On 02/22, Oleg Nesterov wrote: > > On 02/22, Rafael J. Wysocki wrote: > > > > @@ -207,7 +209,7 @@ static void thaw_tasks(int thaw_user_spa > > if (is_user_space(p) == !thaw_user_space) > > continue; > > > > - if (!thaw_process(p)) > > + if (!thaw_process(p) && !freezer_should_skip(p)) > > printk(KERN_WARNING " Strange, %s not stopped\n", > > This is racy, the warning could be false. We wake up the task, testing > its ->flags is not reliable. > > Damn. PF_FREEZER_SKIP task could be woken before, clear PF_FREEZER_SKIP, > but not frozen. > > We can change freezer_count() to clear PF_FREEZER_SKIP after try_to_freeze(), > not before. Now thaw_process() can take PF_FREEZER_SKIP into account and > return "true". > > But this means the task may be PF_FREEZER_SKIP | PF_FROZEN. What if we we > call try_to_freeze_tasks() soon after thaw_tasks()? We may hit the task which > leaves the refrigerator, but didn't clear PF_FREEZER_SKIP yet. This means > that thaw_process() should clear PF_FREEZER_SKIP as well. This is messy :( > > Any other ideas? In any case we should imho avoid a separate loop for > PF_FREEZER_SKIP tasks to just fix debug messages. In fact it can't help > anyway.
Probably: current clears PF_FREEZER_SKIP along with TIF_FREEZE "atomically" under task_lock in refrigerator(). thaw_process() takes PF_FREEZER_SKIP into account. Oleg. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
