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Fri, 09 Oct 2026 02:35:10 -0700 (PDT) From: Matt Fleming X-Google-Original-From: Matt Fleming Date: Fri, 9 Oct 2026 10:35:09 +0100 To: Joerg Roedel Cc: Suravee Suthikulpanit , Ashish Kalra , Vasant Hegde , Sairaj Kodilkar , Baoquan He , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@cloudflare.com Subject: Re: [PATCH 0/2] iommu/amd: Fix device table setup in kdump kernels Message-ID: References: <20261002133143.3628181-1-matt@readmodwrite.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261002133143.3628181-1-matt@readmodwrite.com> On Fri, Oct 02, 2026 at 02:31:41PM +0100, Matt Fleming wrote: > From: Matt Fleming > > An AMD kdump kernel booted with crashkernel=512M,high and > crashkernel=0,low fails to allocate its device table because there's no > memory below 4G. IOMMU init fails and, on our systems with an Intel > E810 NIC, the ice driver's TX queues time out, so the dump never gets > sent. > > Since commit 38e5f33ee359 ("iommu/amd: Reuse device table for kdump"), a > kdump kernel normally reuses the previous kernel's table. Patch 1 > programs the new table if reuse fails. Patch 2 drops GFP_DMA32 for > kdump kernels. Normal kernels still allocate below 4G, because that's > what the kdump kernel checks before reusing the table. > > On an AMD EPYC system with an E810 NIC, the kdump kernel without these > patches failed the order-9 GFP_DMA32 allocation and its TX queues timed > out. With these patches, the kdump kernel reused the old device table > and the dump was written over the network. > > Matt Fleming (2): > iommu/amd: Program device table when kdump reuse fails > iommu/amd: Don't allocate kdump device table from DMA32 > > drivers/iommu/amd/init.c | 23 ++++++++++++++++++++--- > 1 file changed, 20 insertions(+), 3 deletions(-) Hey Joerg, I know it was Plumbers and ksummit this week, but have you had chance to look at these two patches? Thanks, Matt