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b=qOrLiBszEKx/23biOQZk87zRhMJbA40mNWdnFLnvO+6ASmNShr9lvrPB+EI3DS62T kSZVlihQi0B68GKMKPm4eItVYiIhxR0DqlCmT2g3IYfQVBqd/rtv+tqpP5+t+jPE8M yZYA4wdBbqmg2Qdlt5h+t2T+Qq+zy/Olf7wXwxtq1sIktHqX3a8nkb5sPcz86WnYrr BF9v34oINbsMKvRkxwf7EPwtkvT9CHBNz3Fjuqv0FmTXyTDprtgrUyhhAr1U0Vx6gJ 33c2QO8hhrYsdMupxmk47+Kx1dS8UI5koZTpjb/6I5veUv/KKsdonu4flrgeluQDa5 uolC1xPwyoy7w== Date: Mon, 4 Nov 2024 12:49:24 +0200 From: Mike Rapoport To: Jason Gunthorpe Cc: "Gowans, James" , "quic_eberman@quicinc.com" , "kvm@vger.kernel.org" , "brauner@kernel.org" , "anthony.yznaga@oracle.com" , "steven.sistare@oracle.com" , "akpm@linux-foundation.org" , "linux-kernel@vger.kernel.org" , "seanjc@google.com" , "Durrant, Paul" , "pbonzini@redhat.com" , "linux-mm@kvack.org" , "Woodhouse, David" , "Saenz Julienne, Nicolas" , "viro@zeniv.linux.org.uk" , "Graf (AWS), Alexander" , "jack@suse.cz" , "linux-fsdevel@vger.kernel.org" Subject: Re: [PATCH 05/10] guestmemfs: add file mmap callback Message-ID: References: <20240805093245.889357-1-jgowans@amazon.com> <20240805093245.889357-6-jgowans@amazon.com> <20241029120232032-0700.eberman@hu-eberman-lv.qualcomm.com> <33a2fd519edc917d933517842cc077a19e865e3f.camel@amazon.com> <20241031160635.GA35848@ziepe.ca> <20241101134202.GB35848@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241101134202.GB35848@ziepe.ca> X-Rspam-User: X-Rspamd-Queue-Id: 56B16C0003 X-Rspamd-Server: rspam01 X-Stat-Signature: 8x3unqtwts3hutz5itr3ks1gtw8otpuo X-HE-Tag: 1730717486-783676 X-HE-Meta: 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 VRiJ4aQw svPG7JsGWtoa9rL/1VyXe5E6cbIv79qJpHQFXB5UWFXyVan0MYj2o72db03fslUAQMtTSjW5TxxjKLk/rdRHnkFDxy/6dYSgPzqyRIBRoEg9lRKC3aiSeyfMRdgXR7aJUEcBYfsgDP6B0nE5WtguxuaVqoGC3Y8NDF2ZB5ao/f4sdTtZEZVNfohqK+xSCCAvNROjgBf1WjelXzQy7DkL9R1GTpBCqo7ppXGCbupT1bG+GnnLhI70NYb21I53AV0qrw+FfuZ0vpW/XVhoMGcszUO53kO2UhdVtv7YpljDe9KmrW8M= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Nov 01, 2024 at 10:42:02AM -0300, Jason Gunthorpe wrote: > On Fri, Nov 01, 2024 at 01:01:00PM +0000, Gowans, James wrote: > > > Thanks Jason, that sounds perfect. I'll work on the next rev which will: > > - expose a filesystem which owns reserved/persistent memory, just like > > this patch. > > Is this step needed? > > If the guest memfd is already told to get 1G pages in some normal way, > why do we need a dedicated pool just for the KHO filesystem? > > Back to my suggestion, can't KHO simply freeze the guest memfd and > then extract the memory layout, and just use the normal allocator? > > Or do you have a hard requirement that only KHO allocated memory can > be preserved across kexec? KHO does not allocate memory, it gets the ranges to preserve, makes sure they are not overwritten during kexec and can be retrieved by the second kernel. For KHO it does not matter if the memory comes from a normal or a special allocator. > Jason -- Sincerely yours, Mike.