From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 86BB6320A04; Wed, 15 Jul 2026 14:09:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784124573; cv=none; b=IKtTg9ziTLirDHUXfZzxnUYzThzi7vdw6K12ME7HV/MiQN8Muwq2FrpbudoCqUqH3O5fH49vZVaCg3mcmy7K59QrSBCc7sI6GMHqQqjPZzHXQf6lPdFmDlVJPY2WtJrzwohw+OBzHPMEiPpENmPbN3c/WXUEEYH87p6P+KGG77Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784124573; c=relaxed/simple; bh=CgguALGX5s5qVXVNsTE0W3mSBt3jjbtU1cdRAWhNAgs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=uM8R0T+8OKmmJuvWEICr8hqomaNzO/1plJ9nQ/NAiL4sFXZmwk+G+teX/IHBJjGZX8NWoEqe1/ARJqap6uCTHqGFKa9ycd4ZJ2nw/OK62awbM4Vgs6Zh/m6OhfG63EbjHcyNcqCcUv8f0scOtdoB5jkjKDbsraaemHZzp/yfgsQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JsMhAAJu; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JsMhAAJu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31E091F00A3A; Wed, 15 Jul 2026 14:09:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784124572; bh=fmLajELBwebxH7WxDXtone4cRwMQnjq82TSthiZG3yo=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=JsMhAAJuy0UKuZYDWb8ZyxBhcEuXGK7+4HoxA4WQGGFilUXJaziL3rUg7N0l8O0oY yaHX8HnIfERUujyI5L5IhE9tZnSNQCC9KcTHx5qoAAjZ52vBqwR8KuPqodpd61mKEm D+s4P+6SRTeGylndvOLiBBr09KD1cbI666l3fAuMwv6q6DmrbSdwMCCqScrRl4y/yp 50wFx4hlc0cVgyHkMrDAgkeTNMowmF4oFjCFbi4LK+SXX4YwLZ2Jisj6DWDGZ28TKn C9r9i4lyMv+fR7kGR501lTKkzRkVtYaLFNeuaUFm8JbK0ISqN8kBErZFDitcqKdX2f jSIxL3z9xKN1g== Message-ID: <4b6904b5-81f9-4e27-8ac5-5bd7e7174c5d@kernel.org> Date: Wed, 15 Jul 2026 16:09:29 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] selftests/mm: khugepaged: skip swap tests when swap is unavailable To: Jaeyeon Lee , Andrew Morton , Shuah Khan Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260715133418.170386-1-jaeyeon.lee.dev@gmail.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 7/15/26 15:34, Jaeyeon Lee wrote: > The collapse_swapin_single_pte and collapse_max_ptes_swap tests use > MADV_PAGEOUT to swap out pages before verifying khugepaged collapse > behavior. On systems without swap configured, MADV_PAGEOUT succeeds > but the pages are not actually swapped out, so check_swap() returns > false and the tests report a failure. > > These tests cannot run meaningfully without swap, so a missing swap > area is an environment limitation rather than a test failure. Detect > the absence of swap via /proc/swaps and skip the affected tests > instead of failing them. > > Signed-off-by: Jaeyeon Lee > --- > tools/testing/selftests/mm/khugepaged.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c > index 10e8dedcb087..f9b4ebe733ce 100644 > --- a/tools/testing/selftests/mm/khugepaged.c > +++ b/tools/testing/selftests/mm/khugepaged.c > @@ -100,6 +100,22 @@ static void skip(const char *msg) > exit_status = KSFT_SKIP; > } > > +static bool swap_available(void) > +{ > + char buf[256]; > + bool ret; > + FILE *fp = fopen("/proc/swaps", "r"); > + > + if (!fp) > + return false; > + > + fgets(buf, sizeof(buf), fp); > + ret = !!fgets(buf, sizeof(buf), fp); > + > + fclose(fp); > + return ret; > +} > + That doesn't mean that swapout will succeed. Take a look at cow.c where we use pagemap_is_swapped() after MADV_PAGEOUT. -- Cheers, David