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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 2E13A1C0010 X-Stat-Signature: jkitafzuaqucjg6mc6435jskb8zkbyhm X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1780431283-777985 X-HE-Meta: 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 kGad5kzP VsELnXArB3cNyRfEo31FHNDvSVmpHaUWGf/2oNBZGY3N7ZoSJbNLBWSY1ygY518eN1qa5iBHQ4Fzg+8gXzNvwzlsme9Iz4Eae8jBY73m5qsOf8fP2vyf3aYxfU1puH+wmrQwRqB5xcc1MM1G/RdTnJOjYGGlRGhEivapUKp2K0zSdWlVi/nw6y7fZSyfiWLPZPb/R9vemFFcLEvpNF9MGBH/YLDssuokukA2mPVuD04QpXzqnBkOhVyBUOvZ1ebopf5Z5g9oa0mNsHXBttU30l61l+MiO+H4Ig6Af7AtA9DpXjScHS4SGfFk6MSo3s+A5AgwjeV42uxR7q3n6NT7vjCVD17xYJmxNvLDFSvknX5sdreU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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