From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f70.google.com (mail-pl0-f70.google.com [209.85.160.70]) by kanga.kvack.org (Postfix) with ESMTP id 110066B0006 for ; Thu, 15 Mar 2018 12:48:22 -0400 (EDT) Received: by mail-pl0-f70.google.com with SMTP id t10-v6so3129926plr.12 for ; Thu, 15 Mar 2018 09:48:22 -0700 (PDT) Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id x190si3677873pgx.159.2018.03.15.09.48.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 15 Mar 2018 09:48:21 -0700 (PDT) Date: Thu, 15 Mar 2018 12:48:16 -0400 From: Steven Rostedt Subject: Re: [PATCH 5/8] trace_uprobe: Support SDT markers having reference count (semaphore) Message-ID: <20180315124816.6aa3d4e2@vmware.local.home> In-Reply-To: <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.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-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Ravi Bangoria Cc: mhiramat@kernel.org, oleg@redhat.com, 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, tglx@linutronix.de, tmricht@linux.vnet.ibm.com, willy@infradead.org, yao.jin@linux.intel.com, fengguang.wu@intel.com On Tue, 13 Mar 2018 18:26:00 +0530 Ravi Bangoria wrote: > +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(); Please add a comment here that this function ups the mm ref count for each info returned. Otherwise it's hard to know what that mmput() below matches. -- Steve > + info = uprobe_build_map_info(tu->inode->i_mapping, > + tu->ref_ctr_offset, false); > + if (IS_ERR(info)) > + goto out; > + > + while (info) { > + down_write(&info->mm->mmap_sem); > + > + vma = sdt_find_vma(info->mm, tu); > + vaddr = vma_offset_to_vaddr(vma, tu->ref_ctr_offset); > + sdt_update_ref_ctr(info->mm, vaddr, 1); > + > + up_write(&info->mm->mmap_sem); > + mmput(info->mm); > + info = uprobe_free_map_info(info); > + } > + > +out: > + uprobe_end_dup_mmap(); > +} > +