From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42AD3ECDFB8 for ; Tue, 24 Jul 2018 03:35:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 07F1220874 for ; Tue, 24 Jul 2018 03:35:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 07F1220874 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388293AbeGXEjT (ORCPT ); Tue, 24 Jul 2018 00:39:19 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:34070 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2388107AbeGXEjT (ORCPT ); Tue, 24 Jul 2018 00:39:19 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w6O3Y7Xa194557 for ; Mon, 23 Jul 2018 23:34:57 -0400 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0b-001b2d01.pphosted.com with ESMTP id 2kdqff1am0-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 23 Jul 2018 23:34:57 -0400 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Tue, 24 Jul 2018 04:34:51 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w6O3YopF41222270 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 24 Jul 2018 03:34:50 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1593FAE055; Tue, 24 Jul 2018 06:35:00 +0100 (BST) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2DC17AE045; Tue, 24 Jul 2018 06:34:57 +0100 (BST) Received: from [9.124.31.70] (unknown [9.124.31.70]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 24 Jul 2018 06:34:57 +0100 (BST) Subject: Re: [PATCH v6 3/6] Uprobes: Support SDT markers having reference count (semaphore) To: Oleg Nesterov Cc: srikar@linux.vnet.ibm.com, rostedt@goodmis.org, mhiramat@kernel.org, peterz@infradead.org, mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, linux-kernel@vger.kernel.org, ananth@linux.vnet.ibm.com, alexis.berlemont@gmail.com, naveen.n.rao@linux.vnet.ibm.com, linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org, linux@armlinux.org.uk, ralf@linux-mips.org, paul.burton@mips.com, Ravi Bangoria References: <20180716084706.28244-1-ravi.bangoria@linux.ibm.com> <20180716084706.28244-4-ravi.bangoria@linux.ibm.com> <20180723162629.GA8584@redhat.com> From: Ravi Bangoria Date: Tue, 24 Jul 2018 09:04:47 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180723162629.GA8584@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18072403-0012-0000-0000-0000028DDCE5 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18072403-0013-0000-0000-000020BFBBBF Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-07-24_01:,, 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 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1806210000 definitions=main-1807240036 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Oleg, On 07/23/2018 09:56 PM, Oleg Nesterov wrote: > I have a mixed feeling about this series... I'll try to summarise my thinking > tomorrow, but I do not see any obvious problem so far. Although I have some > concerns about 5/6, I need to re-read it after sleep. Sure. > > > On 07/16, Ravi Bangoria wrote: >> >> +static int delayed_uprobe_install(struct vm_area_struct *vma) >> +{ >> + struct list_head *pos, *q; >> + struct delayed_uprobe *du; >> + unsigned long vaddr; >> + int ret = 0, err = 0; >> + >> + mutex_lock(&delayed_uprobe_lock); >> + list_for_each_safe(pos, q, &delayed_uprobe_list) { >> + du = list_entry(pos, struct delayed_uprobe, list); >> + >> + if (!du->uprobe->ref_ctr_offset || > > Is it possible to see ->ref_ctr_offset == 0 in delayed_uprobe_list? I'll remove this check. > >> @@ -1072,7 +1282,13 @@ int uprobe_mmap(struct vm_area_struct *vma) >> struct uprobe *uprobe, *u; >> struct inode *inode; >> >> - if (no_uprobe_events() || !valid_vma(vma, true)) >> + if (no_uprobe_events()) >> + return 0; >> + >> + if (vma->vm_flags & VM_WRITE) >> + delayed_uprobe_install(vma); > > Obviously not nice performance-wise... OK, I do not know if it will actually > hurt in practice and probably we can use the better data structures if necessary. > But can't we check MMF_HAS_UPROBES at least? I mean, > > if (vma->vm_flags & VM_WRITE && test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags)) > delayed_uprobe_install(vma); > > ? Yes. > > > Perhaps we can even add another flag later, MMF_HAS_DELAYED_UPROBES set by > delayed_uprobe_add(). Yes, good idea. Thanks for the review, Ravi From mboxrd@z Thu Jan 1 00:00:00 1970 From: ravi.bangoria@linux.ibm.com (Ravi Bangoria) Date: Tue, 24 Jul 2018 09:04:47 +0530 Subject: [PATCH v6 3/6] Uprobes: Support SDT markers having reference count (semaphore) In-Reply-To: <20180723162629.GA8584@redhat.com> References: <20180716084706.28244-1-ravi.bangoria@linux.ibm.com> <20180716084706.28244-4-ravi.bangoria@linux.ibm.com> <20180723162629.GA8584@redhat.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Oleg, On 07/23/2018 09:56 PM, Oleg Nesterov wrote: > I have a mixed feeling about this series... I'll try to summarise my thinking > tomorrow, but I do not see any obvious problem so far. Although I have some > concerns about 5/6, I need to re-read it after sleep. Sure. > > > On 07/16, Ravi Bangoria wrote: >> >> +static int delayed_uprobe_install(struct vm_area_struct *vma) >> +{ >> + struct list_head *pos, *q; >> + struct delayed_uprobe *du; >> + unsigned long vaddr; >> + int ret = 0, err = 0; >> + >> + mutex_lock(&delayed_uprobe_lock); >> + list_for_each_safe(pos, q, &delayed_uprobe_list) { >> + du = list_entry(pos, struct delayed_uprobe, list); >> + >> + if (!du->uprobe->ref_ctr_offset || > > Is it possible to see ->ref_ctr_offset == 0 in delayed_uprobe_list? I'll remove this check. > >> @@ -1072,7 +1282,13 @@ int uprobe_mmap(struct vm_area_struct *vma) >> struct uprobe *uprobe, *u; >> struct inode *inode; >> >> - if (no_uprobe_events() || !valid_vma(vma, true)) >> + if (no_uprobe_events()) >> + return 0; >> + >> + if (vma->vm_flags & VM_WRITE) >> + delayed_uprobe_install(vma); > > Obviously not nice performance-wise... OK, I do not know if it will actually > hurt in practice and probably we can use the better data structures if necessary. > But can't we check MMF_HAS_UPROBES at least? I mean, > > if (vma->vm_flags & VM_WRITE && test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags)) > delayed_uprobe_install(vma); > > ? Yes. > > > Perhaps we can even add another flag later, MMF_HAS_DELAYED_UPROBES set by > delayed_uprobe_add(). Yes, good idea. Thanks for the review, Ravi