On Tue, 11 Aug 2026 05:14:11 +0000 Wilson Felipe Pereira <[email protected]>
wrote:
> test_no_kmem_bypass() needs to read
> /sys/kernel/debug/zswap/stored_pages via get_zswap_stored_pages() to
> verify that compressed pages are charged to the memcg.
>
> When running in an environment where debugfs is not mounted or
> CONFIG_DEBUG_FS is disabled, get_zswap_stored_pages() fails, causing the
> loop to terminate early and report a false negative (KSFT_FAIL).
>
> Selftests should not fail if debugfs is unavailable, and it should print
> a message when it is skipped.
>
> While I'm here, also add a warning message if the test is being skipped
> due to totalram size and make the check for totalram more readable.
>
> ...
>
> --- a/tools/testing/selftests/cgroup/lib/include/cgroup_util.h
> +++ b/tools/testing/selftests/cgroup/lib/include/cgroup_util.h
>
> ...
>
> @@ -570,8 +571,16 @@ static int test_no_kmem_bypass(const char *root)
> /* Read sys info and compute test values accordingly */
> if (sysinfo(&sys_info) != 0)
> return KSFT_FAIL;
> - if (sys_info.totalram > 5000000000)
> + if (sys_info.totalram > GB(4)) {
> + ksft_print_msg(
> + "requires less than 4GB total ram, sys_info.totalram:
> %.1fGB\n",
> + (double)sys_info.totalram / GB(1));
> return KSFT_SKIP;
> + }
> + if (access(PATH_ZSWAP_STORED_PAGES, R_OK)) {
> + ksft_print_msg("mount debugfs at /sys/kernel/debug\n");
Super nittynit: "mount debugfs at /sys/kernel/debug" sounds like a
progress message. "I just mounted debugfs at ...". I think the below is
more clear?
---
a/tools/testing/selftests/cgroup/test_zswap.c~selftests-cgroup-test_zswap-skip-test_no_kmem_bypass-if-debugfs-is-unavailable-fix
+++ a/tools/testing/selftests/cgroup/test_zswap.c
@@ -578,7 +578,7 @@ static int test_no_kmem_bypass(const cha
return KSFT_SKIP;
}
if (access(PATH_ZSWAP_STORED_PAGES, R_OK)) {
- ksft_print_msg("mount debugfs at /sys/kernel/debug\n");
+ ksft_print_msg("debugfs not mounted at /sys/kernel/debug\n");
return KSFT_SKIP;
}
values = mmap(0, sizeof(struct no_kmem_bypass_child_args), PROT_READ |
_
