Re: possible deadlock in console_unlock

From: Yao HongBo
Date: Mon Feb 18 2019 - 21:49:56 EST

On 2/19/2019 9:32 AM, Sergey Senozhatsky wrote:
> 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.
> Hello,
>> I merged this patch series on linux-4.19.18, but it didn't work for the fault-injection cases.
> Thanks!
>> 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.
> BTW,
> we are now looking at a completely new printk implementation; which
> would not use printk_safe at all:

Ok, i understand it.
Anyway, thank you for your help.
Best regards,

> -ss