Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756799Ab1DLOhb (ORCPT ); Tue, 12 Apr 2011 10:37:31 -0400 Received: from kroah.org ([198.145.64.141]:57347 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756637Ab1DLOh3 (ORCPT ); Tue, 12 Apr 2011 10:37:29 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Tue Apr 12 07:35:48 2011 Message-Id: <20110412143548.450281756@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Tue, 12 Apr 2011 07:33:54 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Frederic Weisbecker , Arnaldo Carvalho de Melo , Stephane Eranian , Ingo Molnar Subject: [005/105] perf: Better fit max unprivileged mlock pages for tools needs In-Reply-To: <20110412143613.GA19478@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2235 Lines: 61 2.6.38-stable review patch. If anyone has any objections, please let us know. ------------------ From: Frederic Weisbecker commit 880f57318450dbead6a03f9e31a1468924d6dd88 upstream. The maximum kilobytes of locked memory that an unprivileged user can reserve is of 512 kB = 128 pages by default, scaled to the number of onlined CPUs, which fits well with the tools that use 128 data pages by default. However tools actually use 129 pages, because they need one more for the user control page. Thus the default mlock threshold is not sufficient for the default tools needs and we always end up to evaluate the constant mlock rlimit policy, which doesn't have this scaling with the number of online CPUs. Hence, on systems that have more than 16 CPUs, we overlap the rlimit threshold and fail to mmap: $ perf record ls Error: failed to mmap with 1 (Operation not permitted) Just increase the max unprivileged mlock threshold by one page so that it supports well perf tools even after 16 CPUs. Reported-by: Han Pingtian Reported-by: Peter Zijlstra Reported-by: Arnaldo Carvalho de Melo Signed-off-by: Frederic Weisbecker Acked-by: Arnaldo Carvalho de Melo Cc: Stephane Eranian LKML-Reference: <1300904979-5508-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/perf_event.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -62,7 +62,8 @@ static struct srcu_struct pmus_srcu; */ int sysctl_perf_event_paranoid __read_mostly = 1; -int sysctl_perf_event_mlock __read_mostly = 512; /* 'free' kb per user */ +/* Minimum for 128 pages + 1 for the user control page */ +int sysctl_perf_event_mlock __read_mostly = 516; /* 'free' kb per user */ /* * max perf event sample rate -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/