From da27c9ed17794b4741fe2858ce727ffac671877e Mon Sep 17 00:00:00 2001 From: "Uladzislau Rezki (Sony)" Date: Thu, 6 Aug 2020 23:24:12 -0700 Subject: [PATCH] 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. Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Andrew Morton Link: http://lkml.kernel.org/r/20200527205054.1696-2-urezki@gmail.com Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 42 ++++++++---------------------------------- 1 file changed, 8 insertions(+), 34 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d0ec02308d7c..740b7e4cac03 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -633,43 +633,17 @@ unlink_va(struct vmap_area *va, struct rb_root *root) #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; + unsigned long computed_size; - if (n == NULL) - return; - - va = rb_entry(n, struct vmap_area, rb_node); - size = va->subtree_max_size; - node = n; - - 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_area *va) } #if DEBUG_AUGMENT_PROPAGATE_CHECK - augment_tree_propagate_check(free_vmap_area_root.rb_node); + augment_tree_propagate_check(); #endif }