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-rw-r--r--include/linux/mm.h2
-rw-r--r--mm/pagewalk.c3
2 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6321e840e21d..3c5505a3bc49 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -911,6 +911,8 @@ unsigned long unmap_vmas(struct mmu_gather *tlb,
* @pte_entry: if set, called for each non-empty PTE (4th-level) entry
* @pte_hole: if set, called for each hole at all levels
* @hugetlb_entry: if set, called for each hugetlb entry
+ * *Caution*: The caller must hold mmap_sem() if @hugetlb_entry
+ * is used.
*
* (see walk_page_range for more details)
*/
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index ee4ff87c58c1..f7929406e776 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -181,6 +181,9 @@ static int walk_hugetlb_range(struct vm_area_struct *vma,
*
* If any callback returns a non-zero value, the walk is aborted and
* the return value is propagated back to the caller. Otherwise 0 is returned.
+ *
+ * walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry
+ * is !NULL.
*/
int walk_page_range(unsigned long addr, unsigned long end,
struct mm_walk *walk)