From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELv6RocNDMNGW7Wf+njikJpCli5NfftZ9EESPWQ4cVOY2p5LlPWJKNAqVbPnwOFm9KXgnQcR ARC-Seal: i=1; a=rsa-sha256; t=1521200366; cv=none; d=google.com; s=arc-20160816; b=JDbf4hBjZFob/nG7GzWrQASoLdeJ1HGnGujmhkmhpn4yTgWKgORwBio8f2Cfqbi61D ErS53GzAMChx/yYkTzwPQXD4it7SoccXCGbxRLhkd51xj8HotOo6J8UnCJRoO2ca7EKm pinQtrwsgraXlbVinw1gJGxdS2ihAZOaNL5GsWoe5znirbCH1T7omD+qd/+fiZX4sYdG I9EemKVekHyW0Y6tC89wrd6390OWaiMGV/lImacXwgYNgGy0F2LCEDN8ushUD/gWgIC1 LisSR3mDUWSwckc3cWjoeAuEAfyzwytNL8nJp70JXKgdeHMZWp/95U9msK1oqdNNT/2w ubFg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:arc-authentication-results; bh=GdMnHymNFeiWWVqcy3elW84k/sBKHQB0N13i3OfnrGk=; b=mPe/QjpIs3UEVPbAcscrHQ1z79nY0BFg7+8/bnjwkbqhl4OOCiWNPQAMG+ziCg33RP 3rOWna9q8fqAPai7o1r/1HKd16HiMws8jNl+RaJ5oAQQDTzF+Vd0JKjEHVzq9VzsvVvO YE5YTn7EGH3YmMW4WHq7JPgWfw441XSCCp/rdszyIZObKgQjmCxfHp8HABdVGVC6RdtO 2Ex+SYdZvTcpLgJ16NRweCA/D2zO2bU3kahhyFfEZCPUl5CUpdLV4f+1/LovZHietEC4 KsHjIthUlp6lReJRD4L+c5jI/QJyMrj4ESTxc9RgkVnRQ69Vd0mh56OUBSDHfGZiZ9hQ jFog== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of oleg@redhat.com designates 66.187.233.73 as permitted sender) smtp.mailfrom=oleg@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of oleg@redhat.com designates 66.187.233.73 as permitted sender) smtp.mailfrom=oleg@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Date: Fri, 16 Mar 2018 12:39:18 +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: <20180316113917.GA21303@redhat.com> References: <20180313125603.19819-1-ravi.bangoria@linux.vnet.ibm.com> <20180313125603.19819-6-ravi.bangoria@linux.vnet.ibm.com> <20180315142120.GA19218@redhat.com> <20180315143044.GA19643@redhat.com> <3b303a2d-35dd-9178-fc03-de9f2d588797@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3b303a2d-35dd-9178-fc03-de9f2d588797@linux.vnet.ibm.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594827101403620100?= X-GMAIL-MSGID: =?utf-8?q?1595094195351289726?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 03/16, Ravi Bangoria wrote: > > On 03/15/2018 08:00 PM, Oleg Nesterov wrote: > > Note to mention that sdt_find_vma() can return NULL but the callers do > > vma_offset_to_vaddr(vma) without any check. > > If the "mm" we are passing to sdt_find_vma() is returned by > uprobe_build_map_info(ref_ctr_offset), sdt_find_vma() must > _not_ return NULL. Not at all. Once build_map_info() returns any mapping can go away. Otherwise, why do you think the caller has to take ->mmap_sem and use find_vma()? If you were right, build_map_info() could just return the list of vma's instead of list of mm's. Oleg.