Issue 20 in kedr: Test leak_check.kfree_rcu.01 freeze system

[ke...@googlecode.com]

Status: Accepted
Owner: tsy...@gmail.com
Labels: Type-Defect Priority-Medium

New issue 20 by tsy...@gmail.com: Test leak_check.kfree_rcu.01 freeze system
https://code.google.com/p/kedr/issues/detail?id=20

System becomes completely unresponsible few moments after the test
leak_check.kfree_rcu.01 begins.

Reproduced on OpenSUSE 13.1, Linux kernel 3.11.25 and 3.18.1(vanilla).
On previous distro-specific kernel (3.11.7 or near) the test has passed
successfully. Same for many others distro/kernel pairs.

Playing with tests/leak_check/kfree_rcu_module/test_module.c shows that
problems remains when code for 'foo' allocation/deallocation is removed,
but disappears when code for 'bar' is removed instead.
Without Leak Check given module is loaded/unloaded without errors.

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[ke...@googlecode.com]

Comment #1 on issue 20 by tsy...@gmail.com: Test leak_check.kfree_rcu.01
freeze system
https://code.google.com/p/kedr/issues/detail?id=20

Actually, problem persists only on 3.11.10-25 kernel, which is
distro-specific.
Investigation shows that problem is in dump_trace() call inside call_rcu()
callback.
Simple module demonstrates same behaviour(freeze system while loading):
--
#include <linux/module.h>
#include <linux/rcupdate.h>

MODULE_AUTHOR("Tsyvarev Andrey");
MODULE_LICENSE("GPL");

struct my_struct
{
struct rcu_head rh;
} s;

int a;

void rcu_func(struct rcu_head* head)
{
dump_stack();
a = 1;
}

static int my_module_init(void)
{
call_rcu(&s.rh, rcu_func);

return 0;
}
static void my_module_exit(void)
{
rcu_barrier();
}

module_init(my_module_init);
module_exit(my_module_exit);
--