[merged mm-stable] fs-proc-extend-the-pagemap_scan-ioctl-to-report-guard-regions.patch removed from -mm tree

[merged mm-stable] fs-proc-extend-the-pagemap_scan-ioctl-to-report-guard-regions.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions
has been removed from the -mm tree.  Its filename was
     fs-proc-extend-the-pagemap_scan-ioctl-to-report-guard-regions.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Andrei Vagin <avagin@gmail.com>
Subject: fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions
Date: Mon, 24 Mar 2025 06:53:26 +0000

Patch series "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard
regions", v2.

Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose
information about guard regions.  This allows userspace tools, such as
CRIU, to detect and handle guard regions.

Currently, CRIU utilizes PAGEMAP_SCAN as a more efficient alternative to
parsing /proc/pid/pagemap.  Without this change, guard regions are
incorrectly reported as swap-anon regions, leading CRIU to attempt dumping
them and subsequently failing.

The series includes updates to the documentation and selftests to reflect
the new functionality.


This patch (of 3):

Introduce the PAGE_IS_GUARD flag in the PAGEMAP_SCAN ioctl to expose
information about guard regions.  This allows userspace tools, such as
CRIU, to detect and handle guard regions.

Link: https://lkml.kernel.org/r/20250324065328.107678-1-avagin@google.com
Link: https://lkml.kernel.org/r/20250324065328.107678-2-avagin@google.com
Signed-off-by: Andrei Vagin <avagin@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 Documentation/admin-guide/mm/pagemap.rst |    1 +
 fs/proc/task_mmu.c                       |   17 ++++++++++-------
 include/uapi/linux/fs.h                  |    1 +
 3 files changed, 12 insertions(+), 7 deletions(-)

--- a/Documentation/admin-guide/mm/pagemap.rst~fs-proc-extend-the-pagemap_scan-ioctl-to-report-guard-regions
+++ a/Documentation/admin-guide/mm/pagemap.rst
@@ -250,6 +250,7 @@ Following flags about pages are currentl
 - ``PAGE_IS_PFNZERO`` - Page has zero PFN
 - ``PAGE_IS_HUGE`` - Page is PMD-mapped THP or Hugetlb backed
 - ``PAGE_IS_SOFT_DIRTY`` - Page is soft-dirty
+- ``PAGE_IS_GUARD`` - Page is a part of a guard region
 
 The ``struct pm_scan_arg`` is used as the argument of the IOCTL.
 
--- a/fs/proc/task_mmu.c~fs-proc-extend-the-pagemap_scan-ioctl-to-report-guard-regions
+++ a/fs/proc/task_mmu.c
@@ -2087,7 +2087,8 @@ static int pagemap_release(struct inode
 #define PM_SCAN_CATEGORIES	(PAGE_IS_WPALLOWED | PAGE_IS_WRITTEN |	\
 				 PAGE_IS_FILE |	PAGE_IS_PRESENT |	\
 				 PAGE_IS_SWAPPED | PAGE_IS_PFNZERO |	\
-				 PAGE_IS_HUGE | PAGE_IS_SOFT_DIRTY)
+				 PAGE_IS_HUGE | PAGE_IS_SOFT_DIRTY |	\
+				 PAGE_IS_GUARD)
 #define PM_SCAN_FLAGS		(PM_SCAN_WP_MATCHING | PM_SCAN_CHECK_WPASYNC)
 
 struct pagemap_scan_private {
@@ -2128,12 +2129,14 @@ static unsigned long pagemap_page_catego
 		if (!pte_swp_uffd_wp_any(pte))
 			categories |= PAGE_IS_WRITTEN;
 
-		if (p->masks_of_interest & PAGE_IS_FILE) {
-			swp = pte_to_swp_entry(pte);
-			if (is_pfn_swap_entry(swp) &&
-			    !folio_test_anon(pfn_swap_entry_folio(swp)))
-				categories |= PAGE_IS_FILE;
-		}
+		swp = pte_to_swp_entry(pte);
+		if (is_guard_swp_entry(swp))
+			categories |= PAGE_IS_GUARD;
+		else if ((p->masks_of_interest & PAGE_IS_FILE) &&
+			 is_pfn_swap_entry(swp) &&
+			 !folio_test_anon(pfn_swap_entry_folio(swp)))
+			categories |= PAGE_IS_FILE;
+
 		if (pte_swp_soft_dirty(pte))
 			categories |= PAGE_IS_SOFT_DIRTY;
 	}
--- a/include/uapi/linux/fs.h~fs-proc-extend-the-pagemap_scan-ioctl-to-report-guard-regions
+++ a/include/uapi/linux/fs.h
@@ -361,6 +361,7 @@ typedef int __bitwise __kernel_rwf_t;
 #define PAGE_IS_PFNZERO		(1 << 5)
 #define PAGE_IS_HUGE		(1 << 6)
 #define PAGE_IS_SOFT_DIRTY	(1 << 7)
+#define PAGE_IS_GUARD		(1 << 8)
 
 /*
  * struct page_region - Page region with flags
_

Patches currently in -mm which might be from avagin@gmail.com are