From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757932Ab3J2OIy (ORCPT ); Tue, 29 Oct 2013 10:08:54 -0400 Received: from terminus.zytor.com ([198.137.202.10]:45930 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757793Ab3J2OIv (ORCPT ); Tue, 29 Oct 2013 10:08:51 -0400 Date: Tue, 29 Oct 2013 07:08:16 -0700 From: tip-bot for Oleg Nesterov Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, oleg@redhat.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, tglx@linutronix.de, oleg@redhat.com In-Reply-To: <20131016201004.GC23214@redhat.com> References: <20131016201004.GC23214@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] perf: Do not waste PAGE_SIZE bytes for ALIGN(8) in perf_event_mmap_event() Git-Commit-ID: 3ea2f2b96f9e636f49eb10962e96db3e19cab157 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.1 (terminus.zytor.com [127.0.0.1]); Tue, 29 Oct 2013 07:08:22 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 3ea2f2b96f9e636f49eb10962e96db3e19cab157 Gitweb: http://git.kernel.org/tip/3ea2f2b96f9e636f49eb10962e96db3e19cab157 Author: Oleg Nesterov AuthorDate: Wed, 16 Oct 2013 22:10:04 +0200 Committer: Ingo Molnar CommitDate: Tue, 29 Oct 2013 12:02:52 +0100 perf: Do not waste PAGE_SIZE bytes for ALIGN(8) in perf_event_mmap_event() perf_event_mmap_event() does kzalloc(PATH_MAX + sizeof(u64)) to ensure we can align the size later. However this means that we actually allocate PAGE_SIZE * 2 buffer, seems too much. Change this code to allocate PATH_MAX==PAGE_SIZE bytes, but tell d_path() to not use the last sizeof(u64) bytes. Note: it is not clear why do we need __GFP_ZERO, see the next patch. Signed-off-by: Oleg Nesterov Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20131016201004.GC23214@redhat.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 3ea5605..b409e75 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5113,17 +5113,18 @@ static void perf_event_mmap_event(struct perf_mmap_event *mmap_event) if (file) { struct inode *inode; dev_t dev; - /* - * d_path works from the end of the rb backwards, so we - * need to add enough zero bytes after the string to handle - * the 64bit alignment we do later. - */ - buf = kzalloc(PATH_MAX + sizeof(u64), GFP_KERNEL); + + buf = kzalloc(PATH_MAX, GFP_KERNEL); if (!buf) { name = strncpy(tmp, "//enomem", sizeof(tmp)); goto got_name; } - name = d_path(&file->f_path, buf, PATH_MAX); + /* + * d_path() works from the end of the rb backwards, so we + * need to add enough zero bytes after the string to handle + * the 64bit alignment we do later. + */ + name = d_path(&file->f_path, buf, PATH_MAX - sizeof(u64)); if (IS_ERR(name)) { name = strncpy(tmp, "//toolong", sizeof(tmp)); goto got_name;