Messages in this thread |  | | Date | Fri, 17 Jul 2009 18:43:46 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC PATCH] kmemleak: Scan all thread stacks |
| |
* Catalin Marinas <catalin.marinas@arm.com> wrote:
> This patch changes the for_each_process() loop with the > do_each_thread()/while_each_thread() pair. It also replaces the > read_lock(&tasklist_lock) with rcu_read_lock() and task_lock(p). > > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > --- > > My questions: > > 1. Is it correct that for_each_process() used currently by kmemleak may > not loop through all the possible kernel thread stacks?
yes. You need the full, all tasks variant:
do_each_thread(g, p) { ... } while_each_thread(g, p);
> 2. Is it safe to use rcu_read_lock() and task_lock() when scanning the > corresponding kernel stack (thread_info structure)? The loop doesn't > do any modification to the task list. The reason for this is to > allow kernel preemption when scanning the stacks.
you cannot generally preempt while holding the RCU read-lock.
Ingo
|  |