The added shrinker is used to return back current cached VAs into a global vmap space, when a system enters into a low memory mode. Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> --- mm/vmalloc.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ef534c76daef..e30dabf68263 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4917,8 +4917,37 @@ static void vmap_init_nodes(void) } } +static unsigned long +vmap_node_shrink_count(struct shrinker *shrink, struct shrink_control *sc) +{ + unsigned long count; + struct vmap_node *vn; + int i, j; + + for (count = 0, i = 0; i < nr_vmap_nodes; i++) { + vn = &vmap_nodes[i]; + + for (j = 0; j < MAX_VA_SIZE_PAGES; j++) + count += READ_ONCE(vn->pool[j].len); + } + + return count ? count : SHRINK_EMPTY; +} + +static unsigned long +vmap_node_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) +{ + int i; + + for (i = 0; i < nr_vmap_nodes; i++) + decay_va_pool_node(&vmap_nodes[i], true); + + return SHRINK_STOP; +} + void __init vmalloc_init(void) { + struct shrinker *vmap_node_shrinker; struct vmap_area *va; struct vmap_node *vn; struct vm_struct *tmp; @@ -4966,4 +4995,14 @@ void __init vmalloc_init(void) */ vmap_init_free_space(); vmap_initialized = true; + + vmap_node_shrinker = shrinker_alloc(0, "vmap-node"); + if (!vmap_node_shrinker) { + pr_err("Failed to allocate vmap-node shrinker!\n"); + return; + } + + vmap_node_shrinker->count_objects = vmap_node_shrink_count; + vmap_node_shrinker->scan_objects = vmap_node_shrink_scan; + shrinker_register(vmap_node_shrinker); } -- 2.39.2