[merged] mm-mmap-merge-vma-after-call_mmap-if-possible.patch removed from -mm tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



The patch titled
     Subject: mm: mmap: merge vma after call_mmap() if possible
has been removed from the -mm tree.  Its filename was
     mm-mmap-merge-vma-after-call_mmap-if-possible.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm: mmap: merge vma after call_mmap() if possible

The vm_flags may be changed after call_mmap() because drivers may set some
flags for their own purpose.  As a result, we failed to merge the adjacent
vma due to the different vm_flags as userspace can't pass in the same one.
Try to merge vma after call_mmap() to fix this issue.

Link: http://lkml.kernel.org/r/1594954065-23733-1-git-send-email-linmiaohe@xxxxxxxxxx
Signed-off-by: Hongxiang Lou <louhongxiang@xxxxxxxxxx>
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/mmap.c |   22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

--- a/mm/mmap.c~mm-mmap-merge-vma-after-call_mmap-if-possible
+++ a/mm/mmap.c
@@ -1690,7 +1690,7 @@ unsigned long mmap_region(struct file *f
 		struct list_head *uf)
 {
 	struct mm_struct *mm = current->mm;
-	struct vm_area_struct *vma, *prev;
+	struct vm_area_struct *vma, *prev, *merge;
 	int error;
 	struct rb_node **rb_link, *rb_parent;
 	unsigned long charged = 0;
@@ -1774,6 +1774,25 @@ unsigned long mmap_region(struct file *f
 		if (error)
 			goto unmap_and_free_vma;
 
+		/* If vm_flags changed after call_mmap(), we should try merge vma again
+		 * as we may succeed this time.
+		 */
+		if (unlikely(vm_flags != vma->vm_flags && prev)) {
+			merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
+				NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX);
+			if (merge) {
+				fput(file);
+				vm_area_free(vma);
+				vma = merge;
+				/* Update vm_flags and possible addr to pick up the change. We don't
+				 * warn here if addr changed as the vma is not linked by vma_link().
+				 */
+				addr = vma->vm_start;
+				vm_flags = vma->vm_flags;
+				goto unmap_writable;
+			}
+		}
+
 		/* Can addr have changed??
 		 *
 		 * Answer: Yes, several device drivers can do it in their
@@ -1796,6 +1815,7 @@ unsigned long mmap_region(struct file *f
 	vma_link(mm, vma, prev, rb_link, rb_parent);
 	/* Once vma denies write, undo our temporary denial count */
 	if (file) {
+unmap_writable:
 		if (vm_flags & VM_SHARED)
 			mapping_unmap_writable(file->f_mapping);
 		if (vm_flags & VM_DENYWRITE)
_

Patches currently in -mm which might be from linmiaohe@xxxxxxxxxx are





[Index of Archives]     [Kernel Archive]     [IETF Annouce]     [DCCP]     [Netdev]     [Networking]     [Security]     [Bugtraq]     [Yosemite]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux SCSI]

  Powered by Linux