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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 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 X-Rspamd-Queue-Id: 7965F10000D X-Rspam-User: X-Stat-Signature: ppmr61jsmjkjodxkwabeit3ch8wy9edd X-Rspamd-Server: rspam03 X-HE-Tag: 1784124573-874084 X-HE-Meta: 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 6RolUA/X LgGBHW9yz8V4tf4E9tBeTtoshOxTlXUeol/k0w6m+LC81mFN31YVYy8ar4kUTY6kSsxDGeLk06V7gza8F97TnIESAGMZeEPS8LKQ1SrngVRtAbjGE948eFR74OD9kDLY3fFa0ghjXO4nYVuIfSWhEhrhzw86yoY+GO3qyteC09P8wVO75MeRAW9tfMRElqp3lJo2T6Pi4XDtUK+ZL/RAzFte8ZTkgNfMc8TOr9H+Ts52oV1/WQwRBRcH5twrEhTgsdikCR+GfYdUhA7B+hIqxzbQhsGBYrCWp9fHwOQDB2OPqHDlN99GxSvCNbKQm6ZM/cBrSa9eYQ/x3MozKmlPdJg1eJLZP98I9rIhl Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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