Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756073AbYJNHFf (ORCPT ); Tue, 14 Oct 2008 03:05:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752445AbYJNHFZ (ORCPT ); Tue, 14 Oct 2008 03:05:25 -0400 Received: from courier.cs.helsinki.fi ([128.214.9.1]:52308 "EHLO mail.cs.helsinki.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751903AbYJNHFY (ORCPT ); Tue, 14 Oct 2008 03:05:24 -0400 Subject: Re: [PROBLEM] hard-lock with kmemtrace, relayfs, and splice From: Pekka Enberg To: Tom Zanussi Cc: Eduard - Gabriel Munteanu , jens.axboe@oracle.com, linux-kernel@vger.kernel.org In-Reply-To: <48F42A93.1040004@cs.helsinki.fi> References: <20080923212914.GB5237@localhost> <1223386477.28348.42.camel@penberg-laptop> <1223623191.8959.26.camel@penberg-laptop> <1223628687.8959.37.camel@penberg-laptop> <1223629803.8959.40.camel@penberg-laptop> <1223631723.8959.46.camel@penberg-laptop> <1223701131.7489.25.camel@charm-linux> <1223881068.31587.1.camel@penberg-laptop> <1223957031.10883.7.camel@charm-linux> <48F42A93.1040004@cs.helsinki.fi> Date: Tue, 14 Oct 2008 10:05:30 +0300 Message-Id: <1223967930.18017.2.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit X-Mailer: Evolution 2.22.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2103 Lines: 64 On Tue, 2008-10-14 at 08:13 +0300, Pekka Enberg wrote: > Hi Tom, > > Tom Zanussi wrote: > > To me, that sounds like how it should work - if kmemtrace is disabled, > > it shouldn't be logging anything, and that's in fact what I saw when > > debugging this - it started out disabled and therefore nothing being > > logged to relay (printks confirmed that). When I wrote 1 to the enabled > > file, data started getting logged to relay and to the *.out files. > > > > So I don't know why the enabled state behaves the way it does, or if > > it's unexpected, but that anyway doesn't seem like a relay problem to > > me. > > Oh, right. Looking at kmemtraced.c, we never enable kmemtrace, just > disable it (which doesn't make much sense). Bug in README or the code. Eduard, here's a fix for the userspace counterpart: >From aa95e997458fd4d2a3b9a5c75e1452e22a3159af Mon Sep 17 00:00:00 2001 From: Pekka Enberg Date: Tue, 14 Oct 2008 10:03:51 +0300 Subject: [PATCH] kmemtrace: enable tracing in kmemtraced If kmemtrace is not enabled at boot, we need to enable it before we start relaying data to userspace. Signed-off-by: Pekka Enberg --- kmemtraced.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kmemtraced.c b/kmemtraced.c index 217478d..5cc1ada 100644 --- a/kmemtraced.c +++ b/kmemtraced.c @@ -165,8 +165,6 @@ int main(int argc, char *argv[]) if (!readers) panic("Out of memory!\n"); - write_str("/sys/kernel/debug/kmemtrace/enabled", "0"); - printf("Copying /proc/kallsyms...\n"); copy_kallsyms(); @@ -180,6 +178,8 @@ int main(int argc, char *argv[]) strerror(errno)); } + write_str("/sys/kernel/debug/kmemtrace/enabled", "1"); + printf("Logging... Press Control-C to stop.\n"); while (sigwait(&signals, &signal) == 0) { -- 1.5.4.3 -- 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/