linux-kernel - Re: processes hung after sys_renameat, and 'missing' processes

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Message-ID: <CA+55aFwCusEdMq3_3TAXSZ=+kbN7H6AbnngVaagAZw=ZpicckQ@mail.gmail.com>
Date:	Sun, 3 Jun 2012 16:07:35 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Dave Jones <davej@...hat.com>, Al Viro <viro@...iv.linux.org.uk>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: processes hung after sys_renameat, and 'missing' processes

On Sun, Jun 3, 2012 at 3:36 PM, Dave Jones <davej@...hat.com> wrote:
>
> It's still up and in this state if you want me to gather any further info
> before I reboot it.

You seem to have lockdep enabled, since I see the lock information,
but presumably you didn't get a lockdep splat before this?

Also, sysrq-w is usually way more interesting than 't' when there are
processes stuck on a mutex.

Because yes, it looks like you have a boattload of trinity processes
stuck on an inode mutex. Looks like every single one of them is in
'lock_rename()'. It *shouldn't* be an ABBA deadlock, since lockdep
should have noticed that, but who knows.

It looks like the lock information is somewhat truncated. I suspect
the dmesg buffer had filled up with all the task data.

Can you do just "sysrq-d" for the lock information (and maybe
separately "sysrq-w" for the blocked tasks)? The non-truncated lock
data might tell us more.

               Linus
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