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

[Mark Brown]

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

>  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?
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.
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