Introduce per-vma begin()/end() helpers for pgtable walks. This is a
preparation work to merge hugetlb pgtable walkers with generic mm.
The helpers need to be called before and after a pgtable walk, will start
to be needed if the pgtable walker code supports hugetlb pages. It's a
hook point for any type of VMA, but for now only hugetlb uses it to
stablize the pgtable pages from getting away (due to possible pmd
unsharing).
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
include/linux/mm.h | 3 +++
mm/memory.c | 12 ++++++++++++
2 files changed, 15 insertions(+)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 64cd1ee4aacc..349232dd20fb 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -4154,4 +4154,7 @@ static inline bool pfn_is_unaccepted_memory(unsigned long pfn)
return range_contains_unaccepted_memory(paddr, paddr + PAGE_SIZE);
}
+void vma_pgtable_walk_begin(struct vm_area_struct *vma);
+void vma_pgtable_walk_end(struct vm_area_struct *vma);
+
#endif /* _LINUX_MM_H */
diff --git a/mm/memory.c b/mm/memory.c
index e27e2e5beb3f..3a6434b40d87 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -6180,3 +6180,15 @@ void ptlock_free(struct ptdesc *ptdesc)
kmem_cache_free(page_ptl_cachep, ptdesc->ptl);
}
#endif
+
+void vma_pgtable_walk_begin(struct vm_area_struct *vma)
+{
+ if (is_vm_hugetlb_page(vma))
+ hugetlb_vma_lock_read(vma);
+}
+
+void vma_pgtable_walk_end(struct vm_area_struct *vma)
+{
+ if (is_vm_hugetlb_page(vma))
+ hugetlb_vma_unlock_read(vma);
+}
--
2.41.0
