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[34.145.75.25]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c85df0a63b3sm90737a12.21.2026.06.02.13.14.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Jun 2026 13:14:41 -0700 (PDT) Date: Tue, 2 Jun 2026 20:14:37 +0000 From: Samiullah Khawaja To: Will Deacon Cc: Marek Szyprowski , Jason Gunthorpe , Pasha Tatashin , Mike Rapoport , Pratyush Yadav , Alexander Graf , Robin Murphy , Kevin Tian , iommu@lists.linux.dev, kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Matlack , Andrew Morton , Pranjal Shrivastava , Vipin Sharma Subject: Re: [RFC PATCH 3/4] dma-direct: Add API to preserve/restore allocations Message-ID: References: <20260505002737.2213734-1-skhawaja@google.com> <20260505002737.2213734-4-skhawaja@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: On Mon, Jun 01, 2026 at 01:35:16PM +0100, Will Deacon wrote: >On Tue, May 05, 2026 at 12:27:36AM +0000, Samiullah Khawaja wrote: >> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c >> index ec887f443741..c2b98f91900a 100644 >> --- a/kernel/dma/direct.c >> +++ b/kernel/dma/direct.c >> @@ -6,6 +6,8 @@ >> */ >> #include /* for max_pfn */ >> #include >> +#include >> +#include >> #include >> #include >> #include >> @@ -307,6 +309,167 @@ void *dma_direct_alloc(struct device *dev, size_t size, >> return NULL; >> } >> >> +#ifdef CONFIG_DMA_LIVEUPDATE >> +int dma_direct_preserve_allocation(struct device *dev, void *cpu_addr, >> + size_t size, dma_addr_t dma_handle, >> + unsigned long attrs, u64 *state) >> +{ >> + struct dma_alloc_ser *ser; >> + int ret; >> + >> + if (!kho_is_enabled()) >> + return -EOPNOTSUPP; >> + >> + if (IS_ENABLED(CONFIG_DMA_CMA)) >> + return -EOPNOTSUPP; > >Hmm, it seems a bit overkill to do this just because CMA is compiled >in, especially as it's user-selectable in kconfig. > >Maybe you need to iterate over the CMA areas using cma_for_each_area(), >similarly to how you do with the pools? Agreed. So basically return error if the range belongs to one of the CMAs. I will update this. > >Will