[PATCH v2 3/6] mm/mprotect: Replace can_modify_mm with can_modify_vma

[Pedro Falcato <pedro.falcato@gmail.com>]

Avoid taking an extra trip down the mmap tree by checking the vmas
directly. mprotect (per POSIX) tolerates partial failure.

Signed-off-by: Pedro Falcato <pedro.falcato@gmail.com>
---
 mm/mprotect.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 37cf8d24940..11330131e2b 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -588,6 +588,9 @@ mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb,
 	unsigned long charged = 0;
 	int error;
 
+	if (!can_modify_vma(vma))
+		return -EPERM;
+
 	if (newflags == oldflags) {
 		*pprev = vma;
 		return 0;
@@ -746,15 +749,6 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 		}
 	}
 
-	/*
-	 * checking if memory is sealed.
-	 * can_modify_mm assumes we have acquired the lock on MM.
-	 */
-	if (unlikely(!can_modify_mm(current->mm, start, end))) {
-		error = -EPERM;
-		goto out;
-	}
-
 	prev = vma_prev(&vmi);
 	if (start > vma->vm_start)
 		prev = vma;
-- 
2.46.0