From: Baolu Lu <baolu.lu@linux.intel.com>
To: Jason Gunthorpe <jgg@nvidia.com>,
iommu@lists.linux.dev, Joerg Roedel <joro@8bytes.org>,
Robin Murphy <robin.murphy@arm.com>,
Will Deacon <will@kernel.org>
Cc: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>,
Janusz Krzysztofik <janusz.krzysztofik@linux.intel.com>,
Joerg Roedel <joerg.roedel@amd.com>,
Kevin Tian <kevin.tian@intel.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
patches@lists.linux.dev, Samiullah Khawaja <skhawaja@google.com>,
stable@vger.kernel.org
Subject: Re: [PATCH rc 2/2] iommupt: Fix short gather if the unmap goes into a large mapping
Date: Wed, 4 Mar 2026 15:20:05 +0800 [thread overview]
Message-ID: <bf7ba077-ecc0-4ff5-918d-c724b96bb0f6@linux.intel.com> (raw)
In-Reply-To: <2-v1-13a02eb0e031+a5-iommu_gather_jgg@nvidia.com>
On 3/3/26 06:22, Jason Gunthorpe wrote:
> unmap has the odd behavior that it can unmap more than requested if the
> ending point lands within the middle of a large or contiguous IOPTE.
>
> In this case the gather should flush everything unmapped which can be
> larger than what was requested to be unmapped. The gather was only
> flushing the range requested to be unmapped, not extending to the extra
> range, resulting in a short invalidation if the caller hits this special
> condition.
>
> This was found by the new invalidation/gather test I am adding in
> preparation for ARMv8. Claude deduced the root cause.
>
> As far as I remember nothing relies on unmapping a large entry, so this is
> likely not a triggerable bug.
>
> Cc:stable@vger.kernel.org
> Fixes: 7c53f4238aa8 ("iommupt: Add unmap_pages op")
> Signed-off-by: Jason Gunthorpe<jgg@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
prev parent reply other threads:[~2026-03-04 7:20 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-02 22:22 [PATCH rc 0/2] Fix two bugs in iommu gather processing Jason Gunthorpe
2026-03-02 22:22 ` [PATCH rc 1/2] iommu: Do not call drivers for empty gathers Jason Gunthorpe
2026-03-03 9:08 ` Vasant Hegde
2026-03-03 12:53 ` Robin Murphy
2026-03-03 13:04 ` Jason Gunthorpe
2026-03-03 15:56 ` Robin Murphy
2026-03-19 10:02 ` Janusz Krzysztofik
2026-03-03 18:30 ` Samiullah Khawaja
2026-03-04 7:19 ` Baolu Lu
2026-03-31 17:12 ` Jon Hunter
2026-03-31 19:58 ` Jason Gunthorpe
2026-03-02 22:22 ` [PATCH rc 2/2] iommupt: Fix short gather if the unmap goes into a large mapping Jason Gunthorpe
2026-03-03 9:08 ` Vasant Hegde
2026-03-03 18:30 ` Samiullah Khawaja
2026-03-04 7:20 ` Baolu Lu [this message]
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