linux-kernel - Re: possible deadlock in console

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Message-ID: <20180619080812.GC405@jagdpanzerIV>
Date:   Tue, 19 Jun 2018 17:08:12 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        syzbot <syzbot+43e93968b964e369db0b@...kaller.appspotmail.com>,
        linux-kernel@...r.kernel.org, rostedt@...dmis.org,
        syzkaller-bugs@...glegroups.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-serial@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: possible deadlock in console_unlock

On (06/19/18 10:04), Petr Mladek wrote:
> > > 
> > > We could allow nesting. It is just a matter of how many bits we
> > > reserve for it in printk_context variable.
> > [..]
> > > In each case, I would like to keep the printk_safe context usage
> > > at minimum. It has its own problems caused by limited per-cpu buffers
> > > and the need to flush them.
> > 
> > May be. Every new printk_safe flavour comes with increasing memory
> > usage.
> 
> This must be a misunderstanding. My intention was to introduce
> printk_deferred() context. Where any printk() called in this
> context would behave like printk_deferred(). It does not need
> any extra buffers.

Ah, got it. Yes, this can work.

	-ss