Re: hangs on boot in 9984d7394618df9

From: Nathan Zimmer <nzimmer@sgi.com>
To: Doug Anderson <dianders@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	Stephen Warren <swarren@wwwdotorg.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	David Woodhouse <dwmw2@infradead.org>,
	stable@vger.kernel.org,
	"linux-next@vger.kernel.org" <linux-next@vger.kernel.org>
Subject: Re: hangs on boot in 9984d7394618df9
Date: Tue, 9 Apr 2013 12:12:34 -0500	[thread overview]
Message-ID: <51644C02.7020508@sgi.com> (raw)
In-Reply-To: <CAD=FV=VrOh+3ucJ_4DfzpbMsOOWLK7rPue1e23=oV9tH-wUVPQ@mail.gmail.com>

On 04/08/2013 06:46 PM, Doug Anderson wrote:
> Al,
>
> On Mon, Apr 8, 2013 at 4:06 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
>> Folks, see if vfs.git#experimental works for you; the PITA had apparently
>> been caused by change of open() semantics for /proc/<pid>/fd/<some_pipe> -
>> it started to behave like a FIFO, i.e. wait for peer to show up.  Normally
>> that's not a problem, but if you have closed e.g. the write end of a pipe
>> and try to open /proc/<pid>/fd/<read_end_of_pipe>, you'll get open() waiting
>> for writers to appear.  Which isn't what we used to do here (open succeeded
>> immediately) and apparently that was enough to trip drakut.
>>
>> Branch head should be at 574179469f7370aadb9cbac1ceca7c3723c17bee.
> That branch booted fine for me and didn't show any problems.
>
> I wasn't easily able to merge onto linux-next and test there though.
> I tried applying these the 4 top commits of your branch to
> "next-20130408" and it didn't solve my problems.  A full merge of your
> branch to linux-next showed conflicts and I didn't dig.
>
> -Doug
I booted great for me too.
Also the numbers from the scaling test are improved also, at least on my 
128p box.
I'll verify on a 512 or larger box when I have the chance.
However I think I still should to provide some relief for the older kernels.