linux-kernel - Re: [PATCH v2] selftests: cgroup: fix test_kmem_memcg

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Message-ID: <20230817170702.mwem4nsy2ka4gj7n@google.com>
Date:   Thu, 17 Aug 2023 17:07:02 +0000
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Lucas Karpinski <lkarpins@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Muchun Song <muchun.song@...ux.dev>, Tejun Heo <tj@...nel.org>,
        Zefan Li <lizefan.x@...edance.com>,
        Shuah Khan <shuah@...nel.org>, cgroups@...r.kernel.org,
        linux-mm@...ck.org, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] selftests: cgroup: fix test_kmem_memcg_deletion kernel
 mem check

On Thu, Aug 17, 2023 at 08:47:26AM -0400, Lucas Karpinski wrote:
> The combination of using slab, anon, file, kernel_stack, and percpu is
> not accurate for total kernel memory utilization. Checking kernel within
> memory.stat provides a more accurate measurement.
> 
> Signed-off-by: Lucas Karpinski <lkarpins@...hat.com>
> ---
>  v1: https://lore.kernel.org/all/eex2vdlg4ow2j5bybmav73nbfzuspkk4zobnk7svua4jaypqb5@7ie6e4mci43t/
> 
>  tools/testing/selftests/cgroup/test_kmem.c | 25 +++++-----------------
>  1 file changed, 5 insertions(+), 20 deletions(-)
> 
> diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c
> index ed2e50bb1e76..3ef979ee0edf 100644
> --- a/tools/testing/selftests/cgroup/test_kmem.c
> +++ b/tools/testing/selftests/cgroup/test_kmem.c
> @@ -166,7 +166,7 @@ static int cg_run_in_subcgroups(const char *parent,
>   */
>  static int test_kmem_memcg_deletion(const char *root)
>  {
> -	long current, slab, anon, file, kernel_stack, pagetables, percpu, sock, sum;
> +	long current, kernel;
>  	int ret = KSFT_FAIL;
>  	char *parent;
>  
> @@ -184,30 +184,15 @@ static int test_kmem_memcg_deletion(const char *root)
>  		goto cleanup;
>  
>  	current = cg_read_long(parent, "memory.current");
> -	slab = cg_read_key_long(parent, "memory.stat", "slab ");
> -	anon = cg_read_key_long(parent, "memory.stat", "anon ");
> -	file = cg_read_key_long(parent, "memory.stat", "file ");
> -	kernel_stack = cg_read_key_long(parent, "memory.stat", "kernel_stack ");
> -	pagetables = cg_read_key_long(parent, "memory.stat", "pagetables ");
> -	percpu = cg_read_key_long(parent, "memory.stat", "percpu ");
> -	sock = cg_read_key_long(parent, "memory.stat", "sock ");
> -	if (current < 0 || slab < 0 || anon < 0 || file < 0 ||
> -	    kernel_stack < 0 || pagetables < 0 || percpu < 0 || sock < 0)
> +	kernel = cg_read_key_long(parent, "memory.stat", "kernel ");
> +	if (current < 0 || kernel < 0)
>  		goto cleanup;
>  
> -	sum = slab + anon + file + kernel_stack + pagetables + percpu + sock;
> -	if (abs(sum - current) < MAX_VMSTAT_ERROR) {
> +	if (abs(kernel - current) < MAX_VMSTAT_ERROR) {

I don't think this is what you want. Since slab, kernel_stack,
pagetables and percpu are included in the kmem stats, you just want to
replace those with kmem. Basically keep the anon, file and sock stats.