From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) (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 60834210C123B for ; Tue, 31 Jul 2018 13:27:17 -0700 (PDT) Subject: Re: Help trying to use /dev/pmem for dax debugging? References: <20180730235312.GA5089@thunk.org> <20180731193642.GA3473@linux.intel.com> From: Dave Jiang Message-ID: <30247efc-88f8-3e0b-fcd8-83801be5f041@intel.com> Date: Tue, 31 Jul 2018 13:27:15 -0700 MIME-Version: 1.0 In-Reply-To: <20180731193642.GA3473@linux.intel.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Ross Zwisler , "Theodore Y. Ts'o" Cc: linux-ext4@vger.kernel.org, Matthew Wilcox , linux-nvdimm@lists.01.org List-ID: 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: >> >> [ 0.000000] Linux version 4.18.0-rc4-xfstests-00031-g7c2d77aa7d80 (tytso@cwcc) (gcc version 7.3.0 (Debian 7.3.0-27)) #460 SMP Mon Jul 30 19:38:44 EDT 2018 >> [ 0.000000] Command line: systemd.show_status=auto systemd.log_level=crit root=/dev/vda console=ttyS0,115200 cmd=maint fstesttz=America/New_York fstesttyp=ext4 fstestapi=1.4 memmap=4G!9G memmap=9G!14G > Hey Ted, > > 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. > > Once that is off you probably want to double check that the addresses you're > reserving are marked as 'usable' in the e820 table. Gory details here, sorry > for the huge link: > > https://nvdimm.wiki.kernel.org/how_to_choose_the_correct_memmap_kernel_parameter_for_pmem_on_your_system > > - Ross > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@lists.01.org > https://lists.01.org/mailman/listinfo/linux-nvdimm _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm