netdev - Re: possible circular locking dependency detected

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Message-ID: <20160902175206.GV2356@ZenIV.linux.org.uk>
Date:   Fri, 2 Sep 2016 18:52:06 +0100
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Rainer Weikusat <rweikusat@...eradapt.com>,
        CAI Qian <caiqian@...hat.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Rainer Weikusat <rweikusat@...ileactivedefense.com>,
        Eric Sandeen <esandeen@...hat.com>,
        Network Development <netdev@...r.kernel.org>
Subject: Re: possible circular locking dependency detected

On Fri, Sep 02, 2016 at 10:12:08AM -0700, Linus Torvalds wrote:
> On Fri, Sep 2, 2016 at 10:02 AM, Al Viro <viro@...iv.linux.org.uk> wrote:
> >
> > It's very much _not_ just overlayfs being pathological - that it certainly is,
> > but the problem is much wider.
> 
> Al, can you take a look at my two patches, and see if you agree that
> they fix it, though?

AFAICS, they should.  Locking is obviously saner that way and AFAICS the
rest is absolutely straightforward.

Acked-by: Al Viro <viro@...iv.linux.org.uk>

> Of course, we now have *another* splice deadlock. That pipe inode is
> nasty, it's very easy to deadlock on it in subtle ways.

I'm still digging through iomap.c, but that's better taken to another branch
of this thread...