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[PATCHv2,22/59] mm/rmap: Clear vma->anon_vma on unlink_anon_vmas()

Message ID 20190731150813.26289-23-kirill.shutemov@linux.intel.com
State New, archived
Headers show
Series Intel MKTME enabling | expand

Commit Message

Kirill A. Shutemov July 31, 2019, 3:07 p.m. UTC
If all pages in the VMA got unmapped there's no reason to link it into
original anon VMA hierarchy: it cannot possibly share any pages with
other VMA.

Set vma->anon_vma to NULL on unlink_anon_vmas(). With the change VMA
can be reused. The new anon VMA will be allocated on the first fault.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 mm/rmap.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
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Patch

diff --git a/mm/rmap.c b/mm/rmap.c
index e5dfe2ae6b0d..911367b5fb40 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -400,8 +400,10 @@  void unlink_anon_vmas(struct vm_area_struct *vma)
 		list_del(&avc->same_vma);
 		anon_vma_chain_free(avc);
 	}
-	if (vma->anon_vma)
+	if (vma->anon_vma) {
 		vma->anon_vma->degree--;
+		vma->anon_vma = NULL;
+	}
 	unlock_anon_vma_root(root);
 
 	/*