Messages in this thread | | | Date | Mon, 3 Dec 2018 14:40:17 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] Revert "exec: make de_thread() freezable (was: Re: Linux 4.20-rc4) |
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On 12/03, 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. > > So can we find a way to shut the lockdep up
You have already mentioned freezable_schedule_unsafe(), but I agree with "DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION" above it ...
> when this is not really a > deadlock?
not a deadlock, but lockdep is obviously right, suspend still can fail if another task needs the same mutex.
Again, we have already discussed this, in my opinion we should blame exec/ de_thread for this and other problems.
> Or maybe this really is one and then we need a real fix for > stable as well.
Well, strace -f can hang if it races with mt exec, it would be nice to have a fix for stable.
Oleg.
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