On 03/20, Michal Hocko wrote: > > On Wed 20-03-19 14:24:11, Oleg Nesterov wrote: > > On 03/20, Michal Hocko wrote: > > > > > > Yes we do hold the cgred mutex while calling freezable_schedule but why > > > are we getting a warning is not really clear to me. The task should be > > > hidden from the freezer so why do we warn at all? > > > > try_to_freeze() calls debug_check_no_locks_held() and this makes sense. > > Yes it does. But it already ignores PF_NOFREEZE tasks and I fail to see > why is PF_FREEZER_SKIP any different. But they differ. PF_NOFREEZE is a "sticky" flag for kthreads. Set by default, cleared by set_freezable() if you want a freezable kthread. PF_FREEZER_SKIP means that a sleeping freezable task will call try_to_freeze() right after schedule() returns, so try_to_freeze_tasks() can safely count it as "already frozen". > it seems that skipping the task was the only viable option > to fix suspend issues Yes, de_thread() should use freezable_schedule(), iow I hope we will reconsider this (reverted) patch. > as removing the cgred is way way too complicated. We need to do this anyway, this leads to other more serious problems... Oleg.
