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 03DD930648A; Tue, 4 Aug 2026 11:15:39 +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=1785842141; cv=none; b=WgpdzbdMcseFeoAFxWYZ0z+Dzt8uo7Q1hIizzfSV1x4RttJWoVVh7cwX4a4DxTJtJ2CbjZYx9sjb7QHl/YbVtLGIMeKza7T+OG72rykuiEIbNQNRsPHK0AJGiFhwmcEgzPCkYcu1UY43EeARfVphFqAX26DTO0XOocK5ZbipPis= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785842141; c=relaxed/simple; bh=N3bwa8ZHxA0MBj3Y7BYxE34jWXc3OcUrebu2y0/4WN8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Hhj26n6bjySVgws8tXRX7qDSQWv+45WaaF6/DpTmmpAYzfPYdkPWkIriBUSdGe78FZDPkG5vM8/F0WxZkvcRa/9/2Kbb64rehL6LL0wkfAW4LgraDwoEYUjswCagyh78Yls/TgmHWyCps3BcBVXZosk+kRsy3Kl7nwjvMBVaNMw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fpUyrcce; 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="fpUyrcce" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8C8E1F000E9; Tue, 4 Aug 2026 11:15:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785842139; bh=vcsWgIMR7LcCcHyHDDAzBXTohXszChMU8dODqlMuHUA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=fpUyrccezzAi7StCsPWHMjl/bBFU/mYE9zeoFCdP2TQ7/90JDdlTQjDnRMmrexzZI 088Yco0PlOY2OU4VtNP7eiG4V1Tc+eTRgl19QTmRd1cdFVcwQ97W7zE4flW3Ziob5b nAh8+RA/G3Eb/GFKglpnfjHDuzLEDj3kl8AuBRd3uBoRG1XMRs2/ZnpC+Fhu4PEf17 00eb7DUZgV2WUc60Thg5Qp8zQZD1uMXSMqPJHo3GscOjmZ8G8BmJrgZTj0BbP416Ck Kp/H935KeBNUWfzR2uD4BBKJ8OhB2AL2ag2P454OcLhQjWY14mNSf1Q9L90f/v4sC2 JydcHyThErBGA== Message-ID: <9dc3b457-65aa-40ba-99a1-7c703facbd32@kernel.org> Date: Tue, 4 Aug 2026 13:15:35 +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: read memory information without popen To: Warren Xiong , akpm@linux-foundation.org, shuah@kernel.org Cc: ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org References: <1785720615-5826-1-git-send-email-warren.xiong@ugreen.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 8/3/26 03:30, Warren Xiong wrote: > read_memory_info() invokes two shell pipelines to obtain MemFree and > Hugepagesize from /proc/meminfo. It does not check whether popen() > returns NULL before passing the result to fgets(), and it does not call > pclose() when fgets() fails. > > Open /proc/meminfo directly and obtain both values in a single pass. > This removes the unchecked NULL path, closes the file on all paths, and > avoids dependencies on external commands. > > The compaction test continues to pass after this change. > > Signed-off-by: Warren Xiong > --- > tools/testing/selftests/mm/compaction_test.c | 43 +++++++++++++++++----------- > 1 file changed, 27 insertions(+), 16 deletions(-) > > diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c > index 5b58258..0df2000 100644 > --- a/tools/testing/selftests/mm/compaction_test.c > +++ b/tools/testing/selftests/mm/compaction_test.c > @@ -7,6 +7,7 @@ > * allocated. > */ > > +#include > #include > #include > #include > @@ -29,30 +30,40 @@ struct map_list { > > int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize) > { Looks much better indeed. > - char buffer[256] = {0}; > - char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'"; > - FILE *cmdfile = popen(cmd, "r"); > + char buffer[256]; > + bool memfree_found = false; > + bool hugepagesize_found = false; > + FILE *file; > + int ret = -1; > > - if (!(fgets(buffer, sizeof(buffer), cmdfile))) { > - ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno)); > + file = fopen("/proc/meminfo", "r"); > + if (!file) { > + ksft_print_msg("Failed to open /proc/meminfo: %s\n", > + strerror(errno)); > return -1; > } > > - pclose(cmdfile); > + while (fgets(buffer, sizeof(buffer), file)) { > + if (sscanf(buffer, "MemFree: %lu kB", memfree) == 1) > + memfree_found = true; > + else if (sscanf(buffer, "Hugepagesize: %lu kB", > + hugepagesize) == 1) > + hugepagesize_found = true; Instead of these bools you could just have a hit-count. Like the following on top: diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c index 0df2000f4a2b1..30d4ace7155ae 100644 --- a/tools/testing/selftests/mm/compaction_test.c +++ b/tools/testing/selftests/mm/compaction_test.c @@ -7,7 +7,6 @@ * allocated. */ -#include #include #include #include @@ -31,8 +30,7 @@ struct map_list { int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize) { char buffer[256]; - bool memfree_found = false; - bool hugepagesize_found = false; + int found = 0; FILE *file; int ret = -1; @@ -43,24 +41,19 @@ int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize) return -1; } - while (fgets(buffer, sizeof(buffer), file)) { - if (sscanf(buffer, "MemFree: %lu kB", memfree) == 1) - memfree_found = true; - else if (sscanf(buffer, "Hugepagesize: %lu kB", - hugepagesize) == 1) - hugepagesize_found = true; - - if (memfree_found && hugepagesize_found) { - ret = 0; - break; - } + while (fgets(buffer, sizeof(buffer), file) && found != 2) { + if (sscanf(buffer, "MemFree: %lu kB", memfree) == 1 || + sscanf(buffer, "Hugepagesize: %lu kB", hugepagesize) == 1) + found++; } if (ferror(file)) ksft_print_msg("Failed to read /proc/meminfo: %s\n", strerror(errno)); - else if (ret) + else if (found != 2) ksft_print_msg("Failed to parse /proc/meminfo\n"); + else + ret = 0; fclose(file); return ret; -- Cheers, David