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selftests: cgroup: update per-memcg zswap writeback selftest 

The memcg-zswap self test is updated to adjust to the behavior change
implemented by commit 87730b165089 ("zswap: make shrinking memcg-aware"),
where zswap performs writeback for specific memcg.

Link: https://lkml.kernel.org/r/20231130194023.4102148-6-nphamcs@gmail.com
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Acked-by: Chris Li <chrisl@kernel.org> (Google)
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Domenico Cerasuolo 2023-11-30 11:40:22 -08:00 committed by Andrew Morton
parent 7108cc3f76
commit a697dc2be9
1 changed files with 51 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
tools/testing/selftests/cgroup/test_zswap.c
View File

@ -50,9 +50,9 @@ static int get_zswap_stored_pages(size_t *value)
return read_int("/sys/kernel/debug/zswap/stored_pages", value);
}
static int get_zswap_written_back_pages(size_t *value)
static int get_cg_wb_count(const char *cg)
{
return read_int("/sys/kernel/debug/zswap/written_back_pages", value);
return cg_read_key_long(cg, "memory.stat", "zswp_wb");
}
static long get_zswpout(const char *cgroup)
@ -73,6 +73,24 @@ static int allocate_bytes(const char *cgroup, void *arg)
return 0;
}
static char *setup_test_group_1M(const char *root, const char *name)
{
char *group_name = cg_name(root, name);
if (!group_name)
return NULL;
if (cg_create(group_name))
goto fail;
if (cg_write(group_name, "memory.max", "1M")) {
cg_destroy(group_name);
goto fail;
}
return group_name;
fail:
free(group_name);
return NULL;
}
/*
* Sanity test to check that pages are written into zswap.
*/
@ -117,43 +135,51 @@ out:
/*
* When trying to store a memcg page in zswap, if the memcg hits its memory
* limit in zswap, writeback should not be triggered.
*
* This was fixed with commit 0bdf0efa180a("zswap: do not shrink if cgroup may
* not zswap"). Needs to be revised when a per memcg writeback mechanism is
* implemented.
* limit in zswap, writeback should affect only the zswapped pages of that
* memcg.
*/
static int test_no_invasive_cgroup_shrink(const char *root)
{
size_t written_back_before, written_back_after;
int ret = KSFT_FAIL;
char *test_group;
size_t control_allocation_size = MB(10);
char *control_allocation, *wb_group = NULL, *control_group = NULL;
/* Set up */
test_group = cg_name(root, "no_shrink_test");
if (!test_group)
wb_group = setup_test_group_1M(root, "per_memcg_wb_test1");
if (!wb_group)
return KSFT_FAIL;
if (cg_write(wb_group, "memory.zswap.max", "10K"))
goto out;
if (cg_create(test_group))
goto out;
if (cg_write(test_group, "memory.max", "1M"))
goto out;
if (cg_write(test_group, "memory.zswap.max", "10K"))
goto out;
if (get_zswap_written_back_pages(&written_back_before))
control_group = setup_test_group_1M(root, "per_memcg_wb_test2");
if (!control_group)
goto out;
/* Allocate 10x memory.max to push memory into zswap */
if (cg_run(test_group, allocate_bytes, (void *)MB(10)))
/* Push some test_group2 memory into zswap */
if (cg_enter_current(control_group))
goto out;
control_allocation = malloc(control_allocation_size);
for (int i = 0; i < control_allocation_size; i += 4095)
control_allocation[i] = 'a';
if (cg_read_key_long(control_group, "memory.stat", "zswapped") < 1)
goto out;
/* Verify that no writeback happened because of the memcg allocation */
if (get_zswap_written_back_pages(&written_back_after))
/* Allocate 10x memory.max to push wb_group memory into zswap and trigger wb */
if (cg_run(wb_group, allocate_bytes, (void *)MB(10)))
goto out;
if (written_back_after == written_back_before)
/* Verify that only zswapped memory from gwb_group has been written back */
if (get_cg_wb_count(wb_group) > 0 && get_cg_wb_count(control_group) == 0)
ret = KSFT_PASS;
out:
cg_destroy(test_group);
free(test_group);
cg_enter_current(root);
if (control_group) {
cg_destroy(control_group);
free(control_group);
}
cg_destroy(wb_group);
free(wb_group);
if (control_allocation)
free(control_allocation);
return ret;
}