linux-kernel - Re: [PATCH] proc 1/6: implement support for automounts in task directories

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Message-ID: <m1skkuhaik.fsf@fess.ebiederm.org>
Date:	Mon, 30 Mar 2009 16:10:59 -0700
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	viro@...IV.linux.org.uk, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] proc 1/6: implement support for automounts in task directories

Alexey Dobriyan <adobriyan@...il.com> writes:

> I don't have a lot of opinion on this bug. I checked patchset to fix known
> reproducer, timeout is obviously taken out of air and not nice.

As for timeout.  The logic is that mark_mounts_for_expiry is just an
aging mechanism, and if something is actually in use it is not aged out.

In the general case the call to proc_shrink_automounts in
kernel/exit.c will clean up everything.  It is possible but unlikely
in practice that someone will pin a lot of process directories open
then stop pinning them, and after that point nothing will remain open,
so we close that hole.

I set timeout huge because it should never be needed in real life.

That said I'm up for taking this as a starting point and generalizing
the mechanisms in fs/namespace.c.  So I don't need a timeout at all,
but that is an orthogonal discussion.

Eric
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