Re: [PATCH v5 0/2] printk: Console owner and waiter logic cleanup

Sergey Senozhatsky
2018-01-17T02:24:16Z

On (01/16/18 11:19), Petr Mladek wrote:
[..]
> > [1] https://marc.info/?l=linux-mm&m=145692016122716
> > Fixes: 6b97a20d3a79 ("printk: set may_schedule for some of console_trylock() callers")
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
> > Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
>
> IMHO, this is a step in the right direction.
>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
>
> I'll wait for Steven's review and push this into printk.git.
> I'll also add your Acks for the other patches.
>
> Thanks for the patch and the various observations.

thanks!

a side note,

our console output is still largely preemptible. a typical system
acquires console_sem via console_lock() all the time, so we still
can have "where is my printk output?" cases.

for instance, my IDLE PREEMPT x86 box, has the following stats

uptime 15 min

# of console_lock() calls: 10981 // can sleep under console_sem
# of vprintk_emit() calls: 825 // cannot sleep under console_sem

-ss