From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-4.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_HI,T_RP_MATCHES_RCVD autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 7024A7E66E for ; Thu, 15 Mar 2018 14:23:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752212AbeCOOVa (ORCPT ); Thu, 15 Mar 2018 10:21:30 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:42118 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751880AbeCOOV1 (ORCPT ); Thu, 15 Mar 2018 10:21:27 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8FF8B20CC6; Thu, 15 Mar 2018 14:21:26 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.34.27.30]) by smtp.corp.redhat.com (Postfix) with SMTP id 4BFDC2026E04; Thu, 15 Mar 2018 14:21:21 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Thu, 15 Mar 2018 15:21:26 +0100 (CET) Date: Thu, 15 Mar 2018 15:21:20 +0100 From: Oleg Nesterov To: Ravi Bangoria Cc: mhiramat@kernel.org, peterz@infradead.org, srikar@linux.vnet.ibm.com, 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, gregkh@linuxfoundation.org, huawei.libin@huawei.com, hughd@google.com, jack@suse.cz, jglisse@redhat.com, jolsa@redhat.com, kan.liang@intel.com, kirill.shutemov@linux.intel.com, kjlx@templeofstupid.com, kstewart@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, milian.wolff@kdab.com, mingo@redhat.com, namhyung@kernel.org, naveen.n.rao@linux.vnet.ibm.com, pc@us.ibm.com, pombredanne@nexb.com, rostedt@goodmis.org, tglx@linutronix.de, tmricht@linux.vnet.ibm.com, willy@infradead.org, yao.jin@linux.intel.com, fengguang.wu@intel.com Subject: Re: [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore) Message-ID: <20180315142120.GA19218@redhat.com> References: <20180313125603.19819-1-ravi.bangoria@linux.vnet.ibm.com> <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Thu, 15 Mar 2018 14:21:26 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Thu, 15 Mar 2018 14:21:26 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'oleg@redhat.com' RCPT:'' Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 03/13, Ravi Bangoria wrote: > > @@ -1053,6 +1056,9 @@ int uprobe_mmap(struct vm_area_struct *vma) > struct uprobe *uprobe, *u; > struct inode *inode; > > + if (uprobe_mmap_callback) > + uprobe_mmap_callback(vma); > + > if (no_uprobe_events() || !valid_vma(vma, true)) > return 0; probe_event_enable() does uprobe_register(); /* WINDOW */ sdt_increment_ref_ctr(); what if uprobe_mmap() is called in between? The counter(s) in this vma will be incremented twice, no? > +static struct vm_area_struct * > +sdt_find_vma(struct mm_struct *mm, struct trace_uprobe *tu) > +{ > + struct vm_area_struct *tmp; > + > + for (tmp = mm->mmap; tmp != NULL; tmp = tmp->vm_next) > + if (sdt_valid_vma(tu, tmp)) > + return tmp; > + > + return NULL; I can't understand the logic... Lets ignore sdt_valid_vma() for now. The caller has uprobe_map_info, why it can't simply do vma = find_vma(uprobe_map_info->vaddr)? and then check sdt_valid_vma(). Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f200.google.com (mail-qt0-f200.google.com [209.85.216.200]) by kanga.kvack.org (Postfix) with ESMTP id 1DE966B0006 for ; Thu, 15 Mar 2018 10:21:28 -0400 (EDT) Received: by mail-qt0-f200.google.com with SMTP id n51so4541755qta.9 for ; Thu, 15 Mar 2018 07:21:28 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id o63si3485347qtd.423.2018.03.15.07.21.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 15 Mar 2018 07:21:27 -0700 (PDT) Date: Thu, 15 Mar 2018 15:21:20 +0100 From: Oleg Nesterov Subject: Re: [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore) Message-ID: <20180315142120.GA19218@redhat.com> References: <20180313125603.19819-1-ravi.bangoria@linux.vnet.ibm.com> <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Ravi Bangoria Cc: mhiramat@kernel.org, peterz@infradead.org, srikar@linux.vnet.ibm.com, 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, gregkh@linuxfoundation.org, huawei.libin@huawei.com, hughd@google.com, jack@suse.cz, jglisse@redhat.com, jolsa@redhat.com, kan.liang@intel.com, kirill.shutemov@linux.intel.com, kjlx@templeofstupid.com, kstewart@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, milian.wolff@kdab.com, mingo@redhat.com, namhyung@kernel.org, naveen.n.rao@linux.vnet.ibm.com, pc@us.ibm.com, pombredanne@nexb.com, rostedt@goodmis.org, tglx@linutronix.de, tmricht@linux.vnet.ibm.com, willy@infradead.org, yao.jin@linux.intel.com, fengguang.wu@intel.com On 03/13, Ravi Bangoria wrote: > > @@ -1053,6 +1056,9 @@ int uprobe_mmap(struct vm_area_struct *vma) > struct uprobe *uprobe, *u; > struct inode *inode; > > + if (uprobe_mmap_callback) > + uprobe_mmap_callback(vma); > + > if (no_uprobe_events() || !valid_vma(vma, true)) > return 0; probe_event_enable() does uprobe_register(); /* WINDOW */ sdt_increment_ref_ctr(); what if uprobe_mmap() is called in between? The counter(s) in this vma will be incremented twice, no? > +static struct vm_area_struct * > +sdt_find_vma(struct mm_struct *mm, struct trace_uprobe *tu) > +{ > + struct vm_area_struct *tmp; > + > + for (tmp = mm->mmap; tmp != NULL; tmp = tmp->vm_next) > + if (sdt_valid_vma(tu, tmp)) > + return tmp; > + > + return NULL; I can't understand the logic... Lets ignore sdt_valid_vma() for now. The caller has uprobe_map_info, why it can't simply do vma = find_vma(uprobe_map_info->vaddr)? and then check sdt_valid_vma(). Oleg.