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Subject: Re: [RFC PATCH] iommu/amd: fix a race in fetch_pte()
From:   Qian Cai <cai@lca.pw>
In-Reply-To: <20200418183429.GH21900@8bytes.org>
Date:   Sun, 19 Apr 2020 22:07:19 -0400
Cc:     iommu@lists.linux-foundation.org,
        LKML <linux-kernel@vger.kernel.org>
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Message-Id: <3733C20F-46C0-4C4F-9E37-94D361377D51@lca.pw>
References: <20200418121022.GA6113@8bytes.org>
 <57CBF6B2-4745-4E36-9AA5-7E0876E3DA8F@lca.pw>
 <20200418183429.GH21900@8bytes.org>
To:     Joerg Roedel <joro@8bytes.org>
Sender: linux-kernel-owner@vger.kernel.org
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> On Apr 18, 2020, at 2:34 PM, Joerg Roedel <joro@8bytes.org> wrote:
>=20
> On Sat, Apr 18, 2020 at 09:01:35AM -0400, Qian Cai wrote:
>> Hard to tell without testing further. I=E2=80=99ll leave that =
optimization in
>> the future, and focus on fixing those races first.
>=20
> Yeah right, we should fix the existing races first before introducing
> new ones ;)
>=20
> Btw, THANKS A LOT for tracking down all these race condition bugs, I =
am
> not even remotely able to trigger them with the hardware I have =
around.
>=20
> I did some hacking and the attached diff shows how I think this race
> condition needs to be fixed. I boot-tested this fix on-top of =
v5.7-rc1,
> but did no further testing. Can you test it please?

Sure, give it a few days to see if it could survive.=