mm/mmap: write-lock VMAs in vma_prepare before modifying them

Write-lock all VMAs which might be affected by a merge, split, expand or
shrink operations.  All these operations use vma_prepare() before making
the modifications, therefore it provides a centralized place to perform
VMA locking.

[surenb@google.com: remove unnecessary vp->vma check in vma_prepare]
Link: https://lkml.kernel.org/r/20230301022720.1380780-1-surenb@google.com
Link: https://lore.kernel.org/r/202302281802.J93Nma7q-lkp@intel.com/
Link: https://lkml.kernel.org/r/20230227173632.3292573-17-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Laurent Dufour <laurent.dufour@fr.ibm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index e8f019eecd0f128d53ef4e1b0acb4291ba859304..82999e0c3c31932223842a420ec13b226560b64c 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -502,6 +502,15 @@ static inline void init_vma_prep(struct vma_prepare *vp,
  */
 static inline void vma_prepare(struct vma_prepare *vp)
 {
+       vma_start_write(vp->vma);
+       if (vp->adj_next)
+               vma_start_write(vp->adj_next);
+       /* vp->insert is always a newly created VMA, no need for locking */
+       if (vp->remove)
+               vma_start_write(vp->remove);
+       if (vp->remove2)
+               vma_start_write(vp->remove2);
+
        if (vp->file) {
                uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end);