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 5EF0D38E8C3; Fri, 7 Aug 2026 14:35:41 +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=1786113342; cv=none; b=rgMsrjOoxuwgC72vKZ/LknQ6uZ7jf+JR/hLBgirYZJh29C2ij9CupHgNQZE1ByOGVURaxvZpWRozOj7znzR8ryw68ZlARqOmWR8biRkBXhISq3FU9peqeQxjdlnVSGY0yF2TBGTiR97WtnySAzrlgIuCFzc+OE8tarbXFRnHnn8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786113342; c=relaxed/simple; bh=kRuxVW5nMI+o4h4F4RtkT03d1/YymNsIxIQq/gLwewA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=sCpGhJ66dlMad8kMEALdRlUGna3uy86nBJYfehsm+HTlx79WIsUUJ6Zz6Kp4LLePbQhaqYLoNyxMZaDwTKZC7ZFQqJVKYGrUONFThT7jL59K3b9ONPOsT6oFhsH1anrZbK74jGJq48w30msl1vO/S9392Qq374VBs/Yc3avWrvU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cO4jAMG2; 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="cO4jAMG2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D57D1F000E9; Fri, 7 Aug 2026 14:35:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786113341; bh=SiconhQnpjAKJhJrHS8zmboQaF7/KkpqRkwt9AKBFKM=; h=Date:Subject:To:Cc:References:From:In-Reply-To; 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 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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