linux-kernel - Re: [PATCH] drivers/virt: use get_user_pages

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Date:   Tue, 3 Jan 2017 21:14:20 +0000
From:   Lorenzo Stoakes <lstoakes@...il.com>
To:     linux-mm <linux-mm@...ck.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Michal Hocko <mhocko@...nel.org>,
        Kumar Gala <galak@...nel.crashing.org>,
        Mihai Caraman <mihai.caraman@...escale.com>,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] drivers/virt: use get_user_pages_unlocked()

Just a gentle ping on this :) I think this might be a slightly
abandoned corner of the kernel so not sure who else to ping to get
this moving.

On 1 November 2016 at 19:43, Lorenzo Stoakes <lstoakes@...il.com> wrote:
> Moving from get_user_pages() to get_user_pages_unlocked() simplifies the code
> and takes advantage of VM_FAULT_RETRY functionality when faulting in pages.
>
> Signed-off-by: Lorenzo Stoakes <lstoakes@...il.com>
> ---
>  drivers/virt/fsl_hypervisor.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/virt/fsl_hypervisor.c b/drivers/virt/fsl_hypervisor.c
> index 150ce2a..d3eca87 100644
> --- a/drivers/virt/fsl_hypervisor.c
> +++ b/drivers/virt/fsl_hypervisor.c
> @@ -243,11 +243,8 @@ static long ioctl_memcpy(struct fsl_hv_ioctl_memcpy __user *p)
>         sg_list = PTR_ALIGN(sg_list_unaligned, sizeof(struct fh_sg_list));
>
>         /* Get the physical addresses of the source buffer */
> -       down_read(&current->mm->mmap_sem);
> -       num_pinned = get_user_pages(param.local_vaddr - lb_offset,
> -               num_pages, (param.source == -1) ? 0 : FOLL_WRITE,
> -               pages, NULL);
> -       up_read(&current->mm->mmap_sem);
> +       num_pinned = get_user_pages_unlocked(param.local_vaddr - lb_offset,
> +               num_pages, pages, (param.source == -1) ? 0 : FOLL_WRITE);
>
>         if (num_pinned != num_pages) {
>                 /* get_user_pages() failed */
> --
> 2.10.2
>



-- 
Lorenzo Stoakes
https://ljs.io