+ mm-re-allow-pinning-of-zero-pfns-again.patch added to mm-hotfixes-unstable branch

+ mm-re-allow-pinning-of-zero-pfns-again.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: re-allow pinning of zero pfns (again)
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-re-allow-pinning-of-zero-pfns-again.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-re-allow-pinning-of-zero-pfns-again.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Alex Williamson <alex.williamson@redhat.com>
Subject: mm: re-allow pinning of zero pfns (again)
Date: Mon, 08 Aug 2022 22:42:24 -0600

The below referenced commit makes the same error as 1c563432588d ("mm: fix
is_pinnable_page against a cma page"), re-interpreting the logic to
exclude pinning of the zero page, which breaks device assignment with
vfio.

Link: https://lore.kernel.org/all/165490039431.944052.12458624139225785964.stgit@omen
Link: https://lkml.kernel.org/r/166002010021.381133.11357879752637949308.stgit@omen
Fixes: f25cbb7a95a2 ("mm: add zone device coherent type memory support")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Felix Kuehling <felix.kuehling@amd.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/include/linux/mm.h~mm-re-allow-pinning-of-zero-pfns-again
+++ a/include/linux/mm.h
@@ -1544,9 +1544,8 @@ static inline bool is_longterm_pinnable_
 	if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE)
 		return false;
 #endif
-	return !(is_device_coherent_page(page) ||
-		 is_zone_movable_page(page) ||
-		 is_zero_pfn(page_to_pfn(page)));
+	return !(is_device_coherent_page(page) || is_zone_movable_page(page)) ||
+	       is_zero_pfn(page_to_pfn(page));
 }
 #else
 static inline bool is_longterm_pinnable_page(struct page *page)
_

Patches currently in -mm which might be from alex.williamson@redhat.com are

mm-re-allow-pinning-of-zero-pfns-again.patch

+ mm-re-allow-pinning-of-zero-pfns-again.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: re-allow pinning of zero pfns (again)
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-re-allow-pinning-of-zero-pfns-again.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-re-allow-pinning-of-zero-pfns-again.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Alex Williamson <alex.williamson@redhat.com>
Subject: mm: re-allow pinning of zero pfns (again)
Date: Wed, 10 Aug 2022 10:53:59 -0600

The below referenced commit makes the same error as 1c563432588d ("mm: fix
is_pinnable_page against a cma page"), re-interpreting the logic to
exclude pinning of the zero page, which breaks device assignment with
vfio.

To avoid further subtle mistakes, split the logic into discrete tests.

Link: https://lkml.kernel.org/r/166015037385.760108.16881097713975517242.stgit@omen
Link: https://lore.kernel.org/all/165490039431.944052.12458624139225785964.stgit@omen
Fixes: f25cbb7a95a2 ("mm: add zone device coherent type memory support")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Felix Kuehling <felix.kuehling@amd.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h |   17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

--- a/include/linux/mm.h~mm-re-allow-pinning-of-zero-pfns-again
+++ a/include/linux/mm.h
@@ -1544,9 +1544,20 @@ static inline bool is_longterm_pinnable_
 	if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE)
 		return false;
 #endif
-	return !(is_device_coherent_page(page) ||
-		 is_zone_movable_page(page) ||
-		 is_zero_pfn(page_to_pfn(page)));
+	/*
+	 * The zero page might reside in a movable zone, however it may not
+	 * be migrated and can therefore be pinned.  The vfio subsystem pins
+	 * user mappings including the zero page for IOMMU translation.
+	 */
+	if (is_zero_pfn(page_to_pfn(page)))
+		return true;
+
+	/* Coherent device memory must always allow eviction. */
+	if (is_device_coherent_page(page))
+		return false;
+
+	/* Otherwise, non-movable zone pages can be pinned. */
+	return !is_zone_movable_page(page);
 }
 #else
 static inline bool is_longterm_pinnable_page(struct page *page)
_

Patches currently in -mm which might be from alex.williamson@redhat.com are

mm-re-allow-pinning-of-zero-pfns-again.patch

Re: + mm-re-allow-pinning-of-zero-pfns-again.patch added to mm-hotfixes-unstable branch

[David Hildenbrand]

On 10.08.22 23:44, Andrew Morton wrote:
> 
> The patch titled
>      Subject: mm: re-allow pinning of zero pfns (again)
> has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
>      mm-re-allow-pinning-of-zero-pfns-again.patch
> 
> This patch will shortly appear at
>      https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-re-allow-pinning-of-zero-pfns-again.patch
> 
> This patch will later appear in the mm-hotfixes-unstable branch at
>     git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> 
> Before you just go and hit "reply", please:
>    a) Consider who else should be cc'ed
>    b) Prefer to cc a suitable mailing list as well
>    c) Ideally: find the original patch on the mailing list and do a
>       reply-to-all to that, adding suitable additional cc's
> 
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
> 
> The -mm tree is included into linux-next via the mm-everything
> branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
> and is updated there every 2-3 working days
> 
> ------------------------------------------------------
> From: Alex Williamson <alex.williamson@redhat.com>
> Subject: mm: re-allow pinning of zero pfns (again)
> Date: Wed, 10 Aug 2022 10:53:59 -0600
> 
> The below referenced commit makes the same error as 1c563432588d ("mm: fix
> is_pinnable_page against a cma page"), re-interpreting the logic to
> exclude pinning of the zero page, which breaks device assignment with
> vfio.
> 
> To avoid further subtle mistakes, split the logic into discrete tests.
> 
> Link: https://lkml.kernel.org/r/166015037385.760108.16881097713975517242.stgit@omen
> Link: https://lore.kernel.org/all/165490039431.944052.12458624139225785964.stgit@omen
> Fixes: f25cbb7a95a2 ("mm: add zone device coherent type memory support")
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> Suggested-by: Matthew Wilcox <willy@infradead.org>
> Suggested-by: Felix Kuehling <felix.kuehling@amd.com>
> Cc: Alex Sierra <alex.sierra@amd.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Alistair Popple <apopple@nvidia.com>
> Cc: David Hildenbrand <david@redhat.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Reviewed-by: David Hildenbrand <david@redhat.com>


-- 
Thanks,

David / dhildenb

+ mm-re-allow-pinning-of-zero-pfns-again.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: re-allow pinning of zero pfns (again)
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-re-allow-pinning-of-zero-pfns-again.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-re-allow-pinning-of-zero-pfns-again.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Alex Williamson <alex.williamson@redhat.com>
Subject: mm: re-allow pinning of zero pfns (again)
Date: Wed, 10 Aug 2022 10:53:59 -0600

The below referenced commit makes the same error as 1c563432588d ("mm: fix
is_pinnable_page against a cma page"), re-interpreting the logic to
exclude pinning of the zero page, which breaks device assignment with
vfio.

To avoid further subtle mistakes, split the logic into discrete tests.

Link: https://lkml.kernel.org/r/166015037385.760108.16881097713975517242.stgit@omen
Link: https://lore.kernel.org/all/165490039431.944052.12458624139225785964.stgit@omen
Fixes: f25cbb7a95a2 ("mm: add zone device coherent type memory support")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Suggested-by: Felix Kuehling <felix.kuehling@amd.com>
Cc: Alex Sierra <alex.sierra@amd.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/mm.h |   17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

--- a/include/linux/mm.h~mm-re-allow-pinning-of-zero-pfns-again
+++ a/include/linux/mm.h
@@ -1544,9 +1544,20 @@ static inline bool is_longterm_pinnable_
 	if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE)
 		return false;
 #endif
-	return !(is_device_coherent_page(page) ||
-		 is_zone_movable_page(page) ||
-		 is_zero_pfn(page_to_pfn(page)));
+	/*
+	 * The zero page might reside in a movable zone, however it may not
+	 * be migrated and can therefore be pinned.  The vfio subsystem pins
+	 * user mappings including the zero page for IOMMU translation.
+	 */
+	if (is_zero_pfn(page_to_pfn(page)))
+		return true;
+
+	/* Coherent device memory must always allow eviction. */
+	if (is_device_coherent_page(page))
+		return false;
+
+	/* Otherwise, non-movable zone pages can be pinned. */
+	return !is_zone_movable_page(page);
 }
 #else
 static inline bool is_longterm_pinnable_page(struct page *page)
_

Patches currently in -mm which might be from alex.williamson@redhat.com are

mm-re-allow-pinning-of-zero-pfns-again.patch