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 00BCF7E66E for ; Fri, 16 Mar 2018 11:39:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752031AbeCPLj0 (ORCPT ); Fri, 16 Mar 2018 07:39:26 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:54724 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751888AbeCPLjZ (ORCPT ); Fri, 16 Mar 2018 07:39:25 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B8C16EB6F9; Fri, 16 Mar 2018 11:39:24 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.34.27.30]) by smtp.corp.redhat.com (Postfix) with SMTP id 06790C1FB3; Fri, 16 Mar 2018 11:39:18 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 16 Mar 2018 12:39:24 +0100 (CET) Date: Fri, 16 Mar 2018 12:39:18 +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: <20180316113917.GA21303@redhat.com> References: <20180313125603.19819-1-ravi.bangoria@linux.vnet.ibm.com> <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com> <20180315142120.GA19218@redhat.com> <20180315143044.GA19643@redhat.com> <3b303a2d-35dd-9178-fc03-de9f2d588797@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3b303a2d-35dd-9178-fc03-de9f2d588797@linux.vnet.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Fri, 16 Mar 2018 11:39:25 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Fri, 16 Mar 2018 11:39:25 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.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 03/16, Ravi Bangoria wrote: > > On 03/15/2018 08:00 PM, Oleg Nesterov wrote: > > Note to mention that sdt_find_vma() can return NULL but the callers do > > vma_offset_to_vaddr(vma) without any check. > > If the "mm" we are passing to sdt_find_vma() is returned by > uprobe_build_map_info(ref_ctr_offset), sdt_find_vma() must > _not_ return NULL. Not at all. Once build_map_info() returns any mapping can go away. Otherwise, why do you think the caller has to take ->mmap_sem and use find_vma()? If you were right, build_map_info() could just return the list of vma's instead of list of mm's. 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