Re: [PATCH 2/4] selftest/arm64: Treat KSM merge_across_nodes as optional

On 20/08/2026 5:09 pm, Mark Brown wrote:

On Thu, Aug 20, 2026 at 04:33:24PM +0100, Muhammad Usama Anjum wrote:

quoted

The MTE KSM test unconditionally saves, enables and restores the
merge_across_nodes sysfs attribute. The kernel only creates this
attribute when CONFIG_NUMA=y. A non-NUMA kernel consequently prints the
following message three times even though all KSM subtests pass:

quoted

 static void mte_ksm_setup(void)
 {
-	ksm_sysfs[0] = read_sysfs(PATH_KSM "merge_across_nodes");
-	write_sysfs(PATH_KSM "merge_across_nodes", 1);
+	has_merge_across_nodes = !access(PATH_KSM "merge_across_nodes", F_OK);

Don't we need the file to be readable and writable, not just extant?

Correct, I'll fix it.

Looking quickly at the test I'm actually not spotting where it checks
that it's running as root which I think it needs in general.

I'll add check for that as well.

-- 
Thanks,
Usama