diff mbox series

[v2,9/9] mm/mshare: Enable mshare region mapping across processes

Message ID 9dc1848f0fcbe3abe3d22584e339f2dfee60cb32.1656531090.git.khalid.aziz@oracle.com (mailing list archive)
State New
Headers show
Series Add support for shared PTEs across processes | expand

Commit Message

Khalid Aziz June 29, 2022, 10:54 p.m. UTC 
This patch enables propcesses that did not create the mshare region
to map the region using mmap().

Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
---
 mm/mshare.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/mm/mshare.c b/mm/mshare.c
index 2ec0e56ffd69..455b10ca0cdf 100644
--- a/mm/mshare.c
+++ b/mm/mshare.c
@@ -144,7 +144,21 @@  msharefs_mmap(struct file *file, struct vm_area_struct *vma)
 	 * page table sharing
 	 */
 	if (new_mm->mmap_base != 0) {
-		return -EINVAL;
+		/*
+		 * Any mappings of mshare region must use exact same
+		 * virtual addresses
+		 */
+		if ((vma->vm_start != new_mm->mmap_base) ||
+			(new_mm->task_size != (vma->vm_end - vma->vm_start)))
+			return -EINVAL;
+
+		vma->vm_private_data = info;
+		/*
+		 * mshare pages are shared pages that also share page table
+		 */
+		vma->vm_flags |= (VM_SHARED_PT|VM_SHARED);
+		vma->vm_ops = &msharefs_vm_ops;
+		refcount_inc(&info->refcnt);
 	} else {
 		struct mm_struct *old_mm;
 		struct vm_area_struct *new_vma;