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 B8DDE7E686 for ; Thu, 15 Mar 2018 11:21:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751727AbeCOLVf (ORCPT ); Thu, 15 Mar 2018 07:21:35 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:57170 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751666AbeCOLVe (ORCPT ); Thu, 15 Mar 2018 07:21:34 -0400 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w2FBKctt125826 for ; Thu, 15 Mar 2018 07:21:33 -0400 Received: from e06smtp11.uk.ibm.com (e06smtp11.uk.ibm.com [195.75.94.107]) by mx0a-001b2d01.pphosted.com with ESMTP id 2gqmj422ap-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Thu, 15 Mar 2018 07:21:32 -0400 Received: from localhost by e06smtp11.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Thu, 15 Mar 2018 11:21:21 -0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w2FBLKGI32899232; Thu, 15 Mar 2018 11:21:20 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8F0924C044; Thu, 15 Mar 2018 11:14:34 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 832494C040; Thu, 15 Mar 2018 11:14:28 +0000 (GMT) Received: from [9.124.31.132] (unknown [9.124.31.132]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 15 Mar 2018 11:14:28 +0000 (GMT) Subject: Re: [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore) To: Oleg Nesterov 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, Ravi Bangoria References: <20180313125603.19819-1-ravi.bangoria@linux.vnet.ibm.com> <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com> <20180314165943.GA5948@redhat.com> From: Ravi Bangoria Date: Thu, 15 Mar 2018 16:53:40 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180314165943.GA5948@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18031511-0040-0000-0000-00000441150B X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18031511-0041-0000-0000-000020E41E7C Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-03-15_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1803150129 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 03/14/2018 10:29 PM, Oleg Nesterov wrote: > 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. > Hmm... I'm not quite sure. Will rethink and get back to you. > >> +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. Oops. Yes. Will change it. Thanks for the review :) Ravi -- 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