[PATCH 01/22] mm: Add vma_lookup()
liam.howlett at oracle.com
Mon May 10 09:58:49 PDT 2021
Many places in the kernel use find_vma() to get a vma and then check the
start address of the vma to ensure the next vma was not returned.
Other places use the find_vma_intersection() call with add, addr + 1 as
the range; looking for just the vma at a specific address.
The third use of find_vma() is by developers who do not know that the
function starts searching at the provided address upwards for the next
vma. This results in a bug that is often overlooked for a long time.
Adding the new vma_lookup() function will allow for cleaner code by
removing the find_vma() calls which check limits, making
find_vma_intersection() calls of a single address to be shorter, and
potentially reduce the incorrect uses of find_vma().
Signed-off-by: Liam R. Howlett <Liam.Howlett at Oracle.com>
include/linux/mm.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 25b9041f9925..5f2a15e702ff 100644
@@ -2689,6 +2689,24 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m
+ * vma_lookup() - Find a VMA at a specific address
+ * @mm: The process address space.
+ * @addr: The user address.
+ * Return: The vm_area_struct at the given address, %NULL otherwise.
+struct vm_area_struct *vma_lookup(struct mm_struct *mm, unsigned long addr)
+ struct vm_area_struct * vma = find_vma(mm, addr);
+ if (vma && addr < vma->vm_start)
+ vma = NULL;
+ return vma;
static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
unsigned long vm_start = vma->vm_start;
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