From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 55306210EB4DD for ; Fri, 10 Aug 2018 09:18:12 -0700 (PDT) Subject: Re: Help trying to use /dev/pmem for dax debugging? References: <20180730235312.GA5089@thunk.org> <20180731193642.GA3473@linux.intel.com> <30247efc-88f8-3e0b-fcd8-83801be5f041@intel.com> <20180810025339.GB21087@thunk.org> From: Dave Jiang Message-ID: <4222843a-13ea-e88f-ca74-4e3fe53b4105@intel.com> Date: Fri, 10 Aug 2018 09:18:11 -0700 MIME-Version: 1.0 In-Reply-To: <20180810025339.GB21087@thunk.org> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: "Theodore Y. Ts'o" Cc: linux-ext4@vger.kernel.org, Matthew Wilcox , linux-nvdimm@lists.01.org List-ID: On 08/09/2018 07:53 PM, Theodore Y. Ts'o wrote: > On Tue, Jul 31, 2018 at 01:27:15PM -0700, Dave Jiang wrote: >> >> On 7/31/2018 12:36 PM, Ross Zwisler wrote: >>> On Mon, Jul 30, 2018 at 07:53:12PM -0400, Theodore Y. Ts'o wrote: >>>> In newer kernels, it looks like you can't use /dev/pmem0 for DAX >>>> unless it's marked as being DAX capable. This appears to require >>>> CONFIG_NVDIMM_PFN. But when I tried to build a kernel with that >>>> configured, I get the following BUG: >>> >>> You're using the memmap kernel command line parameter to reserve normal >>> memory to be treated as normal memory, but you've also got kernel address >>> randomization turned on in your kernel config: >>> >>> CONFIG_RANDOMIZE_BASE=y >>> CONFIG_RANDOMIZE_MEMORY=y >>> >>> You need to turn these off for the memmap kernel command line parameter, else >>> the memory we're using could overlap with addresses used for other things. >> >> I believe this issue was fixed a while back. Although we probably can see if >> that is the issue or something else. > > I turned off RANDOMIZE_BASE and RANDOMIZE_MEMORY, but that didn't fix > my problem. > > It turns out the problem was KASAN. It looks like using memmap to > create test /dev/pmemX devices is not compatible with CONFIG_KASAN > being enabled. > > So I have a workaround for now, but it seems this to be a bug in > KASAN, or at least an unfortunate interaction between KASAN and > NVDIMM_PFN. Thanks Ted. I have updated the wiki Ross mentioned to reflect that. _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm