From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELuQ7lOidavcwqM4OSwrVCCPpRoHGn2mAZsCqpwPnTzPLWi4FOMlI0B8I/ucp/Gj0D15A2LE ARC-Seal: i=1; a=rsa-sha256; t=1521112893; cv=none; d=google.com; s=arc-20160816; b=0/DqcCj+R4Jnf+R/r7ib/p90rOtex3eNfdM2i+a5T0asd1QxrXCeXuQg/19tU4Ymh6 s47U3cywIm/54YhUKyd2jDZhY0g6jiPXt6CZms+yuz9DaXRzqsYWyg0qFJq7JzXHr7ro S3ApDVS1cD/PybFM7BjvBflstz+SLHpjocfyYfrG7pbX3RXXX++EiMI6BkoXyTtTuxde 6VMOEzxNO+Y1OUIs/A1xx91u9QcrY/5shmz16IS/VOkyGF5CRKdo0rwEDC3iS+T/iq7y 1tvxJzh8UBB+RF3MghgL0KKSEjIvYySGYmwof0jsAT2bIdXnXAuiTiXERdEbwQjjx8Tm PxHA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:content-language:content-transfer-encoding:in-reply-to :mime-version:user-agent:date:from:references:cc:to:subject :arc-authentication-results; bh=fVqZjI9uQGp3pYO5Wztmznk1dYYb5lTMEqJMnAnByrg=; b=Y0Ca89yvZerdZlj11jJkseZyLVDorFSeCcA3RRAkEt23zujC+3FFCyM6Q+AaSP9fgR izTxbn6V2iB5GUFI7cjN53qfeFd0N7NUnwJbxfNrYXe/X8+c+ywoCMojHXrSscpJ7KVj 6KQG/+ZjkC5+DyaHcnBHoge8Djl2fovdA7ro6lcSgwdwNDXSuBCFd2Krc7V1J71sgqwp uP1pz82F60jqlbWFFhok22VsiHlVzxBwAUvS0CaaEXFFyUtphZdq5trMgCzXpxY7DDOA Diz2snmi5ZNz32QvOk4fF7Q1KyJl9nBufeWAKpJDF50Xq4GSE4x4z0WUNW+x0o3OPThL NFKA== ARC-Authentication-Results: i=1; mx.google.com; spf=neutral (google.com: 148.163.158.5 is neither permitted nor denied by best guess record for domain of ravi.bangoria@linux.vnet.ibm.com) smtp.mailfrom=ravi.bangoria@linux.vnet.ibm.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=ibm.com Authentication-Results: mx.google.com; spf=neutral (google.com: 148.163.158.5 is neither permitted nor denied by best guess record for domain of ravi.bangoria@linux.vnet.ibm.com) smtp.mailfrom=ravi.bangoria@linux.vnet.ibm.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=ibm.com 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 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594827101403620100?= X-GMAIL-MSGID: =?utf-8?q?1595002473678810030?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 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