From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756664AbZBIS0j (ORCPT ); Mon, 9 Feb 2009 13:26:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753619AbZBIS0b (ORCPT ); Mon, 9 Feb 2009 13:26:31 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:50047 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751891AbZBIS0a (ORCPT ); Mon, 9 Feb 2009 13:26:30 -0500 Subject: [PATCH] futex: fix reference leak From: Peter Zijlstra To: Catalin Marinas Cc: linux-kernel , Andrew Morton , Darren Hart , Thomas Gleixner , Ingo Molnar , "Pallipadi, Venkatesh" In-Reply-To: <1234200538.16083.52.camel@pc1117.cambridge.arm.com> References: <1234181898.16083.26.camel@pc1117.cambridge.arm.com> <1234190649.16083.44.camel@pc1117.cambridge.arm.com> <1234192363.5951.129.camel@laptop> <1234197950.5951.132.camel@laptop> <1234198023.5951.133.camel@laptop> <1234200538.16083.52.camel@pc1117.cambridge.arm.com> Content-Type: text/plain Date: Mon, 09 Feb 2009 19:26:15 +0100 Message-Id: <1234203975.5951.143.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.25.90 Content-Transfer-Encoding: 7bit X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Venki, does this perchance solve your issue with my futex patch? Darren, could you please have a look at this before Ingo pushes it out to Linus? --- Catalin noticed that (38d47c1b7075: futex: rely on get_user_pages() for shared futexes) caused an mm_struct leak. Some tracing with the function graph tracer quickly pointed out that futex_wait() has exit paths with unbalanced reference counts. Signed-off-by: Peter Zijlstra --- kernel/futex.c | 23 +++++++++++++++-------- 1 files changed, 15 insertions(+), 8 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index f89d373..7b76c8e 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1284,18 +1284,23 @@ retry: */ /* If we were woken (and unqueued), we succeeded, whatever. */ - if (!unqueue_me(&q)) - return 0; - if (rem) - return -ETIMEDOUT; + if (!unqueue_me(&q)) { + ret = 0; + goto out_put_key; + } + if (rem) { + ret = -ETIMEDOUT; + goto out_put_key; + } /* * We expect signal_pending(current), but another thread may * have handled it for us already. */ - if (!abs_time) - return -ERESTARTSYS; - else { + if (!abs_time) { + ret = -ERESTARTSYS; + goto out_put_key; + } else { struct restart_block *restart; restart = ¤t_thread_info()->restart_block; restart->fn = futex_wait_restart; @@ -1309,11 +1314,13 @@ retry: restart->futex.flags |= FLAGS_SHARED; if (clockrt) restart->futex.flags |= FLAGS_CLOCKRT; - return -ERESTART_RESTARTBLOCK; + ret = -RESTART_RESTARTBLOCK; + goto out_put_key; } out_unlock_put_key: queue_unlock(&q, hb); +out_put_key: put_futex_key(fshared, &q.key); out: