I'm trying to implement a red/black tree in Linux per task_struct using code from linux/rbtree.h. I can get a red/black tree inserting properly in a standalone space in the kernel such as a module but when I try to get the same code to function with the rb_root declared in either task_struct or task_struct->files_struct, I get a SEGFAULT everytime I try an insert.

Here's some code:

In task_struct I create a rb_root struct for my tree (not a pointer). In init_task.h, macro INIT_TASK(tsk), I set this equal to RB_ROOT. To do an insert, I use this code: rb_insert(&(current->fd_tree), &rbnode); This is where the issue occurs.

My insert command is the standard insert that is documented in all RBTree documentation for the kernel:

  int my_insert(struct rb_root *root, struct mytype *data)
  {
    struct rb_node **new = &(root->rb_node), *parent = NULL;

    /* Figure out where to put new node */
    while (*new) {
        struct mytype *this = container_of(*new, struct mytype, node);
        int result = strcmp(data->keystring, this->keystring);

        parent = *new;
        if (result < 0)
            new = &((*new)->rb_left);
        else if (result > 0)
            new = &((*new)->rb_right);
        else
            return FALSE;
    }

    /* Add new node and rebalance tree. */
    rb_link_node(&data->node, parent, new);
    rb_insert_color(&data->node, root);

    return TRUE;
  }

Is there something I'm missing? Some reason this would work fine if I made a tree root outside of task_struct? If I make rb_root inside of a module this insert works fine. But once I put the actual tree root in the task_struct or even in the task_struct->files_struct, I get a SEGFAULT. Can a root node not be added in these structs? Any tips are greatly appreciated. I've tried nearly everything I can think of.