[PATCH v4] staging: kpc2000: Convert put_page to put_user_page*()

[PATCH v4] staging: kpc2000: Convert put_page to put_user_page*()

[Bharath Vedartham]

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d ("mm: introduce put_user_page*(), placeholder versions").

Cc: Ira Weiny <ira.weiny@intel.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matt Sickler <Matt.Sickler@daktronics.com>
Cc: devel@driverdev.osuosl.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
---
Changes since v1
       - Improved changelog by John's suggestion.
       - Moved logic to dirty pages below sg_dma_unmap
       and removed PageReserved check.
Changes since v2
       - Added back PageResevered check as suggested by John Hubbard.
Changes since v3
       - Changed the commit log as suggested by John.
       - Added John's Reviewed-By tag

---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index 6166587..75ad263 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -198,9 +198,7 @@ int  kpc_dma_transfer(struct dev_private_data *priv, struct kiocb *kcb, unsigned
 	sg_free_table(&acd->sgt);
  err_dma_map_sg:
  err_alloc_sg_table:
-	for (i = 0 ; i < acd->page_count ; i++){
-		put_page(acd->user_pages[i]);
-	}
+	put_user_pages(acd->user_pages, acd->page_count);
  err_get_user_pages:
 	kfree(acd->user_pages);
  err_alloc_userpages:
@@ -221,16 +219,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
 	
 	dev_dbg(&acd->ldev->pldev->dev, "transfer_complete_cb(acd = [%p])\n", acd);
 	
-	for (i = 0 ; i < acd->page_count ; i++){
-		if (!PageReserved(acd->user_pages[i])){
-			set_page_dirty(acd->user_pages[i]);
-		}
-	}
-	
 	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
 	
-	for (i = 0 ; i < acd->page_count ; i++){
-		put_page(acd->user_pages[i]);
+	for (i = 0; i < acd->page_count; i++) {
+		if (!PageReserved(acd->user_pages[i]))
+			put_user_pages_dirty(&acd->user_pages[i], 1);
+		else
+			put_user_page(acd->user_pages[i]);
 	}
 	
 	sg_free_table(&acd->sgt);
-- 
2.7.4

[PATCH v4] staging: kpc2000: Convert put_page to put_user_page*()

[Bharath Vedartham]

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d ("mm: introduce put_user_page*(), placeholder versions").

Cc: Ira Weiny <ira.weiny at intel.com>
Cc: John Hubbard <jhubbard at nvidia.com>
Cc: J?r?me Glisse <jglisse at redhat.com>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Matt Sickler <Matt.Sickler at daktronics.com>
Cc: devel at driverdev.osuosl.org
Cc: linux-kernel at vger.kernel.org
Cc: linux-mm at kvack.org
Reviewed-by: John Hubbard <jhubbard at nvidia.com>
Signed-off-by: Bharath Vedartham <linux.bhar at gmail.com>
---
Changes since v1
       - Improved changelog by John's suggestion.
       - Moved logic to dirty pages below sg_dma_unmap
       and removed PageReserved check.
Changes since v2
       - Added back PageResevered check as suggested by John Hubbard.
Changes since v3
       - Changed the commit log as suggested by John.
       - Added John's Reviewed-By tag

---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index 6166587..75ad263 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -198,9 +198,7 @@ int  kpc_dma_transfer(struct dev_private_data *priv, struct kiocb *kcb, unsigned
 	sg_free_table(&acd->sgt);
  err_dma_map_sg:
  err_alloc_sg_table:
-	for (i = 0 ; i < acd->page_count ; i++){
-		put_page(acd->user_pages[i]);
-	}
+	put_user_pages(acd->user_pages, acd->page_count);
  err_get_user_pages:
 	kfree(acd->user_pages);
  err_alloc_userpages:
@@ -221,16 +219,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
 	
 	dev_dbg(&acd->ldev->pldev->dev, "transfer_complete_cb(acd = [%p])\n", acd);
 	
-	for (i = 0 ; i < acd->page_count ; i++){
-		if (!PageReserved(acd->user_pages[i])){
-			set_page_dirty(acd->user_pages[i]);
-		}
-	}
-	
 	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
 	
-	for (i = 0 ; i < acd->page_count ; i++){
-		put_page(acd->user_pages[i]);
+	for (i = 0; i < acd->page_count; i++) {
+		if (!PageReserved(acd->user_pages[i]))
+			put_user_pages_dirty(&acd->user_pages[i], 1);
+		else
+			put_user_page(acd->user_pages[i]);
 	}
 	
 	sg_free_table(&acd->sgt);
-- 
2.7.4

Re: [PATCH v4] staging: kpc2000: Convert put_page to put_user_page*()

[Greg KH]

On Sat, Jul 20, 2019 at 11:02:14PM +0530, Bharath Vedartham wrote:
> For pages that were retained via get_user_pages*(), release those pages
> via the new put_user_page*() routines, instead of via put_page().
> 
> This is part a tree-wide conversion, as described in commit fc1d8e7cca2d ("mm: introduce put_user_page*(), placeholder versions").

Please line-wrap this line.

> 
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Jérôme Glisse <jglisse@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Matt Sickler <Matt.Sickler@daktronics.com>
> Cc: devel@driverdev.osuosl.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-mm@kvack.org
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
> ---
> Changes since v1
>        - Improved changelog by John's suggestion.
>        - Moved logic to dirty pages below sg_dma_unmap
>        and removed PageReserved check.
> Changes since v2
>        - Added back PageResevered check as suggested by John Hubbard.
> Changes since v3
>        - Changed the commit log as suggested by John.
>        - Added John's Reviewed-By tag
> 
> ---
>  drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
> index 6166587..75ad263 100644
> --- a/drivers/staging/kpc2000/kpc_dma/fileops.c
> +++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
> @@ -198,9 +198,7 @@ int  kpc_dma_transfer(struct dev_private_data *priv, struct kiocb *kcb, unsigned
>  	sg_free_table(&acd->sgt);
>   err_dma_map_sg:
>   err_alloc_sg_table:
> -	for (i = 0 ; i < acd->page_count ; i++){
> -		put_page(acd->user_pages[i]);
> -	}
> +	put_user_pages(acd->user_pages, acd->page_count);
>   err_get_user_pages:
>  	kfree(acd->user_pages);
>   err_alloc_userpages:
> @@ -221,16 +219,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
>  	
>  	dev_dbg(&acd->ldev->pldev->dev, "transfer_complete_cb(acd = [%p])\n", acd);
>  	
> -	for (i = 0 ; i < acd->page_count ; i++){
> -		if (!PageReserved(acd->user_pages[i])){
> -			set_page_dirty(acd->user_pages[i]);
> -		}
> -	}
> -	
>  	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
>  	
> -	for (i = 0 ; i < acd->page_count ; i++){
> -		put_page(acd->user_pages[i]);
> +	for (i = 0; i < acd->page_count; i++) {
> +		if (!PageReserved(acd->user_pages[i]))
> +			put_user_pages_dirty(&acd->user_pages[i], 1);
> +		else
> +			put_user_page(acd->user_pages[i]);
>  	}
>  	
>  	sg_free_table(&acd->sgt);
> -- 
> 2.7.4

This patch can not be applied at all :(

Can you redo it against the latest staging-next branch and resend?

thanks,

greg k-h

Re: [PATCH v4] staging: kpc2000: Convert put_page to put_user_page*()

[Greg KH]

On Sat, Jul 20, 2019 at 11:02:14PM +0530, Bharath Vedartham wrote:
> For pages that were retained via get_user_pages*(), release those pages
> via the new put_user_page*() routines, instead of via put_page().
> 
> This is part a tree-wide conversion, as described in commit fc1d8e7cca2d ("mm: introduce put_user_page*(), placeholder versions").

Please line-wrap this line.

> 
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Jérôme Glisse <jglisse@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Matt Sickler <Matt.Sickler@daktronics.com>
> Cc: devel@driverdev.osuosl.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-mm@kvack.org
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
> ---
> Changes since v1
>        - Improved changelog by John's suggestion.
>        - Moved logic to dirty pages below sg_dma_unmap
>        and removed PageReserved check.
> Changes since v2
>        - Added back PageResevered check as suggested by John Hubbard.
> Changes since v3
>        - Changed the commit log as suggested by John.
>        - Added John's Reviewed-By tag
> 
> ---
>  drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
> index 6166587..75ad263 100644
> --- a/drivers/staging/kpc2000/kpc_dma/fileops.c
> +++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
> @@ -198,9 +198,7 @@ int  kpc_dma_transfer(struct dev_private_data *priv, struct kiocb *kcb, unsigned
>  	sg_free_table(&acd->sgt);
>   err_dma_map_sg:
>   err_alloc_sg_table:
> -	for (i = 0 ; i < acd->page_count ; i++){
> -		put_page(acd->user_pages[i]);
> -	}
> +	put_user_pages(acd->user_pages, acd->page_count);
>   err_get_user_pages:
>  	kfree(acd->user_pages);
>   err_alloc_userpages:
> @@ -221,16 +219,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
>  	
>  	dev_dbg(&acd->ldev->pldev->dev, "transfer_complete_cb(acd = [%p])\n", acd);
>  	
> -	for (i = 0 ; i < acd->page_count ; i++){
> -		if (!PageReserved(acd->user_pages[i])){
> -			set_page_dirty(acd->user_pages[i]);
> -		}
> -	}
> -	
>  	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
>  	
> -	for (i = 0 ; i < acd->page_count ; i++){
> -		put_page(acd->user_pages[i]);
> +	for (i = 0; i < acd->page_count; i++) {
> +		if (!PageReserved(acd->user_pages[i]))
> +			put_user_pages_dirty(&acd->user_pages[i], 1);
> +		else
> +			put_user_page(acd->user_pages[i]);
>  	}
>  	
>  	sg_free_table(&acd->sgt);
> -- 
> 2.7.4

This patch can not be applied at all :(

Can you redo it against the latest staging-next branch and resend?

thanks,

greg k-h

Re: [PATCH v4] staging: kpc2000: Convert put_page to put_user_page*()

[Bharath Vedartham]

On Thu, Jul 25, 2019 at 09:46:34AM +0200, Greg KH wrote:
> On Sat, Jul 20, 2019 at 11:02:14PM +0530, Bharath Vedartham wrote:
> > For pages that were retained via get_user_pages*(), release those pages
> > via the new put_user_page*() routines, instead of via put_page().
> > 
> > This is part a tree-wide conversion, as described in commit fc1d8e7cca2d ("mm: introduce put_user_page*(), placeholder versions").
> 
> Please line-wrap this line.
> 
> > 
> > Cc: Ira Weiny <ira.weiny@intel.com>
> > Cc: John Hubbard <jhubbard@nvidia.com>
> > Cc: Jérôme Glisse <jglisse@redhat.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: Matt Sickler <Matt.Sickler@daktronics.com>
> > Cc: devel@driverdev.osuosl.org
> > Cc: linux-kernel@vger.kernel.org
> > Cc: linux-mm@kvack.org
> > Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> > Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
> > ---
> > Changes since v1
> >        - Improved changelog by John's suggestion.
> >        - Moved logic to dirty pages below sg_dma_unmap
> >        and removed PageReserved check.
> > Changes since v2
> >        - Added back PageResevered check as suggested by John Hubbard.
> > Changes since v3
> >        - Changed the commit log as suggested by John.
> >        - Added John's Reviewed-By tag
> > 
> > ---
> >  drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
> >  1 file changed, 6 insertions(+), 11 deletions(-)
> > 
> > diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
> > index 6166587..75ad263 100644
> > --- a/drivers/staging/kpc2000/kpc_dma/fileops.c
> > +++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
> > @@ -198,9 +198,7 @@ int  kpc_dma_transfer(struct dev_private_data *priv, struct kiocb *kcb, unsigned
> >  	sg_free_table(&acd->sgt);
> >   err_dma_map_sg:
> >   err_alloc_sg_table:
> > -	for (i = 0 ; i < acd->page_count ; i++){
> > -		put_page(acd->user_pages[i]);
> > -	}
> > +	put_user_pages(acd->user_pages, acd->page_count);
> >   err_get_user_pages:
> >  	kfree(acd->user_pages);
> >   err_alloc_userpages:
> > @@ -221,16 +219,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
> >  	
> >  	dev_dbg(&acd->ldev->pldev->dev, "transfer_complete_cb(acd = [%p])\n", acd);
> >  	
> > -	for (i = 0 ; i < acd->page_count ; i++){
> > -		if (!PageReserved(acd->user_pages[i])){
> > -			set_page_dirty(acd->user_pages[i]);
> > -		}
> > -	}
> > -	
> >  	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
> >  	
> > -	for (i = 0 ; i < acd->page_count ; i++){
> > -		put_page(acd->user_pages[i]);
> > +	for (i = 0; i < acd->page_count; i++) {
> > +		if (!PageReserved(acd->user_pages[i]))
> > +			put_user_pages_dirty(&acd->user_pages[i], 1);
> > +		else
> > +			put_user_page(acd->user_pages[i]);
> >  	}
> >  	
> >  	sg_free_table(&acd->sgt);
> > -- 
> > 2.7.4
> 
> This patch can not be applied at all :(
> 
> Can you redo it against the latest staging-next branch and resend?
> 
> thanks,
Yup. Will do that!
> greg k-h

Re: [PATCH v4] staging: kpc2000: Convert put_page() to put_user_page*()

[John Hubbard]

On 7/25/19 5:44 AM, Bharath Vedartham wrote:
> For pages that were retained via get_user_pages*(), release those pages
> via the new put_user_page*() routines, instead of via put_page().
> 
> This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
> ("mm: introduce put_user_page*(), placeholder versions").
> 

Hi Bharath,

If you like, I could re-post your patch here, modified slightly, as part of
the next version of the miscellaneous call site conversion series [1].

As part of that, we should change this to use put_user_pages_dirty_lock() 
(see below).


> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Jérôme Glisse <jglisse@redhat.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Matt Sickler <Matt.Sickler@daktronics.com>
> Cc: devel@driverdev.osuosl.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-mm@kvack.org
> Reviewed-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
> ---
> Changes since v1
>         - Improved changelog by John's suggestion.
>         - Moved logic to dirty pages below sg_dma_unmap
>          and removed PageReserved check.
> Changes since v2
>         - Added back PageResevered check as
>         suggested by John Hubbard.
> Changes since v3
>         - Changed the changelog as suggested by John.
>         - Added John's Reviewed-By tag.
> Changes since v4
>         - Rebased the patch on the staging tree.
>         - Improved commit log by fixing a line wrap.
> ---
>  drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
> index 48ca88b..f15e292 100644
> --- a/drivers/staging/kpc2000/kpc_dma/fileops.c
> +++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
> @@ -190,9 +190,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
>  	sg_free_table(&acd->sgt);
>   err_dma_map_sg:
>   err_alloc_sg_table:
> -	for (i = 0 ; i < acd->page_count ; i++) {
> -		put_page(acd->user_pages[i]);
> -	}
> +	put_user_pages(acd->user_pages, acd->page_count);
>   err_get_user_pages:
>  	kfree(acd->user_pages);
>   err_alloc_userpages:
> @@ -211,16 +209,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
>  	BUG_ON(acd->ldev == NULL);
>  	BUG_ON(acd->ldev->pldev == NULL);
>  
> -	for (i = 0 ; i < acd->page_count ; i++) {
> -		if (!PageReserved(acd->user_pages[i])) {
> -			set_page_dirty(acd->user_pages[i]);
> -		}
> -	}
> -
>  	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
>  
> -	for (i = 0 ; i < acd->page_count ; i++) {
> -		put_page(acd->user_pages[i]);
> +	for (i = 0; i < acd->page_count; i++) {
> +		if (!PageReserved(acd->user_pages[i]))
> +			put_user_pages_dirty(&acd->user_pages[i], 1);


This would change to:
			put_user_pages_dirty_lock(&acd->user_pages[i], 1, true);


...and we'd add this blurb (this time with CH's name spelled properly) to 
the commit description:

Note that this effectively changes the code's behavior in
qp_release_pages(): it now ultimately calls set_page_dirty_lock(),
instead of set_page_dirty(). This is probably more accurate.

As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
dealing with a file backed page where we have reference on the inode it
hangs off." [1]

[1] https://lore.kernel.org/r/20190723153640.GB720@lst.de

Also, future: I don't know the driver well enough to say, but maybe "true" 
could be replaced by "acd->ldev->dir == DMA_FROM_DEVICE", there, but that
would be a separate patch.


thanks,
-- 
John Hubbard
NVIDIA


> +		else
> +			put_user_page(acd->user_pages[i]);
>  	}
>  
>  	sg_free_table(&acd->sgt);
> 

[PATCH v4] staging: kpc2000: Convert put_page() to put_user_page*()

[John Hubbard]

On 7/25/19 5:44 AM, Bharath Vedartham wrote:
> For pages that were retained via get_user_pages*(), release those pages
> via the new put_user_page*() routines, instead of via put_page().
> 
> This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
> ("mm: introduce put_user_page*(), placeholder versions").
> 

Hi Bharath,

If you like, I could re-post your patch here, modified slightly, as part of
the next version of the miscellaneous call site conversion series [1].

As part of that, we should change this to use put_user_pages_dirty_lock() 
(see below).


> Cc: Ira Weiny <ira.weiny at intel.com>
> Cc: John Hubbard <jhubbard at nvidia.com>
> Cc: J?r?me Glisse <jglisse at redhat.com>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> Cc: Matt Sickler <Matt.Sickler at daktronics.com>
> Cc: devel at driverdev.osuosl.org
> Cc: linux-kernel at vger.kernel.org
> Cc: linux-mm at kvack.org
> Reviewed-by: John Hubbard <jhubbard at nvidia.com>
> Signed-off-by: Bharath Vedartham <linux.bhar at gmail.com>
> ---
> Changes since v1
>         - Improved changelog by John's suggestion.
>         - Moved logic to dirty pages below sg_dma_unmap
>          and removed PageReserved check.
> Changes since v2
>         - Added back PageResevered check as
>         suggested by John Hubbard.
> Changes since v3
>         - Changed the changelog as suggested by John.
>         - Added John's Reviewed-By tag.
> Changes since v4
>         - Rebased the patch on the staging tree.
>         - Improved commit log by fixing a line wrap.
> ---
>  drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
>  1 file changed, 6 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
> index 48ca88b..f15e292 100644
> --- a/drivers/staging/kpc2000/kpc_dma/fileops.c
> +++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
> @@ -190,9 +190,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
>  	sg_free_table(&acd->sgt);
>   err_dma_map_sg:
>   err_alloc_sg_table:
> -	for (i = 0 ; i < acd->page_count ; i++) {
> -		put_page(acd->user_pages[i]);
> -	}
> +	put_user_pages(acd->user_pages, acd->page_count);
>   err_get_user_pages:
>  	kfree(acd->user_pages);
>   err_alloc_userpages:
> @@ -211,16 +209,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
>  	BUG_ON(acd->ldev == NULL);
>  	BUG_ON(acd->ldev->pldev == NULL);
>  
> -	for (i = 0 ; i < acd->page_count ; i++) {
> -		if (!PageReserved(acd->user_pages[i])) {
> -			set_page_dirty(acd->user_pages[i]);
> -		}
> -	}
> -
>  	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
>  
> -	for (i = 0 ; i < acd->page_count ; i++) {
> -		put_page(acd->user_pages[i]);
> +	for (i = 0; i < acd->page_count; i++) {
> +		if (!PageReserved(acd->user_pages[i]))
> +			put_user_pages_dirty(&acd->user_pages[i], 1);


This would change to:
			put_user_pages_dirty_lock(&acd->user_pages[i], 1, true);


...and we'd add this blurb (this time with CH's name spelled properly) to 
the commit description:

Note that this effectively changes the code's behavior in
qp_release_pages(): it now ultimately calls set_page_dirty_lock(),
instead of set_page_dirty(). This is probably more accurate.

As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
dealing with a file backed page where we have reference on the inode it
hangs off." [1]

[1] https://lore.kernel.org/r/20190723153640.GB720 at lst.de

Also, future: I don't know the driver well enough to say, but maybe "true" 
could be replaced by "acd->ldev->dir == DMA_FROM_DEVICE", there, but that
would be a separate patch.


thanks,
-- 
John Hubbard
NVIDIA


> +		else
> +			put_user_page(acd->user_pages[i]);
>  	}
>  
>  	sg_free_table(&acd->sgt);
> 

[PATCH v4] staging: kpc2000: Convert put_page() to put_user_page*()

[Bharath Vedartham]

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
("mm: introduce put_user_page*(), placeholder versions").

Cc: Ira Weiny <ira.weiny@intel.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matt Sickler <Matt.Sickler@daktronics.com>
Cc: devel@driverdev.osuosl.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
---
Changes since v1
        - Improved changelog by John's suggestion.
        - Moved logic to dirty pages below sg_dma_unmap
         and removed PageReserved check.
Changes since v2
        - Added back PageResevered check as
        suggested by John Hubbard.
Changes since v3
        - Changed the changelog as suggested by John.
        - Added John's Reviewed-By tag.
Changes since v4
        - Rebased the patch on the staging tree.
        - Improved commit log by fixing a line wrap.
---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index 48ca88b..f15e292 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -190,9 +190,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 	sg_free_table(&acd->sgt);
  err_dma_map_sg:
  err_alloc_sg_table:
-	for (i = 0 ; i < acd->page_count ; i++) {
-		put_page(acd->user_pages[i]);
-	}
+	put_user_pages(acd->user_pages, acd->page_count);
  err_get_user_pages:
 	kfree(acd->user_pages);
  err_alloc_userpages:
@@ -211,16 +209,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
 	BUG_ON(acd->ldev == NULL);
 	BUG_ON(acd->ldev->pldev == NULL);
 
-	for (i = 0 ; i < acd->page_count ; i++) {
-		if (!PageReserved(acd->user_pages[i])) {
-			set_page_dirty(acd->user_pages[i]);
-		}
-	}
-
 	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
 
-	for (i = 0 ; i < acd->page_count ; i++) {
-		put_page(acd->user_pages[i]);
+	for (i = 0; i < acd->page_count; i++) {
+		if (!PageReserved(acd->user_pages[i]))
+			put_user_pages_dirty(&acd->user_pages[i], 1);
+		else
+			put_user_page(acd->user_pages[i]);
 	}
 
 	sg_free_table(&acd->sgt);
-- 
2.7.4

[PATCH v4] staging: kpc2000: Convert put_page() to put_user_page*()

[Bharath Vedartham]

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
("mm: introduce put_user_page*(), placeholder versions").

Cc: Ira Weiny <ira.weiny@intel.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Matt Sickler <Matt.Sickler@daktronics.com>
Cc: devel@driverdev.osuosl.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Bharath Vedartham <linux.bhar@gmail.com>
---
Changes since v1
        - Improved changelog by John's suggestion.
        - Moved logic to dirty pages below sg_dma_unmap
         and removed PageReserved check.
Changes since v2
        - Added back PageResevered check as
        suggested by John Hubbard.
Changes since v3
        - Changed the changelog as suggested by John.
        - Added John's Reviewed-By tag.
Changes since v4
        - Rebased the patch on the staging tree.
        - Improved commit log by fixing a line wrap.
---
 drivers/staging/kpc2000/kpc_dma/fileops.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/staging/kpc2000/kpc_dma/fileops.c b/drivers/staging/kpc2000/kpc_dma/fileops.c
index 48ca88b..f15e292 100644
--- a/drivers/staging/kpc2000/kpc_dma/fileops.c
+++ b/drivers/staging/kpc2000/kpc_dma/fileops.c
@@ -190,9 +190,7 @@ static int kpc_dma_transfer(struct dev_private_data *priv,
 	sg_free_table(&acd->sgt);
  err_dma_map_sg:
  err_alloc_sg_table:
-	for (i = 0 ; i < acd->page_count ; i++) {
-		put_page(acd->user_pages[i]);
-	}
+	put_user_pages(acd->user_pages, acd->page_count);
  err_get_user_pages:
 	kfree(acd->user_pages);
  err_alloc_userpages:
@@ -211,16 +209,13 @@ void  transfer_complete_cb(struct aio_cb_data *acd, size_t xfr_count, u32 flags)
 	BUG_ON(acd->ldev == NULL);
 	BUG_ON(acd->ldev->pldev == NULL);
 
-	for (i = 0 ; i < acd->page_count ; i++) {
-		if (!PageReserved(acd->user_pages[i])) {
-			set_page_dirty(acd->user_pages[i]);
-		}
-	}
-
 	dma_unmap_sg(&acd->ldev->pldev->dev, acd->sgt.sgl, acd->sgt.nents, acd->ldev->dir);
 
-	for (i = 0 ; i < acd->page_count ; i++) {
-		put_page(acd->user_pages[i]);
+	for (i = 0; i < acd->page_count; i++) {
+		if (!PageReserved(acd->user_pages[i]))
+			put_user_pages_dirty(&acd->user_pages[i], 1);
+		else
+			put_user_page(acd->user_pages[i]);
 	}
 
 	sg_free_table(&acd->sgt);
-- 
2.7.4

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