From: "Michael S. Tsirkin" <mst@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org,
Maciej Sosnowski <maciej.sosnowski@intel.com>,
"David S. Miller" <davem@davemloft.net>,
stable@kernel.org
Subject: Re: [PATCH] dma: fix error handling on out of memory
Date: Thu, 14 Oct 2010 10:11:34 +0200 [thread overview]
Message-ID: <20101014081132.GA11095@redhat.com> (raw)
In-Reply-To: <AANLkTimi4vo_trVGxO9eeaYsfnRkjweG0irCGek=75Yu@mail.gmail.com>
On Wed, Oct 13, 2010 at 05:10:25PM -0700, Dan Williams wrote:
> On Mon, Oct 11, 2010 at 2:44 AM, Michael S. Tsirkin <mst@redhat.com> wrote:
> > get_user_pages might return less pages than requested. If this happens
> > for the first iovec in dma_pin_iovec_pages, then nr_iovecs is 0 and so
> > dma_unpin_iovec_pages will not unpin any pages, leaking pinned memory.
> > A similar off by one would trigger for any of the following entries.
> >
> > Fix by updating nr_iovecs and nr_pages in this case.
> >
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >
> > Error handling in dma_pin_iovec_pages still looks wrong to me. Am I
> > missing something?
>
> Still looks wrong it what way? You make sure that nr_iovecs is
> incremented so that the partial page list is freed, and we only walk
> the initialized entries in pinned_list.
In that before the patch, if get_user_pages returns less pages than
requested, we would leak pinned memory. Right?
> --
> Dan
prev parent reply other threads:[~2010-10-14 8:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-11 9:44 [PATCH] dma: fix error handling on out of memory Michael S. Tsirkin
2010-10-14 0:10 ` Dan Williams
2010-10-14 8:11 ` Michael S. Tsirkin [this message]
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