From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3F2B039936F; Mon, 23 Mar 2026 11:56:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774266998; cv=none; b=rtUCg8Si93n53uO6wlHmbi9y5Sp7KrY822K/6HNTk2KRKI2uDBRpY3+8etve7aOuu5QKkSw7RtJL1L79wyCi14R/hDkSUuqaj8uQM0//pNNYTAZhCJop7ln/wA2Z/SgI9nOg06+W2nlJU6uFyYfFtsvZVtPKEdsOfTyzZ3NJaX4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774266998; c=relaxed/simple; bh=0DqT45wHIWJCNhvxa30ejAPQrE5LelMtMNTQg4f6hjw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=uuRj2wGuRjps/0fcJ3MIcqsknfXt54oPhBiYsCGGpG+qoDXzoNx78cOZu8X4uFwbm6bl7QgrGm/FnIAlansBOcqXYtl6Pa4JX114jJrF1jz7Mu/Esydghjs/NIQxCtR8Tu1bgmAZxVBDLkbktQkCxPSA2V5Ljlc3NCIYIcJ5GsI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u/OMXgWu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="u/OMXgWu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D640C2BCB1; Mon, 23 Mar 2026 11:56:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774266998; bh=0DqT45wHIWJCNhvxa30ejAPQrE5LelMtMNTQg4f6hjw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=u/OMXgWu+chO3gvSI12/PPBLGLAG6Xmt6zeic+C0lrMmuuBOFfaJ6NcDr3wEsVEVc EBqviFGr9mMYUGB9SRrwlDRUmyhf06XUyR8nhG95dPymq1tt/woI00vES7KjJgA4zd JhAPgv0JIj7NDVGlazIOCO5TSvA8lTlL1X8XNjI44EYzACpCeCk1d2DwUqW8VStSyI nvu1TAWAspCQtHJo7kjF5KHQBnkrAp41psY4G3AflGpg+hnQUCwvE7aFg0NlOyTUjJ mi/rXt8Z3sz0FkVowK9jcQX2aE7+euJiZyT170qfAwD1tXz/RQVkpf7HT+xUkYBXWE B7ca6w+Ds4q+A== Message-ID: Date: Mon, 23 Mar 2026 12:56:33 +0100 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] selftests/mm: Fix soft-dirty kselftest supported check To: Audra Mitchell , akpm@linux-foundation.org Cc: ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org, usama.anjum@collabora.com, colin.i.king@gmail.com, avagin@google.com, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260320184010.759461-1-audra@redhat.com> <20260320184010.759461-2-audra@redhat.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/20/26 19:39, Audra Mitchell wrote: > On architectures with separate user address space, such as s390 or > those without an MMU, the soft-dirty kselftest may fail when checking > to see if the feature is supported. > > # -------------------- > # running ./soft-dirty > # -------------------- > # TAP version 13 > # 1..15 > # Bail out! PAGEMAP_SCAN succeeded unexpectedly > # # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0 > # [FAIL] > not ok 1 soft-dirty # exit=1 > # SUMMARY: PASS=0 SKIP=0 FAIL=1 > > The soft-dirty test will initate an ioctl with the PAGEMAP_SCAN flag with > an invalid address for the page_region. This is done intentionally to > have the ioctl return with an expected EFAULT and with the correct > categories returned. > > However, on architectures with separate user address space, such as s390 or > those without an MMU, the call to __access_ok (used to validate the > variables provided with the ioctl) will always return true and we will not > fail as expected. > > if (IS_ENABLED(CONFIG_ALTERNATE_USER_ADDRESS_SPACE) || > !IS_ENABLED(CONFIG_MMU)) > return true; > > Let's simplify the check for PAGEMAP_SCAN and provide a valid page_region > address so that we get a non-errno return if it is supported. > > Fixes: 600bca580579 ("selftests/mm: check that PAGEMAP_SCAN returns correct categories") > > Signed-off-by: Audra Mitchell > --- > tools/testing/selftests/mm/vm_util.c | 24 +++++++++++++++--------- > 1 file changed, 15 insertions(+), 9 deletions(-) > > diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c > index a6d4ff7dfdc0..82998406b335 100644 > --- a/tools/testing/selftests/mm/vm_util.c > +++ b/tools/testing/selftests/mm/vm_util.c > @@ -67,20 +67,26 @@ static uint64_t pagemap_scan_get_categories(int fd, char *start) > } > > /* `start` is any valid address. */ > -static bool pagemap_scan_supported(int fd, char *start) > +static bool pagemap_scan_supported(int fd) > { > + const size_t pagesize = getpagesize(); > static int supported = -1; > - int ret; > + struct page_region r; > + void *test_area; > > if (supported != -1) > return supported; > > - /* Provide an invalid address in order to trigger EFAULT. */ > - ret = __pagemap_scan_get_categories(fd, start, (struct page_region *) ~0UL); > - if (ret == 0) > - ksft_exit_fail_msg("PAGEMAP_SCAN succeeded unexpectedly\n"); > - > - supported = errno == EFAULT; > + test_area = mmap(0, pagesize, PROT_READ | PROT_WRITE, > + MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); > + if (test_area == MAP_FAILED) { > + ksft_print_msg("WARN: mmap() failed: %s\n", strerror(errno)); > + supported = 0; > + } else { > + supported = __pagemap_scan_get_categories(fd, test_area, &r) >= 0; You have to cast it to a (long) first before comparing, like we do in pagemap_scan_get_categories(). Maybe best written as long ret = __pagemap_scan_get_categories(fd, test_area, &r); if (ret >= 0) supported = 1; > + ksft_print_msg("errno: %d\n", errno); I guess we should drop that, was mostly for testing. Thanks! -- Cheers, David