[merged mm-hotfixes-stable] nommu-fix-split_vma-map_count-error.patch removed from -mm tree

[merged mm-hotfixes-stable] nommu-fix-split_vma-map_count-error.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: nommu: fix split_vma() map_count error
has been removed from the -mm tree.  Its filename was
     nommu-fix-split_vma-map_count-error.patch

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

------------------------------------------------------
From: Liam Howlett <liam.howlett@oracle.com>
Subject: nommu: fix split_vma() map_count error
Date: Mon, 9 Jan 2023 20:58:20 +0000

During the maple tree conversion of nommu, an error in counting the VMAs
was introduced by counting the existing VMA again.  The counting used to
be decremented by one and incremented by two, but now it only increments
by two.  Fix the counting error by moving the increment outside the
setup_vma_to_mm() function to the callers.

Link: https://lkml.kernel.org/r/20230109205809.956325-1-Liam.Howlett@oracle.com
Fixes: 8220543df148 ("nommu: remove uses of VMA linked list")
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/nommu.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/nommu.c~nommu-fix-split_vma-map_count-error
+++ a/mm/nommu.c
@@ -559,7 +559,6 @@ void vma_mas_remove(struct vm_area_struc
 
 static void setup_vma_to_mm(struct vm_area_struct *vma, struct mm_struct *mm)
 {
-	mm->map_count++;
 	vma->vm_mm = mm;
 
 	/* add the VMA to the mapping */
@@ -587,6 +586,7 @@ static void mas_add_vma_to_mm(struct ma_
 	BUG_ON(!vma->vm_region);
 
 	setup_vma_to_mm(vma, mm);
+	mm->map_count++;
 
 	/* add the VMA to the tree */
 	vma_mas_store(vma, mas);
@@ -1347,6 +1347,7 @@ int split_vma(struct mm_struct *mm, stru
 	if (vma->vm_file)
 		return -ENOMEM;
 
+	mm = vma->vm_mm;
 	if (mm->map_count >= sysctl_max_map_count)
 		return -ENOMEM;
 
@@ -1398,6 +1399,7 @@ int split_vma(struct mm_struct *mm, stru
 	mas_set_range(&mas, vma->vm_start, vma->vm_end - 1);
 	mas_store(&mas, vma);
 	vma_mas_store(new, &mas);
+	mm->map_count++;
 	return 0;
 
 err_mas_preallocate:
_

Patches currently in -mm which might be from liam.howlett@oracle.com are

maple_tree-fix-mas_empty_area_rev-lower-bound-validation.patch
maple_tree-remove-gfp_zero-from-kmem_cache_alloc-and-kmem_cache_alloc_bulk.patch