On Mon 2018-12-03 15:17:37, Michal Hocko wrote: > On Mon 03-12-18 15:14:59, Pavel Machek wrote: > > On Mon 2018-12-03 14:53:51, Michal Hocko wrote: > > > On Mon 03-12-18 14:10:06, Pavel Machek wrote: > > > > On Mon 2018-12-03 13:38:57, Michal Hocko wrote: > > > > > On Mon 03-12-18 13:31:49, Oleg Nesterov wrote: > > > > > > On 12/03, Michal Hocko wrote: > > > > > > > > > > > > > > Now, I wouldn't mind to revert this because the code is really > > > > > > > old and > > > > > > > we haven't seen many bug reports about failing suspend yet. But > > > > > > > what is > > > > > > > the actual plan to make this work properly? > > > > > > > > > > > > I don't see a simple solution... > > > > > > > > > > > > But we need to fix exec/de_thread anyway, then we can probably > > > > > > reconsider > > > > > > this patch. > > > > > > > > > > My concern is that de_thread fix might be too disruptive for stable > > > > > kernels while we might want to have a simple enough fix for the the > > > > > suspend issue in the meantime. That was actually the primary reason > > > > > I've > > > > > acked the hack even though I didn't like it. > > > > > > > > Do we care about failing sleep in stable? Does someone hit the issue > > > > there? > > > > > > > > This sounds like issue only Android is hitting, and they run very > > > > heavily patched kernels, far away from mainline or stable. > > > > > > But the underlying issue is the same and independent on their patches > > > AFAIU. And is this really a common problem to care about in stable? I > > > dunno to be honest but it sounds annoying for sure. Failing suspend is > > > something that doesn't make your day when you are in hurry and want > > > find out only later when your laptop heats up your bag ;) > > > > In general, yes. In practice, if it happens 1 in 1000000 suspends, you > > don't care that much (but Android cares). > > This argument just doesn't make any sense. Rare bugs are maybe even > more
I guess argumenting about this just does not make sense. Just bear in
mind -stable is not for theoretical problems.
> annoying because you do not expect them to happen. But I would be more
> interested to see whether they are any downside. Is there any actual
> risk to silence the lockup detector that you can see?
As someone else noticed:
a) the bug can be triggered outside suspend
b) the lockdep report is real. You'll still get suspend failure, but
you now need two processes to trigger it
> > Do we actually have reports of this happening for people outside
> > Android?
>
> Not that I am aware of.
Good.
Pavel
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