Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20190124231441.37A4A305@viggo.jf.intel.com> <20190124231448.E102D18E@viggo.jf.intel.com>
 <c4c6aca8-6ee8-be10-65ae-4cbe0aa03bfb@inria.fr> <26ac36f4-7391-5321-217b-50d67e2119d7@intel.com>
 <453f13cd-a7fe-33eb-9a27-8490825ca29c@inria.fr> <CAPcyv4jF7ZyKaFDw7nb04UvWkVWGJdLGkZDQ1g=X7i+kdu7JRg@mail.gmail.com>
 <a3bfe739-228e-26fe-90f7-4a4f8ceb3a9a@inria.fr>
In-Reply-To: <a3bfe739-228e-26fe-90f7-4a4f8ceb3a9a@inria.fr>
From:   Dan Williams <dan.j.williams@intel.com>
Date:   Wed, 13 Feb 2019 00:24:04 -0800
Message-ID: <CAPcyv4jJ=C7ZEsJqBxzBMsQWz4+C8BZmWuk7OkztOebprd2rMg@mail.gmail.com>
Subject: Re: [PATCH 5/5] dax: "Hotplug" persistent memory for use like normal RAM
To:     Brice Goglin <Brice.Goglin@inria.fr>
Cc:     Dave Hansen <dave.hansen@intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Michal Hocko <mhocko@suse.com>,
        linux-nvdimm <linux-nvdimm@lists.01.org>,
        Takashi Iwai <tiwai@suse.de>,
        Ross Zwisler <zwisler@kernel.org>,
        Linux MM <linux-mm@kvack.org>,
        =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        Fengguang Wu <fengguang.wu@intel.com>,
        Yaowei Bai <baiyaowei@cmss.chinamobile.com>,
        "Huang, Ying" <ying.huang@intel.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Borislav Petkov <bp@suse.de>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Feb 13, 2019 at 12:12 AM Brice Goglin <Brice.Goglin@inria.fr> wrote=
:
>
> Le 13/02/2019 =C3=A0 01:30, Dan Williams a =C3=A9crit :
> > On Tue, Feb 12, 2019 at 11:59 AM Brice Goglin <Brice.Goglin@inria.fr> w=
rote:
> >> # ndctl disable-region all
> >> # ndctl zero-labels all
> >> # ndctl enable-region region0
> >> # ndctl create-namespace -r region0 -t pmem -m devdax
> >> {
> >>   "dev":"namespace0.0",
> >>   "mode":"devdax",
> >>   "map":"dev",
> >>   "size":"1488.37 GiB (1598.13 GB)",
> >>   "uuid":"ad0096d7-3fe7-4402-b529-ad64ed0bf789",
> >>   "daxregion":{
> >>     "id":0,
> >>     "size":"1488.37 GiB (1598.13 GB)",
> >>     "align":2097152,
> >>     "devices":[
> >>       {
> >>         "chardev":"dax0.0",
> >>         "size":"1488.37 GiB (1598.13 GB)"
> >>       }
> >>     ]
> >>   },
> >>   "align":2097152
> >> }
> >> # ndctl enable-namespace namespace0.0
> >> # echo -n dax0.0 > /sys/bus/dax/drivers/device_dax/remove_id
> >> <hang>
> >>
> >> I tried with and without dax_pmem_compat loaded, but it doesn't help.
> > I think this is due to:
> >
> >   a9f1ffdb6a20 device-dax: Auto-bind device after successful new_id
> >
> > I missed that this path is also called in the remove_id path. Thanks
> > for the bug report! I'll get this fixed up.
>
>
> Now that remove_id is fixed, things fails later in Dave's procedure:
>
> # echo -n dax0.0 > /sys/bus/dax/drivers/device_dax/remove_id
> # echo -n dax0.0 > /sys/bus/dax/drivers/device_dax/unbind
> # echo -n dax0.0 > /sys/bus/dax/drivers/kmem/new_id

In the current version of the code the bind is not necessary, so the
lack of error messages here means the bind succeeded.

> # echo -n dax0.0 > /sys/bus/dax/drivers/kmem/bind
> -bash: echo: write error: No such device

This also happens when the device is already bound.

>
> (And nothing seems to have changed in /sys/devices/system/memory/*/state)

What does "cat /proc/iomem" say?