Re: [PATCH] mm,hwpoison: non-current task should be checked early_kill for force_early

[Aili Yao <yaoaili@kingsoft.com>]

On Mon, 18 Jan 2021 08:57:47 +0000
HORIGUCHI NAOYA(堀口　直也) <naoya.horiguchi@nec.com> wrote:

> > > 
> > > For action optional cases, one error event kills *only one* process. If an
> > > error page are shared by multiple processes, these processes will be killed
> > > by separate error events, each of which is triggered when each process tries
> > > to access the error memory.  So these processes would be killed immediately
> > > when accessing the error, but you don't have to kill all at the same time
> > > (or actually you might not even have to kill it at all if the process exits
> > > finally without accessing the error later).
> > > 
> > > Maybe the function variable "force_early" is named confusingly (it sounds
> > > that it's related to PF_MCE_KILL_EARLY flag, but that's incorrect).
> > > I'll submit a fix later.  (I'll add your "Reported-by" because you made me
> > > find it, thank you.)
> > >   
> > I think we should do more for non current process error case, we should mark it AO for processes to be signaled
> > or we may take wrong action.  
> 
> I'm not sure what you mean by "non current process error case" and "we
> should mark it AO", so could you explain more specifically about your error
> scenario?  
  I will share my test code and i will submit another patch to this scenario.
  please give me some time, thanks!
  And I think you are right, AR is only current process.

> Especially I'd like to know about who triggers hard offline on
> what hardware events and what "wrong action" could happen.  Maybe just
> "calling memory_failure() with MF_ACTION_REQUIRED" is not enough, because
> it's not enough for us to see that your scenario is possible. Current
> implementation implicitly assumes some hardware behavior, and does not work
> for the case which never happens under the assumption.
> 
  This action is from mcelog daemon, normally softpage offlie is default, but we can configure
hardpage offline for CE storms, to get related processes signaled.

> Do you have some test cases to reproduce any specific issue (like data lost)
> on your system? (If yes, please share it.) Or your concern is from code review?
>
  I will make it clean, get it shared

Thanks
-- 
Best Regards!

Aili Yao