Re: possible deadlock in console_unlock

From: Sergey Senozhatsky
Date: Mon Feb 18 2019 - 20:33:02 EST

On (02/18/19 22:07), Yao HongBo wrote:
> >> I have tried GFP_NOWARN, but the problem still exists.
> >> Only print_safe contexts for tty locks can solve the problem.
> >> My test scenario is falt-injection.
> >
> > Oh, I see. Yes, fault-injection is special.
> >
> > I suspect that this patch series can be helpful then
> >
> hi, sergey.


> I merged this patch series on linux-4.19.18, but it didn't work for the fault-injection cases.


> The failure seems to be the same as before.

OK... So tty_port lock must switch to printk_safe, after all...
I had it in one of the previous versions of the patchset which you
have tested, but people were strictly against new locking rules
in TTY, so I dropped that part. Need to think what we can do here.

we are now looking at a completely new printk implementation; which
would not use printk_safe at all: