[PATCH v4 06/21] mm/vma: remove superfluous map->hold_file_rmap_lock

Lorenzo Stoakes (Oracle)
2026-03-20T22:40:23Z

We don't need to reference this field, it's confusing as it duplicates
mmap_action->hide_from_rmap_until_complete, so thread the mmap_action
through to __mmap_new_vma() instead and use the same field consistently.

Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
---
mm/vma.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/mm/vma.c b/mm/vma.c
index 3fc5fe4f1a7c..6105f54cea61 100644
--- a/mm/vma.c
+++ b/mm/vma.c
@@ -38,8 +38,6 @@ struct mmap_state {

/* Determine if we can check KSM flags early in mmap() logic. */
bool check_ksm_early :1;
- /* If we map new, hold the file rmap lock on mapping. */
- bool hold_file_rmap_lock :1;
/* If .mmap_prepare changed the file, we don't need to pin. */
bool file_doesnt_need_get :1;
};
@@ -2531,10 +2529,12 @@ static int __mmap_new_file_vma(struct mmap_state *map,
*
* @map: Mapping state.
* @vmap: Output pointer for the new VMA.
+ * @action: Any mmap_prepare action that is still to complete.
*
* Returns: Zero on success, or an error.
*/
-static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap)
+static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap,
+ struct mmap_action *action)
{
struct vma_iterator *vmi = map->vmi;
int error = 0;
@@ -2583,7 +2583,7 @@ static int __mmap_new_vma(struct mmap_state *map, struct vm_area_struct **vmap)
vma_start_write(vma);
vma_iter_store_new(vmi, vma);
map->mm->map_count++;
- vma_link_file(vma, map->hold_file_rmap_lock);
+ vma_link_file(vma, action->hide_from_rmap_until_complete);

/*
* vma_merge_new_range() calls khugepaged_enter_vma() too, the below
@@ -2650,8 +2650,6 @@ static int call_action_prepare(struct mmap_state *map,
if (err)
return err;

- if (desc->action.hide_from_rmap_until_complete)
- map->hold_file_rmap_lock = true;
return 0;
}

@@ -2741,7 +2739,7 @@ static int call_action_complete(struct mmap_state *map,
err = mmap_action_complete(vma, action);

/* If we held the file rmap we need to release it. */
- if (map->hold_file_rmap_lock) {
+ if (action->hide_from_rmap_until_complete) {
struct file *file = vma->vm_file;

i_mmap_unlock_write(file->f_mapping);
@@ -2795,7 +2793,7 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr,

/* ...but if we can't, allocate a new VMA. */
if (!vma) {
- error = __mmap_new_vma(&map, &vma);
+ error = __mmap_new_vma(&map, &vma, &desc.action);
if (error)
goto unacct_error;
allocated_new = true;
--
2.53.0