mm: handle write faults to RO pages under the VMA lock

I think this is a pretty rare occurrence, but for consistency handle
faults with the VMA lock held the same way that we handle other faults
with the VMA lock held.

Link: https://lkml.kernel.org/r/20231006195318.4087158-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/memory.c b/mm/memory.c
index ada461b82a75b2ad3f5eecfe25cd63e7fe412370..ceffe96f2a0e335e4441ff75877bbc3893851fa4 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3301,10 +3301,9 @@ static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
                vm_fault_t ret;
 
                pte_unmap_unlock(vmf->pte, vmf->ptl);
-               if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
-                       vma_end_read(vmf->vma);
-                       return VM_FAULT_RETRY;
-               }
+               ret = vmf_can_call_fault(vmf);
+               if (ret)
+                       return ret;
 
                vmf->flags |= FAULT_FLAG_MKWRITE;
                ret = vma->vm_ops->pfn_mkwrite(vmf);
@@ -3328,10 +3327,10 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf, struct folio *folio)
                vm_fault_t tmp;
 
                pte_unmap_unlock(vmf->pte, vmf->ptl);
-               if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
+               tmp = vmf_can_call_fault(vmf);
+               if (tmp) {
                        folio_put(folio);
-                       vma_end_read(vmf->vma);
-                       return VM_FAULT_RETRY;
+                       return tmp;
                }
 
                tmp = do_page_mkwrite(vmf, folio);