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

Andrew Morton
2022-05-18T00:24:43Z

On Fri, 13 May 2022 11:59:56 -0700 Roman Gushchin <roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org> wrote:

> On Fri, May 13, 2022 at 07:18:11PM +0200, Michal Koutny 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-IBi9RG/b67k@public.gmane.org>
> > ---
> > 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 = ...
>
> Can you, please, just remove "memory.current = ...", it's not
> because obvious what "..." means here.
>

You mean this?

--- a/tools/testing/selftests/cgroup/test_memcontrol.c~selftests-memcg-remove-protection-from-top-level-memcg-fix
+++ a/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -403,15 +403,14 @@ cleanup:
/*
* First, this test creates the following hierarchy:
* A memory.low = 0, memory.max = 200M
- * A/B memory.low = 50M, memory.current = ...
+ * A/B memory.low = 50M
* 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
* A/B/F memory.low = 500M, memory.current = 0
*
* Usages are pagecache.
- * Then it creates A/G an creates a significant
- * memory pressure in it.
+ * Then it creates A/G and creates significant memory pressure in it.
*
* Then it checks actual memory usages and expects that:
* A/B memory.current ~= 50M
_

(includes gratuitous comment cleanup)

I assume your comment in
https://lkml.kernel.org/r/Yn6pBPq+lAXm9NG8@carbon can be addressed in a
later patch.

I'm not sure what to amke of https://lkml.kernel.org/r/Yn6pWPodGPlz+D8G@carbon

Do we feel this series needs more work before merging it up?