Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Date:   Fri, 2 Aug 2019 22:35:03 +0900
To:     Chris Wilson <chris@chris-wilson.co.uk>
Cc:     Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Subject: Re: [PATCH 2/2] i915: do not leak module ref counter
Message-ID: <20190802133503.GA18318@tigerII.localdomain>
References: <20190802123956.2450-1-sergey.senozhatsky@gmail.com>
 <20190802123956.2450-2-sergey.senozhatsky@gmail.com>
 <156475071634.6598.8668583907388398632@skylake-alporthouse-com>
 <156475141863.6598.6809215010139776043@skylake-alporthouse-com>
 <20190802131523.GB466@tigerII.localdomain>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20190802131523.GB466@tigerII.localdomain>
User-Agent: Mutt/1.12.1 (2019-06-15)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On (08/02/19 22:15), Sergey Senozhatsky wrote:
[..]
> > > Looking around, it looks like we always need to drop type after
> > > mounting. Should the
> > >         put_filesystem(type);
> > > be here instead?
> > > 
> > > Anyway, nice catch.
> > 
> > Sigh. put_filesystem() is part of fs internals. I'd be tempted to add
> 
> Good catch!
> 
> So we can switch to vfs_kern_mount(), I guess, but pass different options,
> depending on has_transparent_hugepage().

Hmm. This doesn't look exactly right. It appears that vfs_kern_mount()
has a slightly different purpose. It's for drivers which register their
own fstype and fs_context/sb callbacks. A typical usage would be

	static struct file_system_type nfsd_fs_type = {
		.owner→ →       = THIS_MODULE,
		.name→  →       = "nfsd",
		.init_fs_context = nfsd_init_fs_context,
		.kill_sb→       = nfsd_umount,
	};
	MODULE_ALIAS_FS("nfsd");

	vfs_kern_mount(&nfsd_fs_type, SB_KERNMOUNT, "nfsd", NULL);

i915 is a different beast, it just wants to mount fs and reconfigure
it, it doesn't want to be an fs. So it seems that current kern_mount()
is actually right.

Maybe we need to export put_filesystem() instead.

	-ss