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From: Ira Weiny <ira.weiny@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "Dan Williams" <dan.j.williams@intel.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Jason Gunthorpe" <jgg@mellanox.com>,
	"Ben Skeggs" <bskeggs@redhat.com>,
	linux-nvdimm@lists.01.org, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-mm@kvack.org, nouveau@lists.freedesktop.org
Subject: Re: [PATCH 13/22] device-dax: use the dev_pagemap internal refcount
Date: Thu, 13 Jun 2019 17:22:17 -0700
Message-ID: <20190614002217.GB783@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20190613094326.24093-14-hch@lst.de>

On Thu, Jun 13, 2019 at 11:43:16AM +0200, Christoph Hellwig wrote:
> The functionality is identical to the one currently open coded in
> device-dax.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/dax/dax-private.h |  4 ---
>  drivers/dax/device.c      | 52 +--------------------------------------
>  2 files changed, 1 insertion(+), 55 deletions(-)
> 
> diff --git a/drivers/dax/dax-private.h b/drivers/dax/dax-private.h
> index a45612148ca0..ed04a18a35be 100644
> --- a/drivers/dax/dax-private.h
> +++ b/drivers/dax/dax-private.h
> @@ -51,8 +51,6 @@ 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)
> - * @ref: pgmap reference count (driver owned)
> - * @cmp: @ref final put completion (driver owned)
>   */
>  struct dev_dax {
>  	struct dax_region *region;
> @@ -60,8 +58,6 @@ struct dev_dax {
>  	int target_node;
>  	struct device dev;
>  	struct dev_pagemap pgmap;
> -	struct percpu_ref ref;
> -	struct completion cmp;
>  };
>  
>  static inline struct dev_dax *to_dev_dax(struct device *dev)
> diff --git a/drivers/dax/device.c b/drivers/dax/device.c
> index e23fa1bd8c97..a9d7c90ecf1e 100644
> --- a/drivers/dax/device.c
> +++ b/drivers/dax/device.c
> @@ -14,37 +14,6 @@
>  #include "dax-private.h"
>  #include "bus.h"
>  
> -static struct dev_dax *ref_to_dev_dax(struct percpu_ref *ref)
> -{
> -	return container_of(ref, struct dev_dax, ref);
> -}
> -
> -static void dev_dax_percpu_release(struct percpu_ref *ref)
> -{
> -	struct dev_dax *dev_dax = ref_to_dev_dax(ref);
> -
> -	dev_dbg(&dev_dax->dev, "%s\n", __func__);
> -	complete(&dev_dax->cmp);
> -}
> -
> -static void dev_dax_percpu_exit(void *data)
> -{
> -	struct percpu_ref *ref = data;
> -	struct dev_dax *dev_dax = ref_to_dev_dax(ref);
> -
> -	dev_dbg(&dev_dax->dev, "%s\n", __func__);
> -	wait_for_completion(&dev_dax->cmp);
> -	percpu_ref_exit(ref);
> -}
> -
> -static void dev_dax_percpu_kill(struct dev_pagemap *pgmap)
> -{
> -	struct dev_dax *dev_dax = container_of(pgmap, struct dev_dax, pgmap);
> -
> -	dev_dbg(&dev_dax->dev, "%s\n", __func__);
> -	percpu_ref_kill(pgmap->ref);
> -}
> -
>  static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
>  		const char *func)
>  {
> @@ -442,10 +411,6 @@ static void dev_dax_kill(void *dev_dax)
>  	kill_dev_dax(dev_dax);
>  }
>  
> -static const struct dev_pagemap_ops dev_dax_pagemap_ops = {
> -	.kill		= dev_dax_percpu_kill,
> -};
> -
>  int dev_dax_probe(struct device *dev)
>  {
>  	struct dev_dax *dev_dax = to_dev_dax(dev);
> @@ -463,24 +428,9 @@ int dev_dax_probe(struct device *dev)
>  		return -EBUSY;
>  	}
>  
> -	init_completion(&dev_dax->cmp);
> -	rc = percpu_ref_init(&dev_dax->ref, dev_dax_percpu_release, 0,
> -			GFP_KERNEL);
> -	if (rc)
> -		return rc;
> -
> -	rc = devm_add_action_or_reset(dev, dev_dax_percpu_exit, &dev_dax->ref);
> -	if (rc)
> -		return rc;
> -
> -	dev_dax->pgmap.ref = &dev_dax->ref;

I don't think this exactly correct.  pgmap.ref is a pointer to the dev_dax ref
structure.  Taking it away will cause devm_memremap_pages() to fail AFAICS.

I think you need to change struct dev_pagemap as well:

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index f0628660d541..5e2120589ddf 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -90,7 +90,7 @@ struct dev_pagemap {
        struct vmem_altmap altmap;
        bool altmap_valid;
        struct resource res;
-       struct percpu_ref *ref;
+       struct percpu_ref ref;
        void (*kill)(struct percpu_ref *ref);
        struct device *dev;
        void *data;

And all usages of it, right?

Ira

> -	dev_dax->pgmap.ops = &dev_dax_pagemap_ops;
>  	addr = devm_memremap_pages(dev, &dev_dax->pgmap);
> -	if (IS_ERR(addr)) {
> -		devm_remove_action(dev, dev_dax_percpu_exit, &dev_dax->ref);
> -		percpu_ref_exit(&dev_dax->ref);
> +	if (IS_ERR(addr))
>  		return PTR_ERR(addr);
> -	}
>  
>  	inode = dax_inode(dax_dev);
>  	cdev = inode->i_cdev;
> -- 
> 2.20.1
> 
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@lists.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm

  reply index

Thread overview: 103+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-13  9:43 dev_pagemap related cleanups Christoph Hellwig
2019-06-13  9:43 ` [PATCH 01/22] mm: remove the unused ARCH_HAS_HMM_DEVICE Kconfig option Christoph Hellwig
2019-06-13 18:30   ` Jason Gunthorpe
2019-06-13  9:43 ` [PATCH 02/22] mm: remove the struct hmm_device infrastructure Christoph Hellwig
2019-06-13 18:46   ` Jason Gunthorpe
2019-06-13 23:06   ` [Nouveau] " John Hubbard
2019-06-13  9:43 ` [PATCH 03/22] mm: remove hmm_devmem_add_resource Christoph Hellwig
2019-06-13 18:52   ` Jason Gunthorpe
2019-06-14  6:19     ` Christoph Hellwig
2019-06-14  0:54   ` [Nouveau] " John Hubbard
2019-06-20 19:32   ` Michal Hocko
2019-06-13  9:43 ` [PATCH 04/22] mm: don't clear ->mapping in hmm_devmem_free Christoph Hellwig
2019-06-13 19:05   ` Jason Gunthorpe
2019-06-14  6:21     ` Christoph Hellwig
2019-06-14  1:46   ` John Hubbard
2019-06-20 19:36   ` Michal Hocko
2019-06-13  9:43 ` [PATCH 05/22] mm: export alloc_pages_vma Christoph Hellwig
2019-06-14  1:47   ` John Hubbard
2019-06-14  6:23     ` Christoph Hellwig
2019-06-20 19:17   ` Michal Hocko
2019-06-24 18:24     ` Dan Williams
2019-06-25  7:23       ` Christoph Hellwig
2019-06-25 15:00         ` Michal Hocko
2019-06-25 18:03           ` Dan Williams
2019-06-25 19:00             ` Michal Hocko
2019-06-25 19:52               ` Dan Williams
2019-06-26  5:46                 ` Michal Hocko
2019-06-26 16:14                   ` Dan Williams
2019-06-27  6:41                     ` Michal Hocko
2019-06-13  9:43 ` [PATCH 06/22] mm: factor out a devm_request_free_mem_region helper Christoph Hellwig
2019-06-13 19:16   ` Jason Gunthorpe
2019-06-14  6:24     ` Christoph Hellwig
2019-06-15  2:21   ` John Hubbard
2019-06-15 14:30     ` Christoph Hellwig
2019-06-13  9:43 ` [PATCH 07/22] memremap: move dev_pagemap callbacks into a separate structure Christoph Hellwig
2019-06-13 19:18   ` Jason Gunthorpe
2019-06-13 20:14   ` Logan Gunthorpe
2019-06-13  9:43 ` [PATCH 08/22] memremap: pass a struct dev_pagemap to ->kill Christoph Hellwig
2019-06-13 19:26   ` Jason Gunthorpe
2019-06-13 20:12   ` Logan Gunthorpe
2019-06-13 20:15     ` Dan Williams
2019-06-13  9:43 ` [PATCH 09/22] memremap: lift the devmap_enable manipulation into devm_memremap_pages Christoph Hellwig
2019-06-13 19:34   ` Jason Gunthorpe
2019-06-13 20:13     ` Dan Williams
2019-06-14  6:28     ` Christoph Hellwig
2019-06-13  9:43 ` [PATCH 10/22] memremap: add a migrate callback to struct dev_pagemap_ops Christoph Hellwig
2019-06-13 23:42   ` Ralph Campbell
2019-06-14  6:33     ` Christoph Hellwig
2019-06-13  9:43 ` [PATCH 11/22] memremap: remove the data field in struct dev_pagemap Christoph Hellwig
2019-06-13 19:37   ` Jason Gunthorpe
2019-06-13  9:43 ` [PATCH 12/22] memremap: provide an optional internal refcount " Christoph Hellwig
2019-06-13  9:43 ` [PATCH 13/22] device-dax: use the dev_pagemap internal refcount Christoph Hellwig
2019-06-14  0:22   ` Ira Weiny [this message]
2019-06-14  6:35     ` Christoph Hellwig
2019-06-13  9:43 ` [PATCH 14/22] nouveau: use alloc_page_vma directly Christoph Hellwig
2019-06-13 19:39   ` Jason Gunthorpe
2019-06-13  9:43 ` [PATCH 15/22] nouveau: use devm_memremap_pages directly Christoph Hellwig
2019-06-13  9:43 ` [PATCH 16/22] mm: remove hmm_vma_alloc_locked_page Christoph Hellwig
2019-06-13  9:43 ` [PATCH 17/22] mm: remove hmm_devmem_add Christoph Hellwig
2019-06-13 19:42   ` Jason Gunthorpe
2019-06-14  6:39     ` Christoph Hellwig
2019-06-13  9:43 ` [PATCH 18/22] mm: mark DEVICE_PUBLIC as broken Christoph Hellwig
2019-06-13 19:44   ` Jason Gunthorpe
2019-06-13 19:53     ` Ralph Campbell
2019-06-13 19:58       ` Jason Gunthorpe
2019-06-14  0:43         ` Ira Weiny
2019-06-14  1:23           ` John Hubbard
2019-06-19 19:27             ` Jason Gunthorpe
2019-06-19 19:46               ` Dan Williams
2019-06-26  3:15               ` John Hubbard
2019-06-26  5:45                 ` Michal Hocko
2019-06-26  6:07                   ` John Hubbard
2019-06-14  6:43           ` Christoph Hellwig
2019-06-20 19:26   ` Michal Hocko
2019-06-25  7:29     ` Christoph Hellwig
2019-06-25 11:44       ` Jason Gunthorpe
2019-06-25 11:59         ` Christoph Hellwig
2019-06-13  9:43 ` [PATCH 19/22] mm: simplify ZONE_DEVICE page private data Christoph Hellwig
2019-06-13  9:43 ` [PATCH 20/22] mm: sort out the DEVICE_PRIVATE Kconfig mess Christoph Hellwig
2019-06-13 19:55   ` Jason Gunthorpe
2019-06-13  9:43 ` [PATCH 21/22] mm: remove the HMM config option Christoph Hellwig
2019-06-13 20:01   ` Jason Gunthorpe
2019-06-14  6:47     ` Christoph Hellwig
2019-06-13  9:43 ` [PATCH 22/22] mm: don't select MIGRATE_VMA_HELPER from HMM_MIRROR Christoph Hellwig
2019-06-13 20:04   ` Jason Gunthorpe
2019-06-14  1:53   ` [Nouveau] " John Hubbard
2019-06-14  6:48     ` Christoph Hellwig
2019-06-13 14:16 ` dev_pagemap related cleanups Jason Gunthorpe
2019-06-14  6:12   ` Christoph Hellwig
2019-06-13 18:27 ` Dan Williams
2019-06-13 20:17   ` Logan Gunthorpe
2019-06-13 20:21     ` Dan Williams
2019-06-13 20:24       ` Logan Gunthorpe
2019-06-13 20:48         ` Andrew Morton
2019-06-13 20:40   ` Jason Gunthorpe
2019-06-13 21:21     ` Christoph Hellwig
2019-06-13 23:10       ` Jason Gunthorpe
2019-06-14  6:14         ` Christoph Hellwig
2019-06-14  0:31     ` Ira Weiny
2019-06-14  6:13   ` Christoph Hellwig
2019-06-15  1:14     ` Dan Williams
2019-06-15  8:33       ` Christoph Hellwig
2019-06-15 18:09         ` Dan Williams

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