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

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Message-ID: <CAA5enKbdH_oo7U_RjFA3ZipHL8QSnE+oAi9McFb7z7ZHrcNERA@mail.gmail.com>
Date:   Mon, 20 Feb 2017 18:34:36 +0000
From:   Lorenzo Stoakes <lstoakes@...il.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Kumar Gala <galak@...nel.crashing.org>,
        Mihai Caraman <mihai.caraman@...escale.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] drivers/virt: use get_user_pages_unlocked()

On 3 January 2017 at 21:36, Michal Hocko <mhocko@...nel.org> wrote:
> On Tue 03-01-17 21:14:20, Lorenzo Stoakes wrote:
>> 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.
>
> Maybe Andrew can pick it up?
> http://lkml.kernel.org/r/20161101194332.23961-1-lstoakes@gmail.com
>

Hi all, since the merge window has opened thought I'd give another
gentle nudge on this - Andrew, are you ok to pick this up? For
convenience the raw patch is at
https://marc.info/?l=linux-mm&m=147802941732512&q=raw I've checked and
it still applies. Let me know if you want me to simply resend this or
if there is anything else I can do to nudge this along!

Thanks, Lorenzo

>> 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
>
> --
> Michal Hocko
> SUSE Labs



-- 
Lorenzo Stoakes
https://ljs.io