linux-kernel - Re: [PATCH 07/14] mm/hmm: use uint64_t for HMM pfn instead of defining hmm_pfn

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Message-ID: <e20e4e55-c99b-03c2-0bcf-4167d583dcbe@nvidia.com>
Date:   Fri, 16 Mar 2018 20:59:49 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     <jglisse@...hat.com>, <linux-mm@...ck.org>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        <linux-kernel@...r.kernel.org>,
        Evgeny Baskakov <ebaskakov@...dia.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Mark Hairgrove <mhairgrove@...dia.com>
Subject: Re: [PATCH 07/14] mm/hmm: use uint64_t for HMM pfn instead of
 defining hmm_pfn_t to ulong

On 03/16/2018 12:14 PM, jglisse@...hat.com wrote:
> From: Jérôme Glisse <jglisse@...hat.com>
> 

Hi Jerome,

This one looks great. A couple of trivial typo fixes are listed below.

You can add:

Reviewed-by: John Hubbard <jhubbard@...dia.com>

> All device driver we care about are using 64bits page table entry. In
> order to match this and to avoid useless define convert all HMM pfn to
> directly use uint64_t. It is a first step on the road to allow driver
> to directly use pfn value return by HMM (saving memory and CPU cycles
> use for convertion between the two).

  used for conversion
> 
> Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
> Cc: Evgeny Baskakov <ebaskakov@...dia.com>
> Cc: Ralph Campbell <rcampbell@...dia.com>
> Cc: Mark Hairgrove <mhairgrove@...dia.com>
> Cc: John Hubbard <jhubbard@...dia.com>
> ---
>  include/linux/hmm.h | 46 +++++++++++++++++++++-------------------------
>  mm/hmm.c            | 26 +++++++++++++-------------
>  2 files changed, 34 insertions(+), 38 deletions(-)
> 

<snip>

> @@ -104,14 +100,14 @@ typedef unsigned long hmm_pfn_t;
>  #define HMM_PFN_SHIFT 6
>  
>  /*
> - * hmm_pfn_t_to_page() - return struct page pointed to by a valid hmm_pfn_t
> - * @pfn: hmm_pfn_t to convert to struct page
> - * Returns: struct page pointer if pfn is a valid hmm_pfn_t, NULL otherwise
> + * hmm_pfn_to_page() - return struct page pointed to by a valid HMM pfn
> + * @pfn: HMM pfn value to get corresponding struct page from
> + * Returns: struct page pointer if pfn is a valid HMM pfn, NULL otherwise
>   *
> - * If the hmm_pfn_t is valid (ie valid flag set) then return the struct page
> - * matching the pfn value stored in the hmm_pfn_t. Otherwise return NULL.
> + * If the uint64_t is valid (ie valid flag set) then return the struct page

      If the HMM pfn is valid

<snip>

>  
> @@ -634,8 +634,8 @@ EXPORT_SYMBOL(hmm_vma_range_done);
>   * This is similar to a regular CPU page fault except that it will not trigger
>   * any memory migration if the memory being faulted is not accessible by CPUs.
>   *
> - * On error, for one virtual address in the range, the function will set the
> - * hmm_pfn_t error flag for the corresponding pfn entry.
> + * On error, for one virtual address in the range, the function will mark the
> + * correspond HMM pfn entry with error flag.

      corresponding HMM pfn entry with an error flag.

thanks,
-- 
John Hubbard
NVIDIA