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Subject[PATCH v4 2/3] mm/vmap: add DEBUG_AUGMENT_PROPAGATE_CHECK macro
Date
This macro adds some debug code to check that the augment tree
is maintained correctly, meaning that every node contains valid
subtree_max_size value.

By default this option is set to 0 and not active. It requires
recompilation of the kernel to activate it. Set to 1, compile
the kernel.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
---
mm/vmalloc.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index c6f9d0637464..a74e605e042f 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -324,6 +324,8 @@ EXPORT_SYMBOL(vmalloc_to_pfn);

/*** Global kva allocator ***/

+#define DEBUG_AUGMENT_PROPAGATE_CHECK 0
+
#define VM_LAZY_FREE 0x02
#define VM_VM_AREA 0x04

@@ -538,6 +540,48 @@ 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)
+{
+ 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;
+
+ 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);
+ 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
+
/*
* This function populates subtree_max_size from bottom to upper
* levels starting from VA point. The propagation must be done
@@ -587,6 +631,10 @@ augment_tree_propagate_from(struct vmap_area *va)
va->subtree_max_size = new_va_sub_max_size;
node = rb_parent(&va->rb_node);
}
+
+#if DEBUG_AUGMENT_PROPAGATE_CHECK
+ augment_tree_propagate_check(free_vmap_area_root.rb_node);
+#endif
}

static void
--
2.11.0
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