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In-Reply-To: <20181213022703.GD4860@jagdpanzerIV>
From:   Daniel Wang <wonderfly@google.com>
Date:   Wed, 12 Dec 2018 18:39:42 -0800
Message-ID: <CAJmjG2-eoKTHtChWK0fdWfy872h5N1c-NgxBKZra1+ujutF+Fw@mail.gmail.com>
Subject: Re: 4.14 backport request for dbdda842fe96f: "printk: Add console
 owner and waiter logic to load balance console writes"
To:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc:     Sasha Levin <sashal@kernel.org>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        Petr Mladek <pmladek@suse.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>
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> 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.
>
>         -ss


-- 
Best,
Daniel

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