From: Liam Howlett liam.howlett@oracle.com
commit fd9edbdbdcde6b489ce59f326755ef16a2ffadd7 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/nommu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/nommu.c b/mm/nommu.c index 844af5be7640..5b83938ecb67 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -559,7 +559,6 @@ void vma_mas_remove(struct vm_area_struct *vma, struct ma_state *mas)
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_state *mas, struct mm_struct *mm, 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, struct vm_area_struct *vma, 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, struct vm_area_struct *vma, 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: