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b=cO4jAMG2t8RFD2STp4VqH1DZPCjpAKkI8Gg14qCPV+zmAg7Lp4iQFqUtzZ6Rwx2xW 0M9ndGPpEqZn7pXzAMB8z05/Ut+FExhm+qvakakp8xYj7MKIc6Q9E8LjMJIR3vfwB2 UWQ3BuGGqR4exDAv8KYvtdEmcHYO4AFceSebdUDd0qTR92ymdz+ikdsbE6YzS9Lp0U ObbuXYiuxwEQMSrnEAdsuIS/ottd01HD0dFnbegyGBuPbyDqoxPPiu4juip75w+ehu CDgPk06nKRdLsWiylE/TGg6kJ/gNcoscPbmQ9nwTU0/1zhlk9WavdikrZc6sosLfzz FVskXy/SI8KTg== Message-ID: <43b5db93-1c1b-436e-a8fa-d89582e31894@kernel.org> Date: Fri, 7 Aug 2026 16:35:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] selftests/mm: fix read_file() return value check To: Hongfu Li , akpm@linux-foundation.org, ljs@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Hongfu Li References: <20260807013555.36525-1-hongfu.li@linux.dev> 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: rspam05 X-Rspamd-Queue-Id: 03FB84000A X-Rspam-User: X-Stat-Signature: 3rziopub68uycc3itsria419e7whmneg X-HE-Tag: 1786113341-346068 X-HE-Meta: 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 brvyfdab nEx76/p3/633fXCkjy0yOV964LSNdCzCEzB/5eLnvWdD5Lo8HQl1XBvjnGoaNalyPmLz4RSsGz7IxVCYH6h+1ogdoh1S4cdoY2R/utA76ex4NjMG7rMJMM2u6o8eK7ZTsPlOq6Efs0yeFdWgbVCPzr9xZZv1fUtX0dOrwH/VGN8EsP9UoPxXdypT8LxwNCI0ct6CPSTnuBhG88pvTygaYZ1fpgC8RTiyyXTncxQLSKx69u9MPBcNI8p/9d02wB5P8opVSTeYBc3g0m6TPcGDYwo5n23GYBUOMspJ4vuudHJNQaSVpD6PRF2avPlyKBGewpzl6sfPntbrrBLQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/7/26 03:35, Hongfu Li wrote: > From: Hongfu Li > > read_file() returns 0 on open/read failures and never returns negative > values. Existing < 0 error checks never trigger, so read failures are > silently ignored. Check for zero return to detect read_file() failures. > > Also fix misleading error message in get_finfo(). The error string > incorrectly references read_num when reading uevent files. > > Signed-off-by: Hongfu Li > --- > tools/testing/selftests/mm/khugepaged.c | 4 ++-- > tools/testing/selftests/mm/vm_util.c | 2 +- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c > index 10e8dedcb087..506310d4b4d5 100644 > --- a/tools/testing/selftests/mm/khugepaged.c > +++ b/tools/testing/selftests/mm/khugepaged.c > @@ -138,8 +138,8 @@ static void get_finfo(const char *dir) > major(path_stat.st_dev), minor(path_stat.st_dev)) > >= sizeof(path)) > ksft_exit_fail_msg("%s: Pathname is too long\n", __func__); > - if (read_file(path, buf, sizeof(buf)) < 0) > - ksft_exit_fail_perror("read_file(read_num)"); > + if (!read_file(path, buf, sizeof(buf))) > + ksft_exit_fail_perror("read_file(uevent)"); > if (strstr(buf, "DEVTYPE=disk")) { > /* Found it */ > if (snprintf(finfo.dev_queue_read_ahead_path, > diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c > index ef1ea11981a7..2697d50d07f4 100644 > --- a/tools/testing/selftests/mm/vm_util.c > +++ b/tools/testing/selftests/mm/vm_util.c > @@ -755,7 +755,7 @@ unsigned long read_num(const char *path) > { > char buf[21]; > > - if (read_file(path, buf, sizeof(buf)) < 0) > + if (!read_file(path, buf, sizeof(buf))) > ksft_exit_fail_perror("read_file()"); > > return strtoul(buf, NULL, 10); Yeah, that looks correct. Do we have Fixes: tags? I think it was already wrong in read_num() in commit e0c13f9761df8f97cf5e81495d12ecbc4075684a Author: Kiryl Shutsemau Date: Wed Jun 3 16:00:06 2020 -0700 khugepaged: add self test where we had + ret = read_file(path, buf, sizeof(buf)); + if (ret < 0) { + perror("read_file(read_num)"); + exit(EXIT_FAILURE); + } So likely Fixes: e0c13f9761df ("khugepaged: add self test") Acked-by: David Hildenbrand (Arm) -- Cheers, David