linux-kernel - Re: [PATCH v4 1/2] memremap: rename MEMORY_DEVICE_DEVDAX to MEMORY_DEVICE

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Message-ID: <20200831205655.GK1422350@iweiny-DESK2.sc.intel.com>
Date:   Mon, 31 Aug 2020 13:56:55 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     Roger Pau Monné <roger.pau@...rix.com>
Cc:     Dan Williams <dan.j.williams@...el.com>,
        David Hildenbrand <david@...hat.com>,
        linux-kernel@...r.kernel.org,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        Logan Gunthorpe <logang@...tatee.com>,
        linux-nvdimm@...ts.01.org, xen-devel@...ts.xenproject.org,
        linux-mm@...ck.org
Subject: Re: [PATCH v4 1/2] memremap: rename MEMORY_DEVICE_DEVDAX to
 MEMORY_DEVICE_GENERIC

On Mon, Aug 31, 2020 at 12:19:07PM +0200, Roger Pau Monné wrote:
> On Thu, Aug 20, 2020 at 01:37:41PM +0200, Roger Pau Monné wrote:
> > On Tue, Aug 11, 2020 at 11:07:36PM +0200, David Hildenbrand wrote:
> > > On 11.08.20 11:44, Roger Pau Monne wrote:
> > > > This is in preparation for the logic behind MEMORY_DEVICE_DEVDAX also
> > > > being used by non DAX devices.
> > > > 
> > > > No functional change intended.
> > > > 
> > > > Signed-off-by: Roger Pau Monné <roger.pau@...rix.com>

Dan is out on leave so I'll chime in.

I can't really justify keeping this as DEVDAX if there is another user who
needs the same type of mapping.

Sorry for the delay.

Reviewed-by: Ira Weiny <ira.weiny@...el.com>

> > > > ---
> > > > Cc: Dan Williams <dan.j.williams@...el.com>
> > > > Cc: Vishal Verma <vishal.l.verma@...el.com>
> > > > Cc: Dave Jiang <dave.jiang@...el.com>
> > > > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > > > Cc: Jason Gunthorpe <jgg@...pe.ca>
> > > > Cc: Ira Weiny <ira.weiny@...el.com>
> > > > Cc: "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
> > > > Cc: Johannes Thumshirn <jthumshirn@...e.de>
> > > > Cc: Logan Gunthorpe <logang@...tatee.com>
> > > > Cc: linux-nvdimm@...ts.01.org
> > > > Cc: xen-devel@...ts.xenproject.org
> > > > Cc: linux-mm@...ck.org
> > > > ---
> > > >  drivers/dax/device.c     | 2 +-
> > > >  include/linux/memremap.h | 9 ++++-----
> > > >  mm/memremap.c            | 2 +-
> > > >  3 files changed, 6 insertions(+), 7 deletions(-)
> > > > 
> > > > diff --git a/drivers/dax/device.c b/drivers/dax/device.c
> > > > index 4c0af2eb7e19..1e89513f3c59 100644
> > > > --- a/drivers/dax/device.c
> > > > +++ b/drivers/dax/device.c
> > > > @@ -429,7 +429,7 @@ int dev_dax_probe(struct device *dev)
> > > >  		return -EBUSY;
> > > >  	}
> > > >  
> > > > -	dev_dax->pgmap.type = MEMORY_DEVICE_DEVDAX;
> > > > +	dev_dax->pgmap.type = MEMORY_DEVICE_GENERIC;
> > > >  	addr = devm_memremap_pages(dev, &dev_dax->pgmap);
> > > >  	if (IS_ERR(addr))
> > > >  		return PTR_ERR(addr);
> > > > diff --git a/include/linux/memremap.h b/include/linux/memremap.h
> > > > index 5f5b2df06e61..e5862746751b 100644
> > > > --- a/include/linux/memremap.h
> > > > +++ b/include/linux/memremap.h
> > > > @@ -46,11 +46,10 @@ struct vmem_altmap {
> > > >   * wakeup is used to coordinate physical address space management (ex:
> > > >   * fs truncate/hole punch) vs pinned pages (ex: device dma).
> > > >   *
> > > > - * MEMORY_DEVICE_DEVDAX:
> > > > + * MEMORY_DEVICE_GENERIC:
> > > >   * Host memory that has similar access semantics as System RAM i.e. DMA
> > > > - * coherent and supports page pinning. In contrast to
> > > > - * MEMORY_DEVICE_FS_DAX, this memory is access via a device-dax
> > > > - * character device.
> > > > + * coherent and supports page pinning. This is for example used by DAX devices
> > > > + * that expose memory using a character device.
> > > >   *
> > > >   * MEMORY_DEVICE_PCI_P2PDMA:
> > > >   * Device memory residing in a PCI BAR intended for use with Peer-to-Peer
> > > > @@ -60,7 +59,7 @@ enum memory_type {
> > > >  	/* 0 is reserved to catch uninitialized type fields */
> > > >  	MEMORY_DEVICE_PRIVATE = 1,
> > > >  	MEMORY_DEVICE_FS_DAX,
> > > > -	MEMORY_DEVICE_DEVDAX,
> > > > +	MEMORY_DEVICE_GENERIC,
> > > >  	MEMORY_DEVICE_PCI_P2PDMA,
> > > >  };
> > > >  
> > > > diff --git a/mm/memremap.c b/mm/memremap.c
> > > > index 03e38b7a38f1..006dace60b1a 100644
> > > > --- a/mm/memremap.c
> > > > +++ b/mm/memremap.c
> > > > @@ -216,7 +216,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> > > >  			return ERR_PTR(-EINVAL);
> > > >  		}
> > > >  		break;
> > > > -	case MEMORY_DEVICE_DEVDAX:
> > > > +	case MEMORY_DEVICE_GENERIC:
> > > >  		need_devmap_managed = false;
> > > >  		break;
> > > >  	case MEMORY_DEVICE_PCI_P2PDMA:
> > > > 
> > > 
> > > No strong opinion (@Dan?), I do wonder if a separate type would make sense.
> > 
> > Gentle ping.
> 
> Sorry to ping again, but I would rather get this out of my queue if
> possible, seeing as the other patch is OK to go in but depends on this
> one going in first.
> 
> Thanks, Roger.