[PATCH] drivers/virt: use get_user_pages_unlocked()

[PATCH] drivers/virt: use get_user_pages_unlocked()

[Lorenzo Stoakes]

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@gmail.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

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Re: [PATCH] drivers/virt: use get_user_pages_unlocked()

[Lorenzo Stoakes]

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@gmail.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@gmail.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

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Re: [PATCH] drivers/virt: use get_user_pages_unlocked()

[Michal Hocko]

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

> On 1 November 2016 at 19:43, Lorenzo Stoakes <lstoakes@gmail.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@gmail.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

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Re: [PATCH] drivers/virt: use get_user_pages_unlocked()

[Lorenzo Stoakes]

On 3 January 2017 at 21:36, Michal Hocko <mhocko@kernel.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@gmail.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@gmail.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

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