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t=1785846100; bh=efM8AzxF8bqG1DJUbVqdvBnISyKCHBsMBtlf3nlIbeI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=NktLoOFfZHRqade73gsXm7Fzc5b4FzLM4PGUbDUVlnpQDQaw8N/f5k913OBECAMbI +HrQpHcH7kDUKErVLUGaVf8BOsenwxAhTCnJ80Zi5Y7vJ6KHLTaXYeUYtg7wj5C5QO GCXA1aFt9zsiU7VML2j8AYS+RfVV1MGt1/1WdSDJlK4LpEcPWMi/wERqDgID67QlVy L8Hfby7sAl47LHuEj/hmDV/a7JU6j+aAxepgJJyJy5TTrSIGSke3tTYNcRIXOLYAnJ gL/KHnJ1olazm74vu3gaqMYB77bCAyXV3Ykv8NmW1cOye60bJmQTydS7rzQmMC6BYV s/W9MW/K/Rx1A== Message-ID: <6193876b-adcf-4cc5-9101-67454a359053@kernel.org> Date: Tue, 4 Aug 2026 14:21:36 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] 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> <1785845818-3131-1-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 X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 68D021C000E X-Stat-Signature: 44x3wm74arpx4wbsn1sq5mdmp11xyhii X-Rspam-User: X-HE-Tag: 1785846101-20606 X-HE-Meta: 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 TrM0+n9u NYVGKSxjsHwmx2nNcD3HdXBLvU3b3emrI07azSeTOoJwoRwEzMjvEnMEJG55meEmWPQwc8XPFzWhQQi/wmMyAT6v5S92+bMbAM0umHzls/bYXq2LnVAZl4Cwg0G6EQXIv8DODwohE4dslJRMwOrQbJwCFl5vfItb+bo06wMHBNKhO+4wbB8jcruVpPCOFwD/sGPhO+aJJECp60/ILEKAx5WMVFKkPpPJ5xYKR+b5n8MVSOZaMZ7qD1an//5n2B0TjDKLwR9E27ttJ/1/HOeoZcHnL6FLkMKd9O1VGhH9T3ibntwm2qaa6izdxfFYyigYWw0T5BI5FIr//NgxPvks8kZWmUA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/4/26 14:16, 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 > --- > Changes in v2: > - Replace the two boolean flags with a hit counter, as suggested by > David Hildenbrand. > > v1: https://lore.kernel.org/1785720615-5826-1-git-send-email-warren.xiong@ugreen.com/ > > tools/testing/selftests/mm/compaction_test.c | 38 +++++++++++++++------------- > 1 file changed, 21 insertions(+), 17 deletions(-) > > diff --git a/tools/testing/selftests/mm/compaction_test.c b/tools/testing/selftests/mm/compaction_test.c > index 5b58258..30d4ace 100644 > --- a/tools/testing/selftests/mm/compaction_test.c > +++ b/tools/testing/selftests/mm/compaction_test.c > @@ -29,30 +29,34 @@ struct map_list { > > int read_memory_info(unsigned long *memfree, unsigned long *hugepagesize) > { > - char buffer[256] = {0}; > - char *cmd = "cat /proc/meminfo | grep -i memfree | grep -o '[0-9]*'"; > - FILE *cmdfile = popen(cmd, "r"); > + char buffer[256]; > + int found = 0; > + 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); > - > - *memfree = atoll(buffer); > - cmd = "cat /proc/meminfo | grep -i hugepagesize | grep -o '[0-9]*'"; > - cmdfile = popen(cmd, "r"); > - > - if (!(fgets(buffer, sizeof(buffer), cmdfile))) { > - ksft_print_msg("Failed to read meminfo: %s\n", strerror(errno)); > - return -1; > + while (fgets(buffer, sizeof(buffer), file) && found != 2) { > + if (sscanf(buffer, "MemFree: %lu kB", memfree) == 1 || > + sscanf(buffer, "Hugepagesize: %lu kB", hugepagesize) == 1) > + found++; Just as information: when proposing that I was assuming that we would never ever have two times the same entry in /proc/meminfo, which i think we can reasonably assume. Thanks! Acked-by: David Hildenbrand (Arm) -- Cheers, David