linux-kernel - Re: [PATCH 4/6] nouveau: unlock mmap_sem on all errors from nouveau_range

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Message-ID: <20190723172335.GA2846@lst.de>
Date:   Tue, 23 Jul 2019 19:23:35 +0200
From:   Christoph Hellwig <hch@....de>
To:     Jason Gunthorpe <jgg@...pe.ca>
Cc:     Christoph Hellwig <hch@....de>,
        Jérôme Glisse <jglisse@...hat.com>,
        Ben Skeggs <bskeggs@...hat.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/6] nouveau: unlock mmap_sem on all errors from
 nouveau_range_fault

On Tue, Jul 23, 2019 at 02:17:31PM -0300, Jason Gunthorpe wrote:
> That reminds me, this code is also leaking hmm_range_unregister() in
> the success path, right?

No, that is done by hmm_vma_range_done / nouveau_range_done for the
success path.

> 
> I think the right way to structure this is to move the goto again and
> related into the nouveau_range_fault() so the whole retry algorithm is
> sensibly self contained.

Then we'd take svmm->mutex inside the helper and let the caller
unlock that.  Either way it is a bit of a mess, and I'd rather prefer
if someone has the hardware would do a grand rewrite of this path
eventually.  Alternatively if no one signs up to mainain this code
we should eventually drop it given the staging status.