Re: lockdep trace from posix timers

[Oleg Nesterov]

On 08/20, Peter Zijlstra wrote:
>
>  task_work_cancel(struct task_struct *task, task_work_func_t func)
>  {
> ...
> +
> +again:
> +	workp = &task->task_works;
> +	work = *workp;
> +	while (work) {
> +		if (work->func == func) {

But this all can race with task_work_run() if task != current.

This "work" can be freed/reused. And it should only return !NULL
if twork->func() was not called.

Oleg.

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