From: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx> Subject: mm/vmalloc: simplify augment_tree_propagate_check() This function is for debug purpose only. Currently it uses recursion for tree traversal, checking an augmented value of each node to find out if it is valid or not. The recursion can corrupt the stack because the tree can be huge if synthetic tests are applied. To prevent it, navigate the tree from bottom to upper levels using a regular list instead, because nodes are linked among each other also. It is faster and without recursion. Link: http://lkml.kernel.org/r/20200527205054.1696-2-urezki@xxxxxxxxx Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmalloc.c | 42 ++++++++---------------------------------- 1 file changed, 8 insertions(+), 34 deletions(-) --- a/mm/vmalloc.c~mm-vmalloc-simplify-augment_tree_propagate_check-func +++ a/mm/vmalloc.c @@ -633,43 +633,17 @@ unlink_va(struct vmap_area *va, struct r #if DEBUG_AUGMENT_PROPAGATE_CHECK static void -augment_tree_propagate_check(struct rb_node *n) +augment_tree_propagate_check(void) { struct vmap_area *va; - struct rb_node *node; - unsigned long size; - bool found = false; - - if (n == NULL) - return; - - va = rb_entry(n, struct vmap_area, rb_node); - size = va->subtree_max_size; - node = n; + unsigned long computed_size; - while (node) { - va = rb_entry(node, struct vmap_area, rb_node); - - if (get_subtree_max_size(node->rb_left) == size) { - node = node->rb_left; - } else { - if (va_size(va) == size) { - found = true; - break; - } - - node = node->rb_right; - } + list_for_each_entry(va, &free_vmap_area_list, list) { + computed_size = compute_subtree_max_size(va); + if (computed_size != va->subtree_max_size) + pr_emerg("tree is corrupted: %lu, %lu\n", + va_size(va), va->subtree_max_size); } - - if (!found) { - va = rb_entry(n, struct vmap_area, rb_node); - pr_emerg("tree is corrupted: %lu, %lu\n", - va_size(va), va->subtree_max_size); - } - - augment_tree_propagate_check(n->rb_left); - augment_tree_propagate_check(n->rb_right); } #endif @@ -724,7 +698,7 @@ augment_tree_propagate_from(struct vmap_ } #if DEBUG_AUGMENT_PROPAGATE_CHECK - augment_tree_propagate_check(free_vmap_area_root.rb_node); + augment_tree_propagate_check(); #endif } _
