From: Jason Gunthorpe <jgg@nvidia.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com>,
Albert Ou <aou@eecs.berkeley.edu>,
asahi@lists.linux.dev,
Baolin Wang <baolin.wang@linux.alibaba.com>,
iommu@lists.linux.dev, Janne Grunau <j@jannau.net>,
Jernej Skrabec <jernej.skrabec@gmail.com>,
Joerg Roedel <joro@8bytes.org>,
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linux-arm-kernel@lists.infradead.org,
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Joerg Roedel <joerg.roedel@amd.com>,
Jon Hunter <jonathanh@nvidia.com>,
patches@lists.linux.dev, Samiullah Khawaja <skhawaja@google.com>,
stable@vger.kernel.org, Vasant Hegde <vasant.hegde@amd.com>
Subject: Re: [PATCH] iommu: Always fill in gather when unmapping
Date: Thu, 2 Apr 2026 19:51:21 -0300 [thread overview]
Message-ID: <20260402225121.GI310919@nvidia.com> (raw)
In-Reply-To: <ec51ef14-e360-43a6-ae62-44a939ec8027@arm.com>
On Thu, Apr 02, 2026 at 07:11:13PM +0100, Robin Murphy wrote:
> > > @@ -2714,6 +2714,10 @@ static size_t __iommu_unmap(struct iommu_domain *domain,
> > > pr_debug("unmapped: iova 0x%lx size 0x%zx\n",
> > > iova, unmapped_page);
> > > + /* If the driver itself isn't using the gather, mark it used */
> > > + if (iotlb_gather->end <= iotlb_gather->start)
> > > + iommu_iotlb_gather_add_range(&iotlb_gather, iova, unmapped_page);
> >
> > The gathers can be joined across unmaps and now we are inviting subtly
> > ill-formed gathers as only the first unmap will get included.
> > We do have error cases where the gather is legitimately empty, and
> > this would squash that, it probably needs to check unmapped_page for 0
> > too, at least.
>
> Maybe try looking at the rest of the code around these lines...
Okay, well lets do this one, do you want to send it since it is your
idea?
Jason
prev parent reply other threads:[~2026-04-02 22:51 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-31 19:56 [PATCH] iommu: Always fill in gather when unmapping Jason Gunthorpe
2026-04-01 10:40 ` Jon Hunter
2026-04-01 11:23 ` Pranjal Shrivastava
2026-04-01 12:58 ` Jason Gunthorpe
2026-04-01 16:33 ` Robin Murphy
2026-04-01 17:36 ` Jason Gunthorpe
2026-04-02 18:11 ` Robin Murphy
2026-04-02 22:51 ` Jason Gunthorpe [this message]
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