linux-kernel - Re: [PATCH 04/13] misc/habana: Use FOLL

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Date:   Wed, 7 Oct 2020 13:46:04 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     Daniel Vetter <daniel.vetter@...ll.ch>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
CC:     <kvm@...r.kernel.org>, <linux-mm@...ck.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-samsung-soc@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <linux-s390@...r.kernel.org>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jérôme Glisse <jglisse@...hat.com>,
        Jan Kara <jack@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Oded Gabbay <oded.gabbay@...il.com>,
        "Omer Shpigelman" <oshpigelman@...ana.ai>,
        Ofir Bitton <obitton@...ana.ai>,
        "Tomer Tayar" <ttayar@...ana.ai>,
        Moti Haimovski <mhaimovski@...ana.ai>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        Pawel Piskorski <ppiskorski@...ana.ai>
Subject: Re: [PATCH 04/13] misc/habana: Use FOLL_LONGTERM for userptr

On 10/7/20 9:44 AM, Daniel Vetter wrote:
> These are persistent, not just for the duration of a dma operation.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
> Cc: Jason Gunthorpe <jgg@...pe.ca>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: John Hubbard <jhubbard@...dia.com>
> Cc: Jérôme Glisse <jglisse@...hat.com>
> Cc: Jan Kara <jack@...e.cz>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: linux-mm@...ck.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-samsung-soc@...r.kernel.org
> Cc: linux-media@...r.kernel.org
> Cc: Oded Gabbay <oded.gabbay@...il.com>
> Cc: Omer Shpigelman <oshpigelman@...ana.ai>
> Cc: Ofir Bitton <obitton@...ana.ai>
> Cc: Tomer Tayar <ttayar@...ana.ai>
> Cc: Moti Haimovski <mhaimovski@...ana.ai>
> Cc: Daniel Vetter <daniel.vetter@...ll.ch>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Pawel Piskorski <ppiskorski@...ana.ai>
> ---
>   drivers/misc/habanalabs/common/memory.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/habanalabs/common/memory.c b/drivers/misc/habanalabs/common/memory.c
> index ef89cfa2f95a..94bef8faa82a 100644
> --- a/drivers/misc/habanalabs/common/memory.c
> +++ b/drivers/misc/habanalabs/common/memory.c
> @@ -1288,7 +1288,8 @@ static int get_user_memory(struct hl_device *hdev, u64 addr, u64 size,
>   		return -ENOMEM;
>   	}
>   
> -	rc = pin_user_pages_fast(start, npages, FOLL_FORCE | FOLL_WRITE,
> +	rc = pin_user_pages_fast(start, npages,
> +				 FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM,
>   				 userptr->pages);
>   
>   	if (rc != npages) {
> 

Again, from a pin_user_pages_fast() point of view, and not being at all familiar
with the habana driver (but their use of this really does seem clearly _LONGTERM!):

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

thanks,
-- 
John Hubbard
NVIDIA