------------------------------
1   +  128      (__kernfs_new_node+0x4d)        kernfs node
1   +   88      (__kernfs_iattrs+0x57)          kernfs iattrs
1   +   96      (simple_xattr_alloc+0x28)       simple_xattr, can grow over 4Kb
1       32      (simple_xattr_set+0x59)
1       8       (__kernfs_new_node+0x30)

'+' -- to be accounted

This patch enables accounting for kernfs_iattrs_cache slab cache

Signed-off-by: Vasily Averin <vvs@...nvz.org>
Reviewed-by: Roman Gushchin <roman.gushchin@...ux.dev>
Reviewed-by: Michal Koutný <mkoutny@...e.com>
Acked-by: Shakeel Butt <shakeelb@...gle.com>
Reviewed-by: Muchun Song <songmuchun@...edance.com>
---
 fs/kernfs/mount.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 3ac4191b1c40..40e896c7c86b 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -397,5 +397,6 @@ void __init kernfs_init(void)
 	/* Creates slab cache for kernfs inode attributes */
 	kernfs_iattrs_cache  = kmem_cache_create("kernfs_iattrs_cache",
 					      sizeof(struct kernfs_iattrs),
-					      0, SLAB_PANIC, NULL);
+					      0, SLAB_PANIC | SLAB_ACCOUNT,
+					      NULL);
 }
-- 
2.36.1