From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754543Ab2G3OOW (ORCPT ); Mon, 30 Jul 2012 10:14:22 -0400 Received: from terminus.zytor.com ([198.137.202.10]:45595 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754446Ab2G3OOV (ORCPT ); Mon, 30 Jul 2012 10:14:21 -0400 Date: Mon, 30 Jul 2012 07:14:04 -0700 From: tip-bot for Oleg Nesterov Message-ID: Cc: linux-kernel@vger.kernel.org, anton@redhat.com, hpa@zytor.com, mingo@kernel.org, srikar@linux.vnet.ibm.com, oleg@redhat.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, anton@redhat.com, linux-kernel@vger.kernel.org, srikar@linux.vnet.ibm.com, tglx@linutronix.de, oleg@redhat.com In-Reply-To: <20120729182231.GA20336@redhat.com> References: <20120729182231.GA20336@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] uprobes: Suppress uprobe_munmap() from mmput() Git-Commit-ID: 2fd611a991391a6050cbd139201a2e12fc306540 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-4.2.6 (terminus.zytor.com [127.0.0.1]); Mon, 30 Jul 2012 07:14:10 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 2fd611a991391a6050cbd139201a2e12fc306540 Gitweb: http://git.kernel.org/tip/2fd611a991391a6050cbd139201a2e12fc306540 Author: Oleg Nesterov AuthorDate: Sun, 29 Jul 2012 20:22:31 +0200 Committer: Ingo Molnar CommitDate: Mon, 30 Jul 2012 11:27:21 +0200 uprobes: Suppress uprobe_munmap() from mmput() uprobe_munmap() does get_user_pages() and it is also called from the final mmput()->exit_mmap() path. This slows down exit/mmput() for no reason, and I think it is simply dangerous/wrong to try to fault-in a page into the dying mm. If nothing else, this happens after the last sync_mm_rss(), afaics handle_mm_fault() can change the task->rss_stat and make the subsequent check_mm() unhappy. Change uprobe_munmap() to check mm->mm_users != 0. Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju Cc: Anton Arapov Cc: Srikar Dronamraju Link: http://lkml.kernel.org/r/20120729182231.GA20336@redhat.com Signed-off-by: Ingo Molnar --- kernel/events/uprobes.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index bed2161..9db9cdf 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1082,6 +1082,9 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) return; + if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ + return; + if (!atomic_read(&vma->vm_mm->uprobes_state.count)) return;