From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752453AbeDIN3h (ORCPT ); Mon, 9 Apr 2018 09:29:37 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:37412 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752127AbeDIN3e (ORCPT ); Mon, 9 Apr 2018 09:29:34 -0400 Date: Mon, 9 Apr 2018 15:29:28 +0200 From: Oleg Nesterov To: Ravi Bangoria Cc: mhiramat@kernel.org, peterz@infradead.org, srikar@linux.vnet.ibm.com, rostedt@goodmis.org, acme@kernel.org, ananth@linux.vnet.ibm.com, akpm@linux-foundation.org, alexander.shishkin@linux.intel.com, alexis.berlemont@gmail.com, corbet@lwn.net, dan.j.williams@intel.com, jolsa@redhat.com, kan.liang@intel.com, kjlx@templeofstupid.com, kstewart@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, milian.wolff@kdab.com, mingo@redhat.com, namhyung@kernel.org, naveen.n.rao@linux.vnet.ibm.com, pc@us.ibm.com, tglx@linutronix.de, yao.jin@linux.intel.com, fengguang.wu@intel.com, jglisse@redhat.com Subject: Re: [PATCH v2 7/9] trace_uprobe/sdt: Fix multiple update of same reference counter Message-ID: <20180409132928.GA25722@redhat.com> References: <20180404083110.18647-1-ravi.bangoria@linux.vnet.ibm.com> <20180404083110.18647-8-ravi.bangoria@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180404083110.18647-8-ravi.bangoria@linux.vnet.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/04, Ravi Bangoria wrote: > > +static void sdt_add_mm_list(struct trace_uprobe *tu, struct mm_struct *mm) > +{ > + struct mmu_notifier *mn; > + struct sdt_mm_list *sml = kzalloc(sizeof(*sml), GFP_KERNEL); > + > + if (!sml) > + return; > + sml->mm = mm; > + list_add(&(sml->list), &(tu->sml.list)); > + > + /* Register mmu_notifier for this mm. */ > + mn = kzalloc(sizeof(*mn), GFP_KERNEL); > + if (!mn) > + return; > + > + mn->ops = &sdt_mmu_notifier_ops; > + __mmu_notifier_register(mn, mm); > +} and what if __mmu_notifier_register() fails simply because signal_pending() == T? see mm_take_all_locks(). at first glance this all look suspicious and sub-optimal, but let me repeat that I didn't read this version yet. Oleg.