[PATCH 0/4] Remove get_kernel_pages()

[PATCH 0/4] Remove get_kernel_pages()

[ira.weiny]

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From: Ira Weiny <ira.weiny@intel.com>

get_kernel_pages() only had one caller [shm_get_kernel_pages()] which did not
need the functionality it provided.  Furthermore, it called kmap_to_page()
which we are looking to removed.

Alter shm_get_kernel_pages() to no longer call get_kernel_pages() and remove
get_kernel_pages().  Along the way it was noted that shm_get_kernel_pages()
does not have any need to support vmalloc'ed addresses either.  Remove that
functionality to clean up the logic.

This series also fixes and uses is_kmap_addr().

Ira Weiny (4):
  highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings
  tee: Remove vmalloc page support
  tee: Remove call to get_kernel_pages()
  mm: Remove get_kernel_pages()

 drivers/tee/tee_shm.c            | 41 ++++++++++++--------------------
 include/linux/highmem-internal.h |  5 +++-
 include/linux/mm.h               |  2 --
 mm/swap.c                        | 30 -----------------------
 4 files changed, 19 insertions(+), 59 deletions(-)


base-commit: 274d7803837da78dfc911bcda0d593412676fc20
-- 
2.37.2

[PATCH 1/4] highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings

[ira.weiny]

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From: Ira Weiny <ira.weiny@intel.com>

is_kmap_addr() is only looking at the kmap() address range which may
cause check_heap_object() to miss checking an overflow on a
kmap_local_page() page.

Add a check for the kmap_local_page() address range to is_kmap_addr().

Cc: Matthew Wilcox <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 include/linux/highmem-internal.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h
index 034b1106d022..5fd5cb58f109 100644
--- a/include/linux/highmem-internal.h
+++ b/include/linux/highmem-internal.h
@@ -152,7 +152,10 @@ static inline void totalhigh_pages_add(long count)
 static inline bool is_kmap_addr(const void *x)
 {
 	unsigned long addr = (unsigned long)x;
-	return addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP);
+
+	return (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) ||
+		(addr >= __fix_to_virt(FIX_KMAP_END) &&
+		 addr < __fix_to_virt(FIX_KMAP_BEGIN));
 }
 #else /* CONFIG_HIGHMEM */
 
-- 
2.37.2

[PATCH 2/4] tee: Remove vmalloc page support

[ira.weiny]

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From: Ira Weiny <ira.weiny@intel.com>

The kernel pages used by shm_get_kernel_pages() are allocated using
GFP_KERNEL through the following call stack:

trusted_instantiate()
	trusted_payload_alloc() -> GFP_KERNEL
	<trusted key op>
		tee_shm_register_kernel_buf()
			register_shm_helper()
				shm_get_kernel_pages()

Where <trusted key op> is one of:

	trusted_key_unseal()
	trusted_key_get_random()
	trusted_key_seal()

Remove the vmalloc page support from shm_get_kernel_pages().  Replace
with a warn on once.

Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Jens I went with the suggestion from Linus and Christoph and rejected
vmalloc addresses.  I did not hear back from you regarding Linus'
question if the vmalloc page support was required by an up coming patch
set or not.  So I assumed it was something out of tree.
---
 drivers/tee/tee_shm.c | 36 ++++++++++++------------------------
 1 file changed, 12 insertions(+), 24 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 27295bda3e0b..527a6eabc03e 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -24,37 +24,25 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count)
 static int shm_get_kernel_pages(unsigned long start, size_t page_count,
 				struct page **pages)
 {
+	struct kvec *kiov;
 	size_t n;
 	int rc;
 
-	if (is_vmalloc_addr((void *)start)) {
-		struct page *page;
-
-		for (n = 0; n < page_count; n++) {
-			page = vmalloc_to_page((void *)(start + PAGE_SIZE * n));
-			if (!page)
-				return -ENOMEM;
-
-			get_page(page);
-			pages[n] = page;
-		}
-		rc = page_count;
-	} else {
-		struct kvec *kiov;
-
-		kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
-		if (!kiov)
-			return -ENOMEM;
+	if (WARN_ON_ONCE(is_vmalloc_addr((void *)start)))
+		return -EINVAL;
 
-		for (n = 0; n < page_count; n++) {
-			kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
-			kiov[n].iov_len = PAGE_SIZE;
-		}
+	kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
+	if (!kiov)
+		return -ENOMEM;
 
-		rc = get_kernel_pages(kiov, page_count, 0, pages);
-		kfree(kiov);
+	for (n = 0; n < page_count; n++) {
+		kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
+		kiov[n].iov_len = PAGE_SIZE;
 	}
 
+	rc = get_kernel_pages(kiov, page_count, 0, pages);
+	kfree(kiov);
+
 	return rc;
 }
 
-- 
2.37.2

Re: [PATCH 2/4] tee: Remove vmalloc page support

[Jens Wiklander]

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Hi Ira,

On Sun, Oct 2, 2022 at 2:23 AM <ira.weiny@intel.com> wrote:
>
> From: Ira Weiny <ira.weiny@intel.com>
>
> The kernel pages used by shm_get_kernel_pages() are allocated using
> GFP_KERNEL through the following call stack:
>
> trusted_instantiate()
>         trusted_payload_alloc() -> GFP_KERNEL
>         <trusted key op>
>                 tee_shm_register_kernel_buf()
>                         register_shm_helper()
>                                 shm_get_kernel_pages()
>
> Where <trusted key op> is one of:
>
>         trusted_key_unseal()
>         trusted_key_get_random()
>         trusted_key_seal()
>
> Remove the vmalloc page support from shm_get_kernel_pages().  Replace
> with a warn on once.
>
> Cc: Jens Wiklander <jens.wiklander@linaro.org>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
>
> ---
> Jens I went with the suggestion from Linus and Christoph and rejected
> vmalloc addresses.  I did not hear back from you regarding Linus'
> question if the vmalloc page support was required by an up coming patch
> set or not.  So I assumed it was something out of tree.

Yes, that's correctly assumed, sorry for not confirming that earlier.

Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>

Thanks,
Jens

> ---
>  drivers/tee/tee_shm.c | 36 ++++++++++++------------------------
>  1 file changed, 12 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 27295bda3e0b..527a6eabc03e 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -24,37 +24,25 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count)
>  static int shm_get_kernel_pages(unsigned long start, size_t page_count,
>                                 struct page **pages)
>  {
> +       struct kvec *kiov;
>         size_t n;
>         int rc;
>
> -       if (is_vmalloc_addr((void *)start)) {
> -               struct page *page;
> -
> -               for (n = 0; n < page_count; n++) {
> -                       page = vmalloc_to_page((void *)(start + PAGE_SIZE * n));
> -                       if (!page)
> -                               return -ENOMEM;
> -
> -                       get_page(page);
> -                       pages[n] = page;
> -               }
> -               rc = page_count;
> -       } else {
> -               struct kvec *kiov;
> -
> -               kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> -               if (!kiov)
> -                       return -ENOMEM;
> +       if (WARN_ON_ONCE(is_vmalloc_addr((void *)start)))
> +               return -EINVAL;
>
> -               for (n = 0; n < page_count; n++) {
> -                       kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> -                       kiov[n].iov_len = PAGE_SIZE;
> -               }
> +       kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> +       if (!kiov)
> +               return -ENOMEM;
>
> -               rc = get_kernel_pages(kiov, page_count, 0, pages);
> -               kfree(kiov);
> +       for (n = 0; n < page_count; n++) {
> +               kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> +               kiov[n].iov_len = PAGE_SIZE;
>         }
>
> +       rc = get_kernel_pages(kiov, page_count, 0, pages);
> +       kfree(kiov);
> +
>         return rc;
>  }
>
> --
> 2.37.2
>

Re: [PATCH 2/4] tee: Remove vmalloc page support

[Sumit Garg]

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+ Phil

Hi Ira,

On Sun, 2 Oct 2022 at 05:53, <ira.weiny@intel.com> wrote:
>
> From: Ira Weiny <ira.weiny@intel.com>
>
> The kernel pages used by shm_get_kernel_pages() are allocated using
> GFP_KERNEL through the following call stack:
>
> trusted_instantiate()
>         trusted_payload_alloc() -> GFP_KERNEL
>         <trusted key op>
>                 tee_shm_register_kernel_buf()
>                         register_shm_helper()
>                                 shm_get_kernel_pages()
>
> Where <trusted key op> is one of:
>
>         trusted_key_unseal()
>         trusted_key_get_random()
>         trusted_key_seal()
>
> Remove the vmalloc page support from shm_get_kernel_pages().  Replace
> with a warn on once.
>
> Cc: Jens Wiklander <jens.wiklander@linaro.org>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
>
> ---
> Jens I went with the suggestion from Linus and Christoph and rejected
> vmalloc addresses.  I did not hear back from you regarding Linus'
> question if the vmalloc page support was required by an up coming patch
> set or not.  So I assumed it was something out of tree.

It looks like I wasn't CC'd to that conversation. IIRC, support for
vmalloc addresses was added recently by Phil here [1]. So I would like
to give him a chance if he is planning to post a corresponding kernel
driver upstream.

[1] https://lists.trustedfirmware.org/archives/list/op-tee(a)lists.trustedfirmware.org/thread/M7HI3P2M66V27SK35CGQRICZ7DJZ5J2W/

-Sumit

> ---
>  drivers/tee/tee_shm.c | 36 ++++++++++++------------------------
>  1 file changed, 12 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 27295bda3e0b..527a6eabc03e 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -24,37 +24,25 @@ static void shm_put_kernel_pages(struct page **pages, size_t page_count)
>  static int shm_get_kernel_pages(unsigned long start, size_t page_count,
>                                 struct page **pages)
>  {
> +       struct kvec *kiov;
>         size_t n;
>         int rc;
>
> -       if (is_vmalloc_addr((void *)start)) {
> -               struct page *page;
> -
> -               for (n = 0; n < page_count; n++) {
> -                       page = vmalloc_to_page((void *)(start + PAGE_SIZE * n));
> -                       if (!page)
> -                               return -ENOMEM;
> -
> -                       get_page(page);
> -                       pages[n] = page;
> -               }
> -               rc = page_count;
> -       } else {
> -               struct kvec *kiov;
> -
> -               kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> -               if (!kiov)
> -                       return -ENOMEM;
> +       if (WARN_ON_ONCE(is_vmalloc_addr((void *)start)))
> +               return -EINVAL;
>
> -               for (n = 0; n < page_count; n++) {
> -                       kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> -                       kiov[n].iov_len = PAGE_SIZE;
> -               }
> +       kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> +       if (!kiov)
> +               return -ENOMEM;
>
> -               rc = get_kernel_pages(kiov, page_count, 0, pages);
> -               kfree(kiov);
> +       for (n = 0; n < page_count; n++) {
> +               kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> +               kiov[n].iov_len = PAGE_SIZE;
>         }
>
> +       rc = get_kernel_pages(kiov, page_count, 0, pages);
> +       kfree(kiov);
> +
>         return rc;
>  }
>
> --
> 2.37.2
>

[PATCH 3/4] tee: Remove call to get_kernel_pages()

[ira.weiny]

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From: Ira Weiny <ira.weiny@intel.com>

The kernel pages used by shm_get_kernel_pages() are allocated using
GFP_KERNEL through the following call stack:

trusted_instantiate()
	trusted_payload_alloc() -> GFP_KERNEL
	<trusted key op>
		tee_shm_register_kernel_buf()
			register_shm_helper()
				shm_get_kernel_pages()

Where <trusted key op> is one of:

	trusted_key_unseal()
	trusted_key_get_random()
	trusted_key_seal()

Because the pages can't be from highmem get_kernel_pages() boils down to
a get_page() call.

Remove the get_kernel_pages() call and open code the get_page().

In case a kmap page does slip through warn on once for a kmap address.

Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 drivers/tee/tee_shm.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 527a6eabc03e..45e6ff1a452e 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -11,6 +11,7 @@
 #include <linux/tee_drv.h>
 #include <linux/uaccess.h>
 #include <linux/uio.h>
+#include <linux/highmem.h>
 #include "tee_private.h"
 
 static void shm_put_kernel_pages(struct page **pages, size_t page_count)
@@ -26,9 +27,9 @@ static int shm_get_kernel_pages(unsigned long start, size_t page_count,
 {
 	struct kvec *kiov;
 	size_t n;
-	int rc;
 
-	if (WARN_ON_ONCE(is_vmalloc_addr((void *)start)))
+	if (WARN_ON_ONCE(is_vmalloc_addr((void *)start) ||
+			 is_kmap_addr((void *)start)))
 		return -EINVAL;
 
 	kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
@@ -38,12 +39,12 @@ static int shm_get_kernel_pages(unsigned long start, size_t page_count,
 	for (n = 0; n < page_count; n++) {
 		kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
 		kiov[n].iov_len = PAGE_SIZE;
+		pages[n] = virt_to_page(kiov[n].iov_base);
+		get_page(pages[n]);
 	}
-
-	rc = get_kernel_pages(kiov, page_count, 0, pages);
 	kfree(kiov);
 
-	return rc;
+	return page_count;
 }
 
 static void release_registered_pages(struct tee_shm *shm)
-- 
2.37.2

Re: [PATCH 3/4] tee: Remove call to get_kernel_pages()

[Al Viro]

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On Sat, Oct 01, 2022 at 05:23:25PM -0700, ira.weiny(a)intel.com wrote:

>  	kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> @@ -38,12 +39,12 @@ static int shm_get_kernel_pages(unsigned long start, size_t page_count,
>  	for (n = 0; n < page_count; n++) {
>  		kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
>  		kiov[n].iov_len = PAGE_SIZE;
> +		pages[n] = virt_to_page(kiov[n].iov_base);
> +		get_page(pages[n]);
>  	}
> -
> -	rc = get_kernel_pages(kiov, page_count, 0, pages);
>  	kfree(kiov);

IDGI.  The only thing in kiov[...] you are every reading is
->iov_base.  And you fetch it once, right after the assignment.

Why bother with allocating the array at all?
		pages[n] = virt_to_page((void *)start + n * PAGE_SIZE);
would do just as well, not to mention the fact that since you reject
vmalloc and kmap, you might simply do

	page = virt_to_page(start);
	for (int n = 0; n < page_count; n++)
		get_page(pages[n] = page + n);

instead...

Re: [PATCH 3/4] tee: Remove call to get_kernel_pages()

[Ira Weiny]

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On Sun, Oct 02, 2022 at 01:46:41AM +0100, Al Viro wrote:
> On Sat, Oct 01, 2022 at 05:23:25PM -0700, ira.weiny(a)intel.com wrote:
> 
> >  	kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> > @@ -38,12 +39,12 @@ static int shm_get_kernel_pages(unsigned long start, size_t page_count,
> >  	for (n = 0; n < page_count; n++) {
> >  		kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> >  		kiov[n].iov_len = PAGE_SIZE;
> > +		pages[n] = virt_to_page(kiov[n].iov_base);
> > +		get_page(pages[n]);
> >  	}
> > -
> > -	rc = get_kernel_pages(kiov, page_count, 0, pages);
> >  	kfree(kiov);
> 
> IDGI.  The only thing in kiov[...] you are every reading is
> ->iov_base.  And you fetch it once, right after the assignment.

:-(  Good point.  Thanks for catching that.  I was too focused on just
replacing get_kernel_pages() with get_page() and I should have refactored
more.

> 
> Why bother with allocating the array at all?
> 		pages[n] = virt_to_page((void *)start + n * PAGE_SIZE);
> would do just as well, not to mention the fact that since you reject
> vmalloc and kmap, you might simply do
> 
> 	page = virt_to_page(start);
> 	for (int n = 0; n < page_count; n++)
> 		get_page(pages[n] = page + n);

I think I'd avoid the assignment in the parameter as I would miss that if I
came back and looked at this code later.

I'll get rid of the kiov in v2.

Sorry for not cleaning it up more and thanks for the review!

Ira

Re: [PATCH 3/4] tee: Remove call to get_kernel_pages()

[Christoph Hellwig]

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On Sun, Oct 02, 2022 at 01:46:41AM +0100, Al Viro wrote:
> IDGI.  The only thing in kiov[...] you are every reading is
> ->iov_base.  And you fetch it once, right after the assignment.

... and that's exactly what I pointed out on the last version of the
patch ...

Re: [PATCH 3/4] tee: Remove call to get_kernel_pages()

[Ira Weiny]

[-- Attachment #1: Type: text/plain, Size: 381 bytes --]

On Mon, Oct 03, 2022 at 09:17:18AM +0200, Christoph Hellwig wrote:
> On Sun, Oct 02, 2022 at 01:46:41AM +0100, Al Viro wrote:
> > IDGI.  The only thing in kiov[...] you are every reading is
> > ->iov_base.  And you fetch it once, right after the assignment.
> 
> ... and that's exactly what I pointed out on the last version of the
> patch ...

Apologies I guess I missed it.
Ira

[PATCH 4/4] mm: Remove get_kernel_pages()

[ira.weiny]

[-- Attachment #1: Type: text/plain, Size: 2394 bytes --]

From: Ira Weiny <ira.weiny@intel.com>

The only caller to get_kernel_pages() [shm_get_kernel_pages()] has been
updated to not need it.

Remove get_kernel_pages().

Cc: Mel Gorman <mgorman@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 include/linux/mm.h |  2 --
 mm/swap.c          | 30 ------------------------------
 2 files changed, 32 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8bbcccbc5565..9a06df4f057c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1969,8 +1969,6 @@ int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
 			struct task_struct *task, bool bypass_rlim);
 
 struct kvec;
-int get_kernel_pages(const struct kvec *iov, int nr_pages, int write,
-			struct page **pages);
 struct page *get_dump_page(unsigned long addr);
 
 bool folio_mark_dirty(struct folio *folio);
diff --git a/mm/swap.c b/mm/swap.c
index 955930f41d20..a9aa648eb0d0 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -157,36 +157,6 @@ void put_pages_list(struct list_head *pages)
 }
 EXPORT_SYMBOL(put_pages_list);
 
-/*
- * get_kernel_pages() - pin kernel pages in memory
- * @kiov:	An array of struct kvec structures
- * @nr_segs:	number of segments to pin
- * @write:	pinning for read/write, currently ignored
- * @pages:	array that receives pointers to the pages pinned.
- *		Should be at least nr_segs long.
- *
- * Returns number of pages pinned. This may be fewer than the number requested.
- * If nr_segs is 0 or negative, returns 0.  If no pages were pinned, returns 0.
- * Each page returned must be released with a put_page() call when it is
- * finished with.
- */
-int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
-		struct page **pages)
-{
-	int seg;
-
-	for (seg = 0; seg < nr_segs; seg++) {
-		if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
-			return seg;
-
-		pages[seg] = kmap_to_page(kiov[seg].iov_base);
-		get_page(pages[seg]);
-	}
-
-	return seg;
-}
-EXPORT_SYMBOL_GPL(get_kernel_pages);
-
 typedef void (*move_fn_t)(struct lruvec *lruvec, struct folio *folio);
 
 static void lru_add_fn(struct lruvec *lruvec, struct folio *folio)
-- 
2.37.2

Re: [PATCH 4/4] mm: Remove get_kernel_pages()

[John Hubbard]

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On 10/1/22 17:23, ira.weiny(a)intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> The only caller to get_kernel_pages() [shm_get_kernel_pages()] has been
> updated to not need it.
> 
> Remove get_kernel_pages().
> 
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
>   include/linux/mm.h |  2 --
>   mm/swap.c          | 30 ------------------------------
>   2 files changed, 32 deletions(-)
> 

Good to see this removed (including the EXPORT), even if the
functionality still remains in a less obvious form, over in shm.

The fewer "all your page are pinned" calls we need, the simpler things
get. :)


Acked-by: John Hubbard <jhubbard@nvidia.com>

thanks,
-- 
John Hubbard
NVIDIA

> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 8bbcccbc5565..9a06df4f057c 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1969,8 +1969,6 @@ int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
>   			struct task_struct *task, bool bypass_rlim);
>   
>   struct kvec;
> -int get_kernel_pages(const struct kvec *iov, int nr_pages, int write,
> -			struct page **pages);
>   struct page *get_dump_page(unsigned long addr);
>   
>   bool folio_mark_dirty(struct folio *folio);
> diff --git a/mm/swap.c b/mm/swap.c
> index 955930f41d20..a9aa648eb0d0 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -157,36 +157,6 @@ void put_pages_list(struct list_head *pages)
>   }
>   EXPORT_SYMBOL(put_pages_list);
>   
> -/*
> - * get_kernel_pages() - pin kernel pages in memory
> - * @kiov:	An array of struct kvec structures
> - * @nr_segs:	number of segments to pin
> - * @write:	pinning for read/write, currently ignored
> - * @pages:	array that receives pointers to the pages pinned.
> - *		Should be at least nr_segs long.
> - *
> - * Returns number of pages pinned. This may be fewer than the number requested.
> - * If nr_segs is 0 or negative, returns 0.  If no pages were pinned, returns 0.
> - * Each page returned must be released with a put_page() call when it is
> - * finished with.
> - */
> -int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
> -		struct page **pages)
> -{
> -	int seg;
> -
> -	for (seg = 0; seg < nr_segs; seg++) {
> -		if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
> -			return seg;
> -
> -		pages[seg] = kmap_to_page(kiov[seg].iov_base);
> -		get_page(pages[seg]);
> -	}
> -
> -	return seg;
> -}
> -EXPORT_SYMBOL_GPL(get_kernel_pages);
> -
>   typedef void (*move_fn_t)(struct lruvec *lruvec, struct folio *folio);
>   
>   static void lru_add_fn(struct lruvec *lruvec, struct folio *folio)

Re: [PATCH 0/4] Remove get_kernel_pages()

[Sumit Garg]

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Hi Ira,

On Sun, 2 Oct 2022 at 05:53, <ira.weiny@intel.com> wrote:
>
> From: Ira Weiny <ira.weiny@intel.com>
>
> get_kernel_pages() only had one caller [shm_get_kernel_pages()] which did not
> need the functionality it provided.  Furthermore, it called kmap_to_page()
> which we are looking to removed.
>
> Alter shm_get_kernel_pages() to no longer call get_kernel_pages() and remove
> get_kernel_pages().  Along the way it was noted that shm_get_kernel_pages()
> does not have any need to support vmalloc'ed addresses either.  Remove that
> functionality to clean up the logic.
>
> This series also fixes and uses is_kmap_addr().

From the above description, I am failing to see the motivation behind
this change. Can you elaborate here?

Also, since you are targeting to remove kmap_to_page(), is there any
alternative way to support highmem for future TEE bus drivers? As I
can see higmem being enabled for multiple Arm defconfigs [1] which can
also support TEE (an example which already does it:
arch/arm/configs/imx_v6_v7_defconfig).

[1] git grep CONFIG_HIGHMEM arch/arm/

-Sumit

>
> Ira Weiny (4):
>   highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings
>   tee: Remove vmalloc page support
>   tee: Remove call to get_kernel_pages()
>   mm: Remove get_kernel_pages()
>
>  drivers/tee/tee_shm.c            | 41 ++++++++++++--------------------
>  include/linux/highmem-internal.h |  5 +++-
>  include/linux/mm.h               |  2 --
>  mm/swap.c                        | 30 -----------------------
>  4 files changed, 19 insertions(+), 59 deletions(-)
>
>
> base-commit: 274d7803837da78dfc911bcda0d593412676fc20
> --
> 2.37.2
>