Re: [PATCH v5 01/17] device-dax: make pgmap optional for instance creation

From: David Hildenbrand <david@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	Brice Goglin <Brice.Goglin@inria.fr>, Jia He <justin.he@arm.com>,
	Joao Martins <joao.m.martins@oracle.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	Linux MM <linux-mm@kvack.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 01/17] device-dax: make pgmap optional for instance creation
Date: Thu, 1 Oct 2020 19:39:03 +0200	[thread overview]
Message-ID: <8012a7c2-750f-38e1-0df0-200b56109fd6@redhat.com> (raw)
In-Reply-To: <CAPcyv4io6a7qaX+oa8uL9C0nc9J9UMx0CfC5E1DYdhSPvYVeOw@mail.gmail.com>

On 01.10.20 18:54, Dan Williams wrote:
> On Thu, Oct 1, 2020 at 1:41 AM David Hildenbrand <david@redhat.com> wrote:
>>
>> On 25.09.20 21:11, Dan Williams wrote:
>>> The passed in dev_pagemap is only required in the pmem case as the
>>> libnvdimm core may have reserved a vmem_altmap for dev_memremap_pages() to
>>> place the memmap in pmem directly.  In the hmem case there is no agent
>>> reserving an altmap so it can all be handled by a core internal default.
>>>
>>> Pass the resource range via a new @range property of 'struct
>>> dev_dax_data'.
>>>
>>> Link: https://lkml.kernel.org/r/159643099958.4062302.10379230791041872886.stgit@dwillia2-desk3.amr.corp.intel.com
>>> Cc: David Hildenbrand <david@redhat.com>
>>> Cc: Vishal Verma <vishal.l.verma@intel.com>
>>> Cc: Dave Hansen <dave.hansen@linux.intel.com>
>>> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
>>> Cc: Brice Goglin <Brice.Goglin@inria.fr>
>>> Cc: Dave Jiang <dave.jiang@intel.com>
>>> Cc: David Hildenbrand <david@redhat.com>
>>> Cc: Ira Weiny <ira.weiny@intel.com>
>>> Cc: Jia He <justin.he@arm.com>
>>> Cc: Joao Martins <joao.m.martins@oracle.com>
>>> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>>> ---
>>>  drivers/dax/bus.c              |   29 +++++++++++++++--------------
>>>  drivers/dax/bus.h              |    2 ++
>>>  drivers/dax/dax-private.h      |    9 ++++++++-
>>>  drivers/dax/device.c           |   28 +++++++++++++++++++---------
>>>  drivers/dax/hmem/hmem.c        |    8 ++++----
>>>  drivers/dax/kmem.c             |   12 ++++++------
>>>  drivers/dax/pmem/core.c        |    4 ++++
>>>  tools/testing/nvdimm/dax-dev.c |    8 ++++----
>>>  8 files changed, 62 insertions(+), 38 deletions(-)
>>>
>>> diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
>>> index dffa4655e128..96bd64ba95a5 100644
>>> --- a/drivers/dax/bus.c
>>> +++ b/drivers/dax/bus.c
>>> @@ -271,7 +271,7 @@ static ssize_t size_show(struct device *dev,
>>>               struct device_attribute *attr, char *buf)
>>>  {
>>>       struct dev_dax *dev_dax = to_dev_dax(dev);
>>> -     unsigned long long size = resource_size(&dev_dax->region->res);
>>> +     unsigned long long size = range_len(&dev_dax->range);
>>>
>>>       return sprintf(buf, "%llu\n", size);
>>>  }
>>> @@ -293,19 +293,12 @@ static ssize_t target_node_show(struct device *dev,
>>>  }
>>>  static DEVICE_ATTR_RO(target_node);
>>>
>>> -static unsigned long long dev_dax_resource(struct dev_dax *dev_dax)
>>> -{
>>> -     struct dax_region *dax_region = dev_dax->region;
>>> -
>>> -     return dax_region->res.start;
>>> -}
>>> -
>>>  static ssize_t resource_show(struct device *dev,
>>>               struct device_attribute *attr, char *buf)
>>>  {
>>>       struct dev_dax *dev_dax = to_dev_dax(dev);
>>>
>>> -     return sprintf(buf, "%#llx\n", dev_dax_resource(dev_dax));
>>> +     return sprintf(buf, "%#llx\n", dev_dax->range.start);
>>>  }
>>>  static DEVICE_ATTR(resource, 0400, resource_show, NULL);
>>>
>>> @@ -376,6 +369,7 @@ static void dev_dax_release(struct device *dev)
>>>
>>>       dax_region_put(dax_region);
>>>       put_dax(dax_dev);
>>> +     kfree(dev_dax->pgmap);
>>>       kfree(dev_dax);
>>>  }
>>>
>>> @@ -412,7 +406,12 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
>>>       if (!dev_dax)
>>>               return ERR_PTR(-ENOMEM);
>>>
>>> -     memcpy(&dev_dax->pgmap, data->pgmap, sizeof(struct dev_pagemap));
>>> +     if (data->pgmap) {
>>> +             dev_dax->pgmap = kmemdup(data->pgmap,
>>> +                             sizeof(struct dev_pagemap), GFP_KERNEL);
>>> +             if (!dev_dax->pgmap)
>>> +                     goto err_pgmap;
>>> +     }
>>>
>>>       /*
>>>        * No 'host' or dax_operations since there is no access to this
>>> @@ -421,18 +420,19 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
>>>       dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
>>>       if (IS_ERR(dax_dev)) {
>>>               rc = PTR_ERR(dax_dev);
>>> -             goto err;
>>> +             goto err_alloc_dax;
>>>       }
>>>
>>>       /* a device_dax instance is dead while the driver is not attached */
>>>       kill_dax(dax_dev);
>>>
>>> -     /* from here on we're committed to teardown via dax_dev_release() */
>>> +     /* from here on we're committed to teardown via dev_dax_release() */
>>>       dev = &dev_dax->dev;
>>>       device_initialize(dev);
>>>
>>>       dev_dax->dax_dev = dax_dev;
>>>       dev_dax->region = dax_region;
>>> +     dev_dax->range = data->range;
>>>       dev_dax->target_node = dax_region->target_node;
>>>       kref_get(&dax_region->kref);
>>>
>>> @@ -458,8 +458,9 @@ struct dev_dax *devm_create_dev_dax(struct dev_dax_data *data)
>>>               return ERR_PTR(rc);
>>>
>>>       return dev_dax;
>>> -
>>> - err:
>>> +err_alloc_dax:
>>> +     kfree(dev_dax->pgmap);
>>> +err_pgmap:
>>>       kfree(dev_dax);
>>>
>>>       return ERR_PTR(rc);
>>> diff --git a/drivers/dax/bus.h b/drivers/dax/bus.h
>>> index 299c2e7fac09..4aeb36da83a4 100644
>>> --- a/drivers/dax/bus.h
>>> +++ b/drivers/dax/bus.h
>>> @@ -3,6 +3,7 @@
>>>  #ifndef __DAX_BUS_H__
>>>  #define __DAX_BUS_H__
>>>  #include <linux/device.h>
>>> +#include <linux/range.h>
>>>
>>>  struct dev_dax;
>>>  struct resource;
>>> @@ -21,6 +22,7 @@ struct dev_dax_data {
>>>       struct dax_region *dax_region;
>>>       struct dev_pagemap *pgmap;
>>>       enum dev_dax_subsys subsys;
>>> +     struct range range;
>>>       int id;
>>>  };
>>>
>>> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
>>> index 8a4c40ccd2ef..6779f683671d 100644
>>> --- a/drivers/dax/dax-private.h
>>> +++ b/drivers/dax/dax-private.h
>>> @@ -41,6 +41,7 @@ struct dax_region {
>>>   * @target_node: effective numa node if dev_dax memory range is onlined
>>>   * @dev - device core
>>>   * @pgmap - pgmap for memmap setup / lifetime (driver owned)
>>> + * @range: resource range for the instance
>>>   * @dax_mem_res: physical address range of hotadded DAX memory
>>>   * @dax_mem_name: name for hotadded DAX memory via add_memory_driver_managed()
>>>   */
>>> @@ -49,10 +50,16 @@ struct dev_dax {
>>>       struct dax_device *dax_dev;
>>>       int target_node;
>>>       struct device dev;
>>> -     struct dev_pagemap pgmap;
>>> +     struct dev_pagemap *pgmap;
>>> +     struct range range;
>>>       struct resource *dax_kmem_res;
>>>  };
>>>
>>> +static inline u64 range_len(struct range *range)
>>> +{
>>> +     return range->end - range->start + 1;
>>> +}
>>
>> include/linux/range.h seems to have this function - why is this here needed?
> 
> It's there because I add it later in this series. I waited until
> "mm/memremap_pages: convert to 'struct range'" to make it global as
> that's the first kernel-wide visible usage of it.

Ah okay - I'd just place it right at the final destination, instead of
moving fresh code around within a single series.

-- 
Thanks,

David / dhildenb
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