On Thu, Apr 21, 2022 at 11:44:26PM +0000, Yosry Ahmed wrote:
> Add a new test for memory.reclaim that verifies that the interface
> correctly reclaims memory as intended, from both anon and file pages.
>
> Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
> Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
> ---
> .../selftests/cgroup/test_memcontrol.c | 86 +++++++++++++++++++
> 1 file changed, 86 insertions(+)
>
> diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
> index f2ffb3a30194..5f7c20de2426 100644
> --- a/tools/testing/selftests/cgroup/test_memcontrol.c
> +++ b/tools/testing/selftests/cgroup/test_memcontrol.c
> @@ -760,6 +760,91 @@ static int test_memcg_max(const char *root)
> return ret;
> }
>
> +/*
> + * This test checks that memory.reclaim reclaims the given
> + * amount of memory (from both anon and file).
> + */
> +static int test_memcg_reclaim(const char *root)
> +{
> + int ret = KSFT_FAIL, fd, retries;
> + char *memcg;
> + long current, to_reclaim;
> + char buf[64];
> +
> + memcg = cg_name(root, "memcg_test");
> + if (!memcg)
> + goto cleanup;
> +
> + if (cg_create(memcg))
> + goto cleanup;
> +
> + current = cg_read_long(memcg, "memory.current");
> + if (current != 0)
> + goto cleanup;
> +
> + cg_run_nowait(memcg, alloc_anon_noexit, (void *) MB(50));
Don't you need is_swap_enabled() check before deciding to do the anon
allocations?
> + sleep(1);
> +
> + fd = get_temp_fd();
> + if (fd < 0)
> + goto cleanup;
> +
> + cg_run_nowait(memcg, alloc_pagecache_50M_noexit, (void *)(long)fd);
> + sleep(1);
These sleep(1)s do not seem robust. Since kernel keeps the page cache
around, you can convert anon to use tmpfs and use simple cg_run to
trigger the allocations of anon (tmpfs) and file which will remain in
memory even after return from cg_run.
