linux-kernel - WARNING in tty_ldisc

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Date:	Tue, 18 Oct 2011 02:36:23 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Дмитрий Матросов 
	<sgf.dma@...il.com>, Jiri Slaby <jirislaby@...il.com>
Cc:	645071@...s.debian.org, LKML <linux-kernel@...r.kernel.org>
Subject: WARNING in tty_ldisc_reinit

Дмитрий Матросов wrote:
> I try to compile with printk() instead of printk_ratelimited() in your
> patch, and it's succeeded. Then i install it with

Sorry, I didn't notice that would need to be changed.  Thanks for fixing
that yourself!

> # dpkg -i   ./linux-image-2.6.32-5-686-bigmem_2.6.32-38a~test_i386.deb
> # dpkg --configure --force-depends-version  linux-image-2.6.32-5-686-bigmem
> 
> and then try to reproduce this bug. Here is the result:
> 
> [   65.162361] apm: BIOS not found.
> [   65.276280] [drm] nouveau 0000:01:00.0: nouveau_channel_free: freeing fifo 2
> [   84.368180] tty_ldisc_reinit: refcount of  is still 2
[...]
> I suppose, that result of previous attempt is not very useful, because
> something is missed in the output (after "of" word). So, i rewrite
> your patch a little:
> [..]
> +               printk(KERN_DEBUG "%s: refcount of %p (%s, num=%d, mag=%d,
> flags=%d) is still %d\n",
> +                               __func__,
> +                               tty->ldisc->ops, tty->ldisc->ops->name, tty->ldisc->ops->num,
> tty->ldisc->ops->magic, tty->ldisc->ops->flags,
> +                               atomic_read(&tty->ldisc->users));
> [..]

"%ps" should have resulted in printing the symbol name for the structure
that the argument points to.  I don't know why that didn't work.

Anyway, Jiri, this should be the information you wanted way back in
<http://article.gmane.org/gmane.linux.kernel/1176604>:

> [   83.736104] tty_ldisc_reinit: refcount of c13c7878 (n_tty, num=0, mag=21507, flags=0) is still 2

You can find more explanation of when this happens in the bug log at
<http://bugs.debian.org/645071>.

Ben.

-- 
Ben Hutchings
No political challenge can be met by shopping. - George Monbiot

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