[PATCH v2 0/4] Remove get_kernel_pages()

[PATCH v2 0/4] Remove get_kernel_pages()

[Ira Weiny]

Sumit,

I did not see a follow up on this series per your last email.[1]  I'd like to
move forward with getting rid of kmap_to_page().  So Hopefully this can land
and you can build on this rather than the other way around?

All,

Al Viro found[2] that kmap_to_page() is broken.  But not only is it broken, it
presents confusion over how highmem should be used because kmap() and friends
should not be used for 'long term' mappings.

get_kernel_pages() is a caller of kmap_to_page().  It only has one caller
[shm_get_kernel_pages()] which does not need the functionality.

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 is_kmap_addr() and uses it to ensure no kmap addresses
slip in later.

[1] https://lore.kernel.org/all/CAFA6WYMqEVDVW-ifoh-V9ni1zntYdes8adQKf2XXAUpqdaW53w@mail.gmail.com/
[2] https://lore.kernel.org/lkml/YzSSl1ItVlARDvG3@ZenIV

To: Sumit Garg <sumit.garg@linaro.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Al Viro" <viro@zeniv.linux.org.uk>
Cc: "Christoph Hellwig" <hch@lst.de>
Cc: linux-kernel@vger.kernel.org
Cc: op-tee@lists.trustedfirmware.org
Cc: linux-mm@kvack.org
Cc: Jens Wiklander <jens.wiklander@linaro.org>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes in v2:
- Al Viro: Avoid allocating the kiov.
- Sumit: Update cover letter to clarify the motivation behind removing
  get_kernel_pages()
- Link to v1: https://lore.kernel.org/r/20221002002326.946620-1-ira.weiny@intel.com

---
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            | 37 ++++++++++---------------------------
 include/linux/highmem-internal.h |  5 ++++-
 include/linux/mm.h               |  2 --
 mm/swap.c                        | 30 ------------------------------
 4 files changed, 14 insertions(+), 60 deletions(-)
---
base-commit: 0136d86b78522bbd5755f8194c97a987f0586ba5
change-id: 20230203-get_kernel_pages-199342cfba79

Best regards,
-- 
Ira Weiny <ira.weiny@intel.com>

[PATCH v2 1/4] highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings

[Ira Weiny]

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 e098f38422af..a3028e400a9c 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 */
 

-- 
2.39.1

[PATCH v2 2/4] tee: Remove vmalloc page support

[Ira Weiny]

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: 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>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
 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;
 }
 

-- 
2.39.1

[PATCH v2 3/4] tee: Remove call to get_kernel_pages()

[Ira Weiny]

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 highmem page does slip through warn on once for a kmap'ed
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>

---
Changes from v1:
	Al/Christoph: Remove kiov altogether
---
 drivers/tee/tee_shm.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 527a6eabc03e..b1c6231defad 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)
@@ -24,26 +25,20 @@ 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;
+	struct page *page;
 	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);
-	if (!kiov)
-		return -ENOMEM;
-
+	page = virt_to_page(start);
 	for (n = 0; n < page_count; n++) {
-		kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
-		kiov[n].iov_len = PAGE_SIZE;
+		pages[n] = page + n;
+		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)

-- 
2.39.1

[PATCH v2 4/4] mm: Remove get_kernel_pages()

[Ira Weiny]

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>
Acked-by: John Hubbard <jhubbard@nvidia.com>
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 8f857163ac89..2041e6d4fa27 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2095,8 +2095,6 @@ 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 70e2063ef43a..4c03ecab698e 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -158,36 +158,6 @@ 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)

-- 
2.39.1

Re: [PATCH v2 1/4] highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings

[Christoph Hellwig]

On Fri, Feb 03, 2023 at 08:06:32PM -0800, Ira Weiny wrote:
> -	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));

Isn't the second check inverted?

Re: [PATCH v2 2/4] tee: Remove vmalloc page support

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v2 3/4] tee: Remove call to get_kernel_pages()

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v2 4/4] mm: Remove get_kernel_pages()

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v2 1/4] highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings

[Ira Weiny]

Christoph Hellwig wrote:
> On Fri, Feb 03, 2023 at 08:06:32PM -0800, Ira Weiny wrote:
> > -	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));
> 
> Isn't the second check inverted?
> 

The enum map runs from top down.  So I believe this is correct.  I tested
it with a different series and it worked.

Ira

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Linus Torvalds]

On Fri, Feb 3, 2023 at 8:06 PM Ira Weiny <ira.weiny@intel.com> wrote:
>
> This series also fixes is_kmap_addr() and uses it to ensure no kmap addresses
> slip in later.

Ack. Please make it so.

That said...

I wasn't cc'd on all the patches, but checked them on the mailing
list, and that first is_kmap_addr() patch makes me a bit unhappy.

Right now that 'is_kmap_addr()' is only used for user copy addresses,
for debugging purposes, and I'm not exactly thrilled about extending
it this way.

I get the feeling that we should just have a name for that "kmap _or_
kmap_local" range instead of making it two ranges.

But admittedly I can't come up with anything better, and it looks like
different architectures may do different things.  I just don't like
it.

                Linus

Re: [PATCH v2 2/4] tee: Remove vmalloc page support

[Sumit Garg]

On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
>
> 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: 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>
> Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
>  drivers/tee/tee_shm.c | 36 ++++++++++++------------------------
>  1 file changed, 12 insertions(+), 24 deletions(-)
>

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>

-Sumit

> 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;
>  }
>
>
> --
> 2.39.1

Re: [PATCH v2 3/4] tee: Remove call to get_kernel_pages()

[Sumit Garg]

On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
>
> 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 highmem page does slip through warn on once for a kmap'ed
> 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>
>
> ---
> Changes from v1:
>         Al/Christoph: Remove kiov altogether
> ---
>  drivers/tee/tee_shm.c | 21 ++++++++-------------
>  1 file changed, 8 insertions(+), 13 deletions(-)
>

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>

-Sumit

> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 527a6eabc03e..b1c6231defad 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)
> @@ -24,26 +25,20 @@ 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;
> +       struct page *page;
>         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);
> -       if (!kiov)
> -               return -ENOMEM;
> -
> +       page = virt_to_page(start);
>         for (n = 0; n < page_count; n++) {
> -               kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> -               kiov[n].iov_len = PAGE_SIZE;
> +               pages[n] = page + n;
> +               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)
>
> --
> 2.39.1

Re: [PATCH v2 4/4] mm: Remove get_kernel_pages()

[Sumit Garg]

On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
>
> 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>
> Acked-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
>  include/linux/mm.h |  2 --
>  mm/swap.c          | 30 ------------------------------
>  2 files changed, 32 deletions(-)
>

Reviewed-by: Sumit Garg <sumit.garg@linaro.org>

-Sumit

> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 8f857163ac89..2041e6d4fa27 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2095,8 +2095,6 @@ 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 70e2063ef43a..4c03ecab698e 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -158,36 +158,6 @@ 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)
>
> --
> 2.39.1

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Sumit Garg]

On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
>
> Sumit,
>
> I did not see a follow up on this series per your last email.[1]  I'd like to
> move forward with getting rid of kmap_to_page().  So Hopefully this can land
> and you can build on this rather than the other way around?

Apologies Ira for keeping you waiting. Actually I was fully involved
with other high priority work with my upstream review backlog
increasing. So I wasn't able to devote time to this work. Sure I will
rebase my work on top of your changes.

-Sumit

>
> All,
>
> Al Viro found[2] that kmap_to_page() is broken.  But not only is it broken, it
> presents confusion over how highmem should be used because kmap() and friends
> should not be used for 'long term' mappings.
>
> get_kernel_pages() is a caller of kmap_to_page().  It only has one caller
> [shm_get_kernel_pages()] which does not need the functionality.
>
> 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 is_kmap_addr() and uses it to ensure no kmap addresses
> slip in later.
>
> [1] https://lore.kernel.org/all/CAFA6WYMqEVDVW-ifoh-V9ni1zntYdes8adQKf2XXAUpqdaW53w@mail.gmail.com/
> [2] https://lore.kernel.org/lkml/YzSSl1ItVlARDvG3@ZenIV
>
> To: Sumit Garg <sumit.garg@linaro.org>
> To: Andrew Morton <akpm@linux-foundation.org>
> Cc: "Al Viro" <viro@zeniv.linux.org.uk>
> Cc: "Christoph Hellwig" <hch@lst.de>
> Cc: linux-kernel@vger.kernel.org
> Cc: op-tee@lists.trustedfirmware.org
> Cc: linux-mm@kvack.org
> Cc: Jens Wiklander <jens.wiklander@linaro.org>
> Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
>
> ---
> Changes in v2:
> - Al Viro: Avoid allocating the kiov.
> - Sumit: Update cover letter to clarify the motivation behind removing
>   get_kernel_pages()
> - Link to v1: https://lore.kernel.org/r/20221002002326.946620-1-ira.weiny@intel.com
>
> ---
> 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            | 37 ++++++++++---------------------------
>  include/linux/highmem-internal.h |  5 ++++-
>  include/linux/mm.h               |  2 --
>  mm/swap.c                        | 30 ------------------------------
>  4 files changed, 14 insertions(+), 60 deletions(-)
> ---
> base-commit: 0136d86b78522bbd5755f8194c97a987f0586ba5
> change-id: 20230203-get_kernel_pages-199342cfba79
>
> Best regards,
> --
> Ira Weiny <ira.weiny@intel.com>

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Ira Weiny]

Sumit Garg wrote:
> On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
> >
> > Sumit,
> >
> > I did not see a follow up on this series per your last email.[1]  I'd like to
> > move forward with getting rid of kmap_to_page().  So Hopefully this can land
> > and you can build on this rather than the other way around?
> 
> Apologies Ira for keeping you waiting. Actually I was fully involved
> with other high priority work with my upstream review backlog
> increasing. So I wasn't able to devote time to this work. Sure I will
> rebase my work on top of your changes.

No problem on my end.  I just wanted to ensure that I did not miss
something.

Thanks for the reviews!
Ira

> 
> -Sumit
> 
> >
> > All,
> >
> > Al Viro found[2] that kmap_to_page() is broken.  But not only is it broken, it
> > presents confusion over how highmem should be used because kmap() and friends
> > should not be used for 'long term' mappings.
> >
> > get_kernel_pages() is a caller of kmap_to_page().  It only has one caller
> > [shm_get_kernel_pages()] which does not need the functionality.
> >
> > 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 is_kmap_addr() and uses it to ensure no kmap addresses
> > slip in later.
> >
> > [1] https://lore.kernel.org/all/CAFA6WYMqEVDVW-ifoh-V9ni1zntYdes8adQKf2XXAUpqdaW53w@mail.gmail.com/
> > [2] https://lore.kernel.org/lkml/YzSSl1ItVlARDvG3@ZenIV
> >
> > To: Sumit Garg <sumit.garg@linaro.org>
> > To: Andrew Morton <akpm@linux-foundation.org>
> > Cc: "Al Viro" <viro@zeniv.linux.org.uk>
> > Cc: "Christoph Hellwig" <hch@lst.de>
> > Cc: linux-kernel@vger.kernel.org
> > Cc: op-tee@lists.trustedfirmware.org
> > Cc: linux-mm@kvack.org
> > Cc: Jens Wiklander <jens.wiklander@linaro.org>
> > Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> >
> > ---
> > Changes in v2:
> > - Al Viro: Avoid allocating the kiov.
> > - Sumit: Update cover letter to clarify the motivation behind removing
> >   get_kernel_pages()
> > - Link to v1: https://lore.kernel.org/r/20221002002326.946620-1-ira.weiny@intel.com
> >
> > ---
> > 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            | 37 ++++++++++---------------------------
> >  include/linux/highmem-internal.h |  5 ++++-
> >  include/linux/mm.h               |  2 --
> >  mm/swap.c                        | 30 ------------------------------
> >  4 files changed, 14 insertions(+), 60 deletions(-)
> > ---
> > base-commit: 0136d86b78522bbd5755f8194c97a987f0586ba5
> > change-id: 20230203-get_kernel_pages-199342cfba79
> >
> > Best regards,
> > --
> > Ira Weiny <ira.weiny@intel.com>

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Ira Weiny]

Ira Weiny wrote:
> Sumit Garg wrote:
> > On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
> > >
> > > Sumit,
> > >
> > > I did not see a follow up on this series per your last email.[1]  I'd like to
> > > move forward with getting rid of kmap_to_page().  So Hopefully this can land
> > > and you can build on this rather than the other way around?
> > 
> > Apologies Ira for keeping you waiting. Actually I was fully involved
> > with other high priority work with my upstream review backlog
> > increasing. So I wasn't able to devote time to this work. Sure I will
> > rebase my work on top of your changes.
> 
> No problem on my end.  I just wanted to ensure that I did not miss
> something.

Andrew, can I get an ack on patches 1 and 4 for this series?  I realized
that perhaps I was not clear on my expectations of this series.  I was
thinking this would be easiest to go through the tee subsystem tree.

Sumit or Jens, is that ok with you all?

Thanks,
Ira

Re: [PATCH v2 1/4] highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings

[Andrew Morton]

On Fri, 03 Feb 2023 20:06:32 -0800 Ira Weiny <ira.weiny@intel.com> wrote:

> 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().

Acked-by: Andrew Morton <akpm@linux-foudation.org>

Re: [PATCH v2 4/4] mm: Remove get_kernel_pages()

[Andrew Morton]

On Fri, 03 Feb 2023 20:06:35 -0800 Ira Weiny <ira.weiny@intel.com> wrote:

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

Acked-by: Andrew Morton <akpm@linux-foudation.org>

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Jens Wiklander]

Hi Ira,

On Fri, Feb 10, 2023 at 9:28 PM Ira Weiny <ira.weiny@intel.com> wrote:
>
> Ira Weiny wrote:
> > Sumit Garg wrote:
> > > On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
> > > >
> > > > Sumit,
> > > >
> > > > I did not see a follow up on this series per your last email.[1]  I'd like to
> > > > move forward with getting rid of kmap_to_page().  So Hopefully this can land
> > > > and you can build on this rather than the other way around?
> > >
> > > Apologies Ira for keeping you waiting. Actually I was fully involved
> > > with other high priority work with my upstream review backlog
> > > increasing. So I wasn't able to devote time to this work. Sure I will
> > > rebase my work on top of your changes.
> >
> > No problem on my end.  I just wanted to ensure that I did not miss
> > something.
>
> Andrew, can I get an ack on patches 1 and 4 for this series?  I realized
> that perhaps I was not clear on my expectations of this series.  I was
> thinking this would be easiest to go through the tee subsystem tree.
>
> Sumit or Jens, is that ok with you all?

Sure, I'll take it. The timing is a bit unfortunate, it's likely too
close to the merge window to be included there. However, I'll pick it
up and add it to linux-next so it's ready for the 6.4 merge window.

Thanks,
Jens

Re: [PATCH v2 1/4] highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings

[Jens Wiklander]

On Fri, Feb 03, 2023 at 08:06:32PM -0800, Ira Weiny wrote:
> 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(-)
> 

Added to https://git.linaro.org/people/jens.wiklander/linux-tee.git/log/?h=get_kernel_pages-for-v6.4

Thanks,
Jens

> diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h
> index e098f38422af..a3028e400a9c 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 */
>  
> 
> -- 
> 2.39.1

Re: [PATCH v2 2/4] tee: Remove vmalloc page support

[Jens Wiklander]

On Fri, Feb 03, 2023 at 08:06:33PM -0800, Ira Weiny wrote:
> 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: 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>
> Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
>  drivers/tee/tee_shm.c | 36 ++++++++++++------------------------
>  1 file changed, 12 insertions(+), 24 deletions(-)

Added to https://git.linaro.org/people/jens.wiklander/linux-tee.git/log/?h=get_kernel_pages-for-v6.4

Thanks,
Jens

> 
> 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;
>  }
>  
> 
> -- 
> 2.39.1

Re: [PATCH v2 3/4] tee: Remove call to get_kernel_pages()

[Jens Wiklander]

On Fri, Feb 03, 2023 at 08:06:34PM -0800, Ira Weiny wrote:
> 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 highmem page does slip through warn on once for a kmap'ed
> 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>
> 
> ---
> Changes from v1:
> 	Al/Christoph: Remove kiov altogether
> ---
>  drivers/tee/tee_shm.c | 21 ++++++++-------------
>  1 file changed, 8 insertions(+), 13 deletions(-)

Added to https://git.linaro.org/people/jens.wiklander/linux-tee.git/log/?h=get_kernel_pages-for-v6.4

Thanks,
Jens

> 
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 527a6eabc03e..b1c6231defad 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)
> @@ -24,26 +25,20 @@ 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;
> +	struct page *page;
>  	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);
> -	if (!kiov)
> -		return -ENOMEM;
> -
> +	page = virt_to_page(start);
>  	for (n = 0; n < page_count; n++) {
> -		kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> -		kiov[n].iov_len = PAGE_SIZE;
> +		pages[n] = page + n;
> +		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)
> 
> -- 
> 2.39.1

Re: [PATCH v2 4/4] mm: Remove get_kernel_pages()

[Jens Wiklander]

On Fri, Feb 03, 2023 at 08:06:35PM -0800, Ira Weiny wrote:
> 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>
> Acked-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
>  include/linux/mm.h |  2 --
>  mm/swap.c          | 30 ------------------------------
>  2 files changed, 32 deletions(-)

Added to https://git.linaro.org/people/jens.wiklander/linux-tee.git/log/?h=get_kernel_pages-for-v6.4

Thanks,
Jens

> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 8f857163ac89..2041e6d4fa27 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2095,8 +2095,6 @@ 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 70e2063ef43a..4c03ecab698e 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -158,36 +158,6 @@ 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)
> 
> -- 
> 2.39.1

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Ira Weiny]

Jens Wiklander wrote:
> Hi Ira,
> 
> On Fri, Feb 10, 2023 at 9:28 PM Ira Weiny <ira.weiny@intel.com> wrote:
> >
> > Ira Weiny wrote:
> > > Sumit Garg wrote:
> > > > On Sat, 4 Feb 2023 at 09:36, Ira Weiny <ira.weiny@intel.com> wrote:
> > > > >
> > > > > Sumit,
> > > > >
> > > > > I did not see a follow up on this series per your last email.[1]  I'd like to
> > > > > move forward with getting rid of kmap_to_page().  So Hopefully this can land
> > > > > and you can build on this rather than the other way around?
> > > >
> > > > Apologies Ira for keeping you waiting. Actually I was fully involved
> > > > with other high priority work with my upstream review backlog
> > > > increasing. So I wasn't able to devote time to this work. Sure I will
> > > > rebase my work on top of your changes.
> > >
> > > No problem on my end.  I just wanted to ensure that I did not miss
> > > something.
> >
> > Andrew, can I get an ack on patches 1 and 4 for this series?  I realized
> > that perhaps I was not clear on my expectations of this series.  I was
> > thinking this would be easiest to go through the tee subsystem tree.
> >
> > Sumit or Jens, is that ok with you all?
> 
> Sure, I'll take it. The timing is a bit unfortunate, it's likely too
> close to the merge window to be included there. However, I'll pick it
> up and add it to linux-next so it's ready for the 6.4 merge window.

6.4 is fine with me.

Thanks everyone!
Ira

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Linus Torvalds]

On Mon, Feb 13, 2023 at 7:02 AM Jens Wiklander
<jens.wiklander@linaro.org> wrote:
>
> Sure, I'll take it. The timing is a bit unfortunate, it's likely too
> close to the merge window to be included there. However, I'll pick it
> up and add it to linux-next so it's ready for the 6.4 merge window.

With this boeing almost all code removal, I'm perfectly fine taking it
in the upcoming merge window.

           Linus

Re: [PATCH v2 0/4] Remove get_kernel_pages()

[Jens Wiklander]

On Mon, Feb 13, 2023 at 11:02:52AM -0800, Linus Torvalds wrote:
> On Mon, Feb 13, 2023 at 7:02 AM Jens Wiklander
> <jens.wiklander@linaro.org> wrote:
> >
> > Sure, I'll take it. The timing is a bit unfortunate, it's likely too
> > close to the merge window to be included there. However, I'll pick it
> > up and add it to linux-next so it's ready for the 6.4 merge window.
> 
> With this boeing almost all code removal, I'm perfectly fine taking it
> in the upcoming merge window.

OK, thank you.

Cheers,
Jens