linux-kernel - Re: [PATCH 4/4] selftests: memcg: Remove protection from top level memcg

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: <20220513191459.qgnmnu62xgxvhx5z@dev0025.ash9.facebook.com>
Date:   Fri, 13 May 2022 12:14:59 -0700
From:   David Vernet <void@...ifault.com>
To:     Michal Koutný <mkoutny@...e.com>
Cc:     akpm@...ux-foundation.org, cgroups@...r.kernel.org,
        hannes@...xchg.org, kernel-team@...com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        mhocko@...nel.org, roman.gushchin@...ux.dev, shakeelb@...gle.com,
        tj@...nel.org, Richard Palethorpe <rpalethorpe@...e.de>
Subject: Re: [PATCH 4/4] selftests: memcg: Remove protection from top level
 memcg

On Fri, May 13, 2022 at 07:18:11PM +0200, Michal Koutný wrote:
> The reclaim is triggered by memory limit in a subtree, therefore the
> testcase does not need configured protection against external reclaim.
> 
> Also, correct/deduplicate respective comments
> 
> Signed-off-by: Michal Koutný <mkoutny@...e.com>
> ---
>  tools/testing/selftests/cgroup/test_memcontrol.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
> index 9ffacf024bbd..9d370aafd799 100644
> --- a/tools/testing/selftests/cgroup/test_memcontrol.c
> +++ b/tools/testing/selftests/cgroup/test_memcontrol.c
> @@ -247,7 +247,7 @@ static int cg_test_proc_killed(const char *cgroup)
>  
>  /*
>   * First, this test creates the following hierarchy:
> - * A       memory.min = 50M,  memory.max = 200M
> + * A       memory.min = 0,    memory.max = 200M
>   * A/B     memory.min = 50M,  memory.current = 50M
>   * A/B/C   memory.min = 75M,  memory.current = 50M
>   * A/B/D   memory.min = 25M,  memory.current = 50M
> @@ -257,7 +257,7 @@ static int cg_test_proc_killed(const char *cgroup)
>   * Usages are pagecache, but the test keeps a running
>   * process in every leaf cgroup.
>   * Then it creates A/G and creates a significant
> - * memory pressure in it.
> + * memory pressure in A.
>   *
>   * A/B    memory.current ~= 50M
>   * A/B/C  memory.current ~= 29M
> @@ -335,8 +335,6 @@ static int test_memcg_min(const char *root)
>  			      (void *)(long)fd);
>  	}
>  
> -	if (cg_write(parent[0], "memory.min", "50M"))
> -		goto cleanup;
>  	if (cg_write(parent[1], "memory.min", "50M"))
>  		goto cleanup;
>  	if (cg_write(children[0], "memory.min", "75M"))
> @@ -404,8 +402,8 @@ static int test_memcg_min(const char *root)
>  
>  /*
>   * First, this test creates the following hierarchy:
> - * A       memory.low = 50M,  memory.max = 200M
> - * A/B     memory.low = 50M,  memory.current = 50M
> + * A       memory.low = 0,    memory.max = 200M
> + * A/B     memory.low = 50M,  memory.current = ...

Is there a reason that we would adjust this comment but not the A/B comment
from above in from test_memcg_low()? In both cases, I would just remove the
memory.current = ... part altogether, as Roman suggested.

>   * A/B/C   memory.low = 75M,  memory.current = 50M
>   * A/B/D   memory.low = 25M,  memory.current = 50M
>   * A/B/E   memory.low = 0,    memory.current = 50M
> @@ -490,8 +488,6 @@ static int test_memcg_low(const char *root)
>  			goto cleanup;
>  	}
>  
> -	if (cg_write(parent[0], "memory.low", "50M"))
> -		goto cleanup;
>  	if (cg_write(parent[1], "memory.low", "50M"))
>  		goto cleanup;
>  	if (cg_write(children[0], "memory.low", "75M"))
> -- 
> 2.35.3
> 

Looks good otherwise.

Reviewed-by: David Vernet <void@...ifault.com>