mm/rmap: separate out fork-only logic on anon_vma_clone()

Specify which operation is being performed to anon_vma_clone(), which
allows us to do checks specific to each operation type, as well as to
separate out and make clear that the anon_vma reuse logic is absolutely
specific to fork only.

This opens the door to further refactorings and refinements later as we
have more information to work with.

Link: https://lkml.kernel.org/r/cf7da7a2d973cdc72a1b80dd9a73260519e8fa9f.1768746221.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chris Li <chriscli@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/mm/vma.c b/mm/vma.c
index 6c458c8656b8..3dbe414eff89 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -530,7 +530,7 @@ __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	if (err)
 		goto out_free_vmi;
 
-	err = anon_vma_clone(new, vma);
+	err = anon_vma_clone(new, vma, VMA_OP_SPLIT);
 	if (err)
 		goto out_free_mpol;
 
@@ -628,7 +628,7 @@ static int dup_anon_vma(struct vm_area_struct *dst,
 
 		vma_assert_write_locked(dst);
 		dst->anon_vma = src->anon_vma;
-		ret = anon_vma_clone(dst, src);
+		ret = anon_vma_clone(dst, src, VMA_OP_MERGE_UNFAULTED);
 		if (ret)
 			return ret;
 
@@ -1901,7 +1901,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 		vma_set_range(new_vma, addr, addr + len, pgoff);
 		if (vma_dup_policy(vma, new_vma))
 			goto out_free_vma;
-		if (anon_vma_clone(new_vma, vma))
+		if (anon_vma_clone(new_vma, vma, VMA_OP_REMAP))
 			goto out_free_mempol;
 		if (new_vma->vm_file)
 			get_file(new_vma->vm_file);