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 F22927E6C7 for ; Wed, 14 Mar 2018 17:00:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751806AbeCNQ76 (ORCPT ); Wed, 14 Mar 2018 12:59:58 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:56104 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932282AbeCNQ7v (ORCPT ); Wed, 14 Mar 2018 12:59:51 -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 962208424D; Wed, 14 Mar 2018 16:59:50 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.34.27.30]) by smtp.corp.redhat.com (Postfix) with SMTP id BFCB12026DFD; Wed, 14 Mar 2018 16:59:44 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 14 Mar 2018 17:59:50 +0100 (CET) Date: Wed, 14 Mar 2018 17:59:44 +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: <20180314165943.GA5948@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 [10.11.55.2]); Wed, 14 Mar 2018 16:59:50 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 14 Mar 2018 16:59:50 +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: > > +static bool sdt_valid_vma(struct trace_uprobe *tu, struct vm_area_struct *vma) > +{ > + unsigned long vaddr = vma_offset_to_vaddr(vma, tu->ref_ctr_offset); > + > + return tu->ref_ctr_offset && > + vma->vm_file && > + file_inode(vma->vm_file) == tu->inode && > + vma->vm_flags & VM_WRITE && > + vma->vm_start <= vaddr && > + vma->vm_end > vaddr; > +} Perhaps in this case a simple ref_ctr_offset < vma->vm_end - vma->vm_start check without vma_offset_to_vaddr() makes more sense, but I won't insist. > +static void sdt_increment_ref_ctr(struct trace_uprobe *tu) > +{ > + struct uprobe_map_info *info; > + struct vm_area_struct *vma; > + unsigned long vaddr; > + > + uprobe_start_dup_mmap(); > + info = uprobe_build_map_info(tu->inode->i_mapping, > + tu->ref_ctr_offset, false); Hmm. This doesn't look right. If you need to find all mappings (and avoid the races with fork/dup_mmap) you need to take this semaphore for writing, uprobe_start_dup_mmap() can't help. 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