block: directly insert blk-mq request from blk_insert_cloned_request()

[mirror_ubuntu-bionic-kernel.git] / mm / mremap.c

diff --git a/mm/mremap.c b/mm/mremap.c
index 3f23715d3c692770193ff99e707131d95369065c..cfec004c4ff9a95511940039d6975d270bf37996 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -223,7 +223,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
                new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
                if (!new_pmd)
                        break;
-               if (pmd_trans_huge(*old_pmd)) {
+               if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd)) {
                        if (extent == HPAGE_PMD_SIZE) {
                                bool moved;
                                /* See comment in move_ptes() */
@@ -384,6 +384,19 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
        if (!vma || vma->vm_start > addr)
                return ERR_PTR(-EFAULT);
 
+       /*
+        * !old_len is a special case where an attempt is made to 'duplicate'
+        * a mapping.  This makes no sense for private mappings as it will
+        * instead create a fresh/new mapping unrelated to the original.  This
+        * is contrary to the basic idea of mremap which creates new mappings
+        * based on the original.  There are no known use cases for this
+        * behavior.  As a result, fail such attempts.
+        */
+       if (!old_len && !(vma->vm_flags & (VM_SHARED | VM_MAYSHARE))) {
+               pr_warn_once("%s (%d): attempted to duplicate a private mapping with mremap.  This is not supported.\n", current->comm, current->pid);
+               return ERR_PTR(-EINVAL);
+       }
+
        if (is_vm_hugetlb_page(vma))
                return ERR_PTR(-EINVAL);