Re: 4.14 backport request for dbdda842fe96f: "printk: Add console owner and waiter logic to load balance console writes"

Petr Mladek
2018-12-13T09:59:31Z

On Wed 2018-12-12 18:39:42, Daniel Wang wrote:
> > Additionally, for dbdda842fe96f to work as expected we really
> need fd5f7cde1b85d4c. Otherwise printk() can schedule under
> console_sem and console_owner, which will deactivate the "load
> balance" logic.
>
> It looks like fd5f7cde1b85d4c got into 4.14.82 that was released last month.
>
> On Wed, Dec 12, 2018 at 6:27 PM Sergey Senozhatsky
> <sergey.senozhatsky.work@gmail.com> wrote:
> >
> > On (12/12/18 16:40), Daniel Wang wrote:
> > > In case this was buried in previous messages, the commit I'd like to
> > > get backported to 4.14 is dbdda842fe96f: printk: Add console owner and
> > > waiter logic to load balance console writes. But another followup
> > > patch that fixes a bug in that patch is also required. That is
> > > c14376de3a1b: printk: Wake klogd when passing console_lock owner.
> >
> > Additionally, for dbdda842fe96f to work as expected we really
> > need fd5f7cde1b85d4c. Otherwise printk() can schedule under
> > console_sem and console_owner, which will deactivate the "load
> > balance" logic.

To make it clear. Please, make sure that the following commits are
backported together:

+ dbdda842fe96f8932ba ("printk: Add console owner and waiter
logic to load balance console writes")
+ c162d5b4338d72deed6 ("printk: Hide console waiter logic into
helpers")
+ fd5f7cde1b85d4c8e09 ("printk: Never set console_may_schedule
in console_trylock()")
+ c14376de3a1befa70d9 ("printk: Wake klogd when passing
console_lock owner")

I generated this list from git log using "Fixes:" tag. It seems
to mention all commits dicussed above.

Best Regards,
Petr