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Subject: Re: [PATCH v5 10/17] mm/memremap_pages: convert to 'struct range'
To:     Dan Williams <dan.j.williams@intel.com>, akpm@linux-foundation.org
Cc:     Paul Mackerras <paulus@ozlabs.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Vivek Goyal <vgoyal@redhat.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Ben Skeggs <bskeggs@redhat.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Ira Weiny <ira.weiny@intel.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Juergen Gross <jgross@suse.com>,
        Stefano Stabellini <sstabellini@kernel.org>,
        =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
        dave.hansen@linux.intel.com, linux-mm@kvack.org,
        linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org
References: <160106109960.30709.7379926726669669398.stgit@dwillia2-desk3.amr.corp.intel.com>
 <160106115761.30709.13539840236873663620.stgit@dwillia2-desk3.amr.corp.intel.com>
From:   boris.ostrovsky@oracle.com
Organization: Oracle Corporation
Message-ID: <6186fa28-d123-12db-6171-a75cb6e615a5@oracle.com>
Date:   Mon, 28 Sep 2020 15:12:32 -0400
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On 9/25/20 3:12 PM, Dan Williams wrote:
>  
> diff --git a/drivers/xen/unpopulated-alloc.c b/drivers/xen/unpopulated-alloc.c
> index 3b98dc921426..091b8669eca3 100644
> --- a/drivers/xen/unpopulated-alloc.c
> +++ b/drivers/xen/unpopulated-alloc.c
> @@ -18,27 +18,37 @@ static unsigned int list_count;
>  static int fill_list(unsigned int nr_pages)
>  {
>  	struct dev_pagemap *pgmap;
> +	struct resource *res;
>  	void *vaddr;
>  	unsigned int i, alloc_pages = round_up(nr_pages, PAGES_PER_SECTION);
> -	int ret;
> +	int ret = -ENOMEM;
> +
> +	res = kzalloc(sizeof(*res), GFP_KERNEL);
> +	if (!res)
> +		return -ENOMEM;
>  
>  	pgmap = kzalloc(sizeof(*pgmap), GFP_KERNEL);
>  	if (!pgmap)
> -		return -ENOMEM;
> +		goto err_pgmap;
>  
>  	pgmap->type = MEMORY_DEVICE_GENERIC;


Can you move these last 5 lines ...


> -	pgmap->res.name = "Xen scratch";
> -	pgmap->res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> +	res->name = "Xen scratch";
> +	res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
>  
> -	ret = allocate_resource(&iomem_resource, &pgmap->res,
> +	ret = allocate_resource(&iomem_resource, res,
>  				alloc_pages * PAGE_SIZE, 0, -1,
>  				PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL);
>  	if (ret < 0) {
>  		pr_err("Cannot allocate new IOMEM resource\n");
> -		kfree(pgmap);
> -		return ret;
> +		goto err_resource;
>  	}
>  


... here, so that we deal with pgmap in the same place? The diff will be slightly larger but the code will read better I think.


-boris


> +	pgmap->range = (struct range) {
> +		.start = res->start,
> +		.end = res->end,
> +	};
> +	pgmap->owner = res;
> +
>  #ifdef CONFIG_XEN_HAVE_PVMMU
>          /*
>           * memremap will build page tables for the new memory so