The patch titled
Subject: nommu: fix split_vma() map_count error
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
nommu-fix-split_vma-map_count-error.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/nommu-fix-split_vma-map_count-error.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Liam Howlett <liam.howlett@xxxxxxxxxx>
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@xxxxxxxxxx
Fixes: 8220543df148 ("nommu: remove uses of VMA linked list")
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxx are
nommu-fix-memory-leak-in-do_mmap-error-path.patch
nommu-fix-do_munmap-error-path.patch
nommu-fix-split_vma-map_count-error.patch
maple_tree-remove-gfp_zero-from-kmem_cache_alloc-and-kmem_cache_alloc_bulk.patch
