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Subject: Re: [PATCH 09/15] mm/hmm/devmem: device memory hotplug using
 ZONE_DEVICE v6
References: <20170628180047.5386-1-jglisse@redhat.com>
 <20170628180047.5386-10-jglisse@redhat.com>
From: Evgeny Baskakov <ebaskakov@nvidia.com>
Message-ID: <be0503da-f1c4-f3c2-dace-6a9aa02c3186@nvidia.com>
Date: Tue, 18 Jul 2017 14:41:01 -0700
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In-Reply-To: <20170628180047.5386-10-jglisse@redhat.com>
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To: =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc: John Hubbard <jhubbard@nvidia.com>, Dan Williams <dan.j.williams@intel.com>, David Nellans <dnellans@nvidia.com>, Mark Hairgrove <mhairgrove@nvidia.com>, Sherry Cheung <SCheung@nvidia.com>, Subhash Gutti <sgutti@nvidia.com>

On 6/28/17 11:00 AM, J=C3=A9r=C3=B4me Glisse wrote:

> +/*
> + * struct hmm_devmem_ops - callback for ZONE_DEVICE memory events
> + *
> + * @free: call when refcount on page reach 1 and thus is no longer use
> + * @fault: call when there is a page fault to unaddressable memory
> + */
> +struct hmm_devmem_ops {
> +	void (*free)(struct hmm_devmem *devmem, struct page *page);
> +	int (*fault)(struct hmm_devmem *devmem,
> +		     struct vm_area_struct *vma,
> +		     unsigned long addr,
> +		     struct page *page,
> +		     unsigned int flags,
> +		     pmd_t *pmdp);
> +};
>

Hi Jerome,

As discussed, could you please add detailed documentation for these=20
callbacks?

Specifically, for the 'fault' callback it is important to clarify the=20
meaning of each of its parameters and the return value (which error=20
codes are expected to be returned from it).

Thanks!

--=20
Evgeny Baskakov
NVIDIA

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