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mm/vmalloc: simplify augment_tree_propagate_check()

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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) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200527205054.1696-2-urezki@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Uladzislau Rezki (Sony) 2020-08-06 23:24:12 -07:00 committed by Linus Torvalds
parent 5dd7864094
commit da27c9ed17
1 changed files with 8 additions and 34 deletions
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38
mm/vmalloc.c
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@ -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;
}
}
if (!found) {
va = rb_entry(n, struct vmap_area, rb_node);
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);
}
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
}