[LTP] futex_wait06: Add EFAULT error coverage test

[linuxtestproject.agent@gmail.com]

Hi Michael,

All four patches are missing a commit body and Signed-off-by tag.
Please add at least one sentence explaining why each test is being added
(gap in coverage, related kernel change, regression, etc.), and add
your Signed-off-by trailer to each commit.

--- [PATCH 4/4] ---

On Wed, 6 May 2026 18:18:01 +0300, Michael Menasherov wrote:
> futex_cmp_requeue03: Add EFAULT and EACCES error coverage test

> + * The EACCES behavior for PROT_NONE was introduced in kernel 5.9.

> +		.exp_errno = tst_kvercmp(5, 9, 0) >= 0 ? EACCES : EFAULT,

I cannot find a kernel code path that returns -EACCES for a PROT_NONE
futex address. get_futex_key() in kernel/futex/core.c returns -EFAULT
when get_user_pages_fast() fails on an inaccessible page, regardless of
whether the failure is due to unmapped or PROT_NONE memory. Please cite
the specific kernel commit that introduced this behaviour, or replace the
conditional with unconditional EFAULT.

[...]

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