linux-kernel - Re: [PATCH 1/3] iommu: match the original algorithm

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Date:   Thu, 28 Nov 2019 11:30:20 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     John Garry <john.garry@...wei.com>
Cc:     iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] iommu: match the original algorithm

On Wed, Nov 27, 2019 at 10:01 AM John Garry <john.garry@...wei.com> wrote:
>
> On 21/11/2019 00:13, Cong Wang wrote:
> > The IOVA cache algorithm implemented in IOMMU code does not
> > exactly match the original algorithm described in the paper.
> >
> > Particularly, it doesn't need to free the loaded empty magazine
> > when trying to put it back to global depot.
> >
> > This patch makes it exactly match the original algorithm.
> >
>
> I haven't gone into the details, but this patch alone is giving this:
>
> root@(none)$ [  123.857024] kmemleak: 8 new suspected memory leaks (see
> /sys/kernel/debug/kmemleak)

Ah, thanks for catching it! I see what I missed, I should pre-allocate those
empty entries in order to make it work correctly.

I didn't catch this because this was tested on a production machine where
we can't afford CONFIG_DEBUG_KMEMLEAK=y for obvious performance
concerns.

Anyway, I will fix this and send v2.

Thanks!