From nobody Mon Mar 23 21:23:18 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 029E93C945D for ; Mon, 23 Mar 2026 15:18:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774279122; cv=none; b=DIcbOqH/bhx3WWqtZ9DBd1uSqJNw+vNEcgB10u+U51rhKMO2In5f+1v9ym07nXJTma3NWpZw92XY9/zJ1S3QvCYan2uFFmwEoduEa263O6WiWSKNBne4Uqw2BflLLRABloilLAPhMwK0SvFw6acb/PD0UmjVMD+Ifb2LLlDVhww= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774279122; c=relaxed/simple; bh=Ld61DTphqrcs7C1Ha7+CpC6LPIRHZtWmxHj+OAybMWE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JTktXmF9zBmn5rddn/X6/04b+nCsLakwNglD+skg8Esp8qtmd6IIu3swngzD8sq+4EVCkLdGrCNk0o0Ngy/8VIcyZ5gG425hMHsQ82t3xU3P3M7KWbtTt72fkyzYcRqe15WSgKGF3ykCOKzhvLszF6Q9Nijk7SYNIgZujTEQIeE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=IKywzNz/; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IKywzNz/" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1774279119; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9yceaFKZVBDF6JEZ2vLeDlRB6dW1GshHGmSjH6pnVzE=; b=IKywzNz/ond0PzMrxThZGqTNTbCNrltgpiZnfTNbROXq0v10Vr1YpykYdVJ4pia9jFEawo boWPkUxhWqxB9K4+ROF5WqHJetUYHCrzz1aPBDD3kTwQE50mdt5HF8dL8t+XtjarcMCJ3y syM2J1X+FMWy1TlbU34yA3vatnDCf1g= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-466-xBrg_OwWNa2nq4sZM98mmw-1; Mon, 23 Mar 2026 11:18:36 -0400 X-MC-Unique: xBrg_OwWNa2nq4sZM98mmw-1 X-Mimecast-MFC-AGG-ID: xBrg_OwWNa2nq4sZM98mmw_1774279114 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E084919560A1; Mon, 23 Mar 2026 15:18:33 +0000 (UTC) Received: from dell-per7425-02.rhts.eng.pek2.redhat.com (dell-per7425-02.rhts.eng.pek2.redhat.com [10.73.116.18]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 13DD71955D71; Mon, 23 Mar 2026 15:18:25 +0000 (UTC) From: Chunyu Hu To: akpm@linux-foundation.org, david@kernel.org, shuah@kernel.org, linux-mm@kvack.org, ljs@kernel.org Cc: linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, chuhu@redhat.com Subject: [PATCH v5 3/6] selftests/mm: move write_file helper to vm_util Date: Mon, 23 Mar 2026 23:17:50 +0800 Message-ID: <20260323151753.2576137-4-chuhu@redhat.com> In-Reply-To: <20260323151753.2576137-1-chuhu@redhat.com> References: <20260323151753.2576137-1-chuhu@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Content-Type: text/plain; charset="utf-8" thp_settings provides write_file() helper for safely writing to a file and exit when write failure happens. It's a very low level helper and many sub tests need such a helper, not only thp tests. split_huge_page_test also defines a write_file locally. The two have minior differences in return type and used exit api. And there would be conflicts if split_huge_page_test wanted to include thp_settings.h because of different prototype, making it less convenient. It's possisble to merge the two, although some tests don't use the kselftest infrastrucutre for testing. It would also work when using the ksft_exit_msg() to exit in my test, as the counters are all zero. Output will be like: TAP version 13 1..62 Bail out! /proc/sys/vm/drop_caches1 open failed: No such file or directory # Totals: pass:0 fail:0 xfail:0 xpass:0 skip:0 error:0 So here we just keep the version in split_huge_page_test, and move it into the vm_util. This makes it easy to maitain and user could just include one vm_util.h when they don't need thp setting helpers. Keep the prototype of void return as the function will exit on any error, return value is not necessary, and will simply the callers like write_num() and write_string(). Acked-by: David Hildenbrand (Arm) Reviewed-by: Zi Yan Acked-by: Mike Rapoport (Microsoft) Suggested-by: Mike Rapoport Signed-off-by: Chunyu Hu --- Changes in v5: - updated acked-by and reviewed-by Changes in v3: - make the write_file void return Changes in v2: new patch from v2 --- .../selftests/mm/split_huge_page_test.c | 15 -------- tools/testing/selftests/mm/thp_settings.c | 35 ++----------------- tools/testing/selftests/mm/thp_settings.h | 1 - tools/testing/selftests/mm/vm_util.c | 15 ++++++++ tools/testing/selftests/mm/vm_util.h | 2 ++ 5 files changed, 20 insertions(+), 48 deletions(-) diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/test= ing/selftests/mm/split_huge_page_test.c index e0167111bdd1..93f205327b84 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -255,21 +255,6 @@ static int check_after_split_folio_orders(char *vaddr_= start, size_t len, return status; } =20 -static void write_file(const char *path, const char *buf, size_t buflen) -{ - int fd; - ssize_t numwritten; - - fd =3D open(path, O_WRONLY); - if (fd =3D=3D -1) - ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno)); - - numwritten =3D write(fd, buf, buflen - 1); - close(fd); - if (numwritten < 1) - ksft_exit_fail_msg("Write failed\n"); -} - static void write_debugfs(const char *fmt, ...) { char input[INPUT_MAX]; diff --git a/tools/testing/selftests/mm/thp_settings.c b/tools/testing/self= tests/mm/thp_settings.c index 574bd0f8ae48..e748ebfb3d4e 100644 --- a/tools/testing/selftests/mm/thp_settings.c +++ b/tools/testing/selftests/mm/thp_settings.c @@ -6,6 +6,7 @@ #include #include =20 +#include "vm_util.h" #include "thp_settings.h" =20 #define THP_SYSFS "/sys/kernel/mm/transparent_hugepage/" @@ -64,29 +65,6 @@ int read_file(const char *path, char *buf, size_t buflen) return (unsigned int) numread; } =20 -int write_file(const char *path, const char *buf, size_t buflen) -{ - int fd; - ssize_t numwritten; - - fd =3D open(path, O_WRONLY); - if (fd =3D=3D -1) { - printf("open(%s)\n", path); - exit(EXIT_FAILURE); - return 0; - } - - numwritten =3D write(fd, buf, buflen - 1); - close(fd); - if (numwritten < 1) { - printf("write(%s)\n", buf); - exit(EXIT_FAILURE); - return 0; - } - - return (unsigned int) numwritten; -} - unsigned long read_num(const char *path) { char buf[21]; @@ -104,10 +82,7 @@ void write_num(const char *path, unsigned long num) char buf[21]; =20 sprintf(buf, "%ld", num); - if (!write_file(path, buf, strlen(buf) + 1)) { - perror(path); - exit(EXIT_FAILURE); - } + write_file(path, buf, strlen(buf) + 1); } =20 int thp_read_string(const char *name, const char * const strings[]) @@ -165,11 +140,7 @@ void thp_write_string(const char *name, const char *va= l) printf("%s: Pathname is too long\n", __func__); exit(EXIT_FAILURE); } - - if (!write_file(path, val, strlen(val) + 1)) { - perror(path); - exit(EXIT_FAILURE); - } + write_file(path, val, strlen(val) + 1); } =20 unsigned long thp_read_num(const char *name) diff --git a/tools/testing/selftests/mm/thp_settings.h b/tools/testing/self= tests/mm/thp_settings.h index 76eeb712e5f1..7748a9009191 100644 --- a/tools/testing/selftests/mm/thp_settings.h +++ b/tools/testing/selftests/mm/thp_settings.h @@ -63,7 +63,6 @@ struct thp_settings { }; =20 int read_file(const char *path, char *buf, size_t buflen); -int write_file(const char *path, const char *buf, size_t buflen); unsigned long read_num(const char *path); void write_num(const char *path, unsigned long num); =20 diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests= /mm/vm_util.c index a6d4ff7dfdc0..ad96d19d1b85 100644 --- a/tools/testing/selftests/mm/vm_util.c +++ b/tools/testing/selftests/mm/vm_util.c @@ -764,3 +764,18 @@ int unpoison_memory(unsigned long pfn) =20 return ret > 0 ? 0 : -errno; } + +void write_file(const char *path, const char *buf, size_t buflen) +{ + int fd; + ssize_t numwritten; + + fd =3D open(path, O_WRONLY); + if (fd =3D=3D -1) + ksft_exit_fail_msg("%s open failed: %s\n", path, strerror(errno)); + + numwritten =3D write(fd, buf, buflen - 1); + close(fd); + if (numwritten < 1) + ksft_exit_fail_msg("Write failed\n"); +} diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests= /mm/vm_util.h index e9c4e24769c1..1a07305ceff4 100644 --- a/tools/testing/selftests/mm/vm_util.h +++ b/tools/testing/selftests/mm/vm_util.h @@ -166,3 +166,5 @@ int unpoison_memory(unsigned long pfn); =20 #define PAGEMAP_PRESENT(ent) (((ent) & (1ull << 63)) !=3D 0) #define PAGEMAP_PFN(ent) ((ent) & ((1ull << 55) - 1)) + +void write_file(const char *path, const char *buf, size_t buflen); --=20 2.53.0