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[34.140.140.54]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-475ddad455fsm123107015e9.2.2025.10.29.07.21.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Oct 2025 07:21:22 -0700 (PDT) Date: Wed, 29 Oct 2025 14:21:19 +0000 From: Mostafa Saleh To: =?iso-8859-1?Q?J=F6rg_R=F6del?= Cc: linux-mm@kvack.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, corbet@lwn.net, will@kernel.org, robin.murphy@arm.com, akpm@linux-foundation.org, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org Subject: Re: [RFC PATCH 1/4] drivers/iommu: Add page_ext for IOMMU_DEBUG_PAGEALLOC Message-ID: References: <20251003173229.1533640-1-smostafa@google.com> <20251003173229.1533640-2-smostafa@google.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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Oct 27, 2025 at 12:42:09PM +0100, Jörg Rödel wrote: > On Fri, Oct 03, 2025 at 05:32:26PM +0000, Mostafa Saleh wrote: > > +config IOMMU_DEBUG_PAGEALLOC > > + bool "Debug page memory allocations against IOMMU" > > + depends on DEBUG_PAGEALLOC && IOMMU_API && PAGE_EXTENSION > > + help > > + This config checks when a page is freed by the kernel > > + it's not mapped in any IOMMU domain. It can help with > > + debugging use-after-free from driver doing DMA. > > + This santaizer can have false-negative cases where some > > + problems won't be detected. > > + Expect overhead when enabling this + enabling the kernel > > + command line iommu.debug_pagealloc. > > + > > + If unsure, say N here. > > Expected indentation here is and not . My bad, I will fix it in v2. > > > --- /dev/null > > +++ b/drivers/iommu/iommu-debug.c > > Is there a plan for this file to contain more than page-alloc debugging? If > not, it should get a more specific name, like iommu-debug-pagealloc.c or > similar. I have no solid plans for other features, but I was hoping to build on top of that in the future, but for now we can make it “iommu-debug-pagealloc.c” Thanks, Mostafa >