From owner-freebsd-dtrace@freebsd.org Wed May 11 18:51:02 2016 Return-Path: Delivered-To: freebsd-dtrace@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8F4A3B37483 for ; Wed, 11 May 2016 18:51:02 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: from mail-pa0-x234.google.com (mail-pa0-x234.google.com [IPv6:2607:f8b0:400e:c03::234]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 5FB271EB7 for ; Wed, 11 May 2016 18:51:02 +0000 (UTC) (envelope-from markjdb@gmail.com) Received: by mail-pa0-x234.google.com with SMTP id r5so21187561pag.1 for ; Wed, 11 May 2016 11:51:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=0NJJwXqS6qpcjL+uyA7ue86d1nj/oe2EUJBdvrn0468=; b=oASkSn2W4oyPRokUa4E+q62EaAP1AIlCxyloQTTMFPya2REG+Bk1QAslgGnkBtv0pB ZzDEff+Xq5O9yQT0j7df92dy6IIb31yTCRFEfcsqon3kJTyJGQhSiuGx/WtX0bkOQgfH F3v5Ly//nd7oGbPsfp4xAWsR1FoKYczpS0OY5K5+W85+7W3exo4IsN8uBrEfaZFN3a9K bypatfI7ywrpd6X14Twvd+dQ5SwkzeuEOrMSl2B7X4cIzV7eTInk94S7snSpnSdogJoE XAJnoj+U2mlbaqsLmqMtGVOFGYbFxj9W1IqSLxYei5H/pw7JAIPRWd4pa9s0+cNnlWVQ BvvQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=0NJJwXqS6qpcjL+uyA7ue86d1nj/oe2EUJBdvrn0468=; b=KmpFrnLojxHl2LmGcTwJM732b0GcjcSIcIgpY3kUa2Cw8WUD28rJu9l0lSzTmw+Azn tDHNkQjS0ViOb8Lyu9SD+o/XCs4pp9GryQwi8kFhEwz/QW/jEywou+Obz2OP9fphMbsB Gf5XiipOx5DuYEph8yN1PpfxaWvRlLnKRmWi/mDjWqshYL/75Gi8tj9AzEfQH2mdhF2j S+L4VNh0M92wKV//GpuryOqCfE5pNrRYyCt9ukTClPM1jIheKC+J+VozaRrQ9ppl+nB6 +c/6ZjQNUCs0xe+UaKOO76xDvMD4ISIv1N+HPW9mPGPR0s2Hwgm7F48wRAg0OqIGutg3 nl7A== X-Gm-Message-State: AOPr4FWfUm7CGe8qOUCzKw5Xv6Mj0tG0eL07VP17KKDG3yXqN8tL5FSh7wlXjAv3hKfwgg== X-Received: by 10.67.1.233 with SMTP id bj9mr7314023pad.46.1462992661997; Wed, 11 May 2016 11:51:01 -0700 (PDT) Received: from wkstn-mjohnston.west.isilon.com (c-76-104-201-218.hsd1.wa.comcast.net. [76.104.201.218]) by smtp.gmail.com with ESMTPSA id bf4sm13997988pac.4.2016.05.11.11.50.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 May 2016 11:51:01 -0700 (PDT) Sender: Mark Johnston Date: Wed, 11 May 2016 11:54:46 -0700 From: Mark Johnston To: Abhishek Kulkarni Cc: "freebsd-dtrace@freebsd.org" Subject: Re: Regarding Dtrace on Arm Message-ID: <20160511185446.GF76917@wkstn-mjohnston.west.isilon.com> References: <85861491-5F47-4448-B933-E1394C578646@juniper.net> <20160511164945.GB76917@wkstn-mjohnston.west.isilon.com> <812C8B41-5996-41E3-9340-3EFC0C2AD5F5@juniper.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <812C8B41-5996-41E3-9340-3EFC0C2AD5F5@juniper.net> User-Agent: Mutt/1.6.1 (2016-04-27) X-BeenThere: freebsd-dtrace@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: "A discussion list for developers working on DTrace in FreeBSD." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 11 May 2016 18:51:02 -0000 On Wed, May 11, 2016 at 06:17:51PM +0000, Abhishek Kulkarni wrote: > Thanks very much Mark. Should I raise a bug about this on freebsd.org? That would be helpful, thanks. > > Regards > Abhishek Kulkarni > > > > > On 5/11/16, 9:49 AM, "Mark Johnston" wrote: > > >On Sat, May 07, 2016 at 08:55:56PM +0000, Abhishek Kulkarni wrote: > >> Hello All, > >> > >> I was using Dtrace using the FBT provider on an arm platform with witness enabled. When FBT is used with the kernel module, it generates a kernel panic or the system becomes unresponsive. Is this problem know or seen before. I am copying the kernel backtrace below for reference. The issue seems to be with a blockable sleep lock(kld_sx) acquired which is conflicting with the td->td_critnest positive value. > > > >Unfortunately, I think this is expected. The ARM port of DTrace will > >call into the kernel linker from probe context to perform stack > >unwinding. This is a bug since the kernel linker cannot be entered in > >arbitrary contexts - the thread might already hold the linker lock, or > >might hold a critical section as in your example. > > > >This is a known issue, but I'm not sure if anyone is working on fixing > >it. > > > >-Mark