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Date:   Thu, 13 Dec 2018 10:59:31 +0100
From:   Petr Mladek <pmladek@suse.com>
To:     Daniel Wang <wonderfly@google.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Sasha Levin <sashal@kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>, stable@vger.kernel.org,
        Alexander.Levin@microsoft.com,
        Andrew Morton <akpm@linux-foundation.org>,
        byungchul.park@lge.com, dave.hansen@intel.com, hannes@cmpxchg.org,
        jack@suse.cz, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Mel Gorman <mgorman@suse.de>, mhocko@kernel.org, pavel@ucw.cz,
        penguin-kernel@i-love.sakura.ne.jp,
        Peter Zijlstra <peterz@infradead.org>, tj@kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>, vbabka@suse.cz,
        Cong Wang <xiyou.wangcong@gmail.com>,
        Peter Feiner <pfeiner@google.com>
Subject: Re: 4.14 backport request for dbdda842fe96f: "printk: Add console
 owner and waiter logic to load balance console writes"
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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