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[142.68.128.5]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6d354178d31sm19306126d6.118.2024.11.01.06.42.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 01 Nov 2024 06:42:02 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1t6ruc-00000000SZq-12Ar; Fri, 01 Nov 2024 10:42:02 -0300 Date: Fri, 1 Nov 2024 10:42:02 -0300 From: Jason Gunthorpe To: "Gowans, James" Cc: "quic_eberman@quicinc.com" , "kvm@vger.kernel.org" , "rppt@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: <20241101134202.GB35848@ziepe.ca> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: A34E0160023 X-Stat-Signature: y13jtu385drzbscf9scifi1rxezxhjuq X-Rspam-User: X-HE-Tag: 1730468505-637217 X-HE-Meta: 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 hP6d+2nx 8JjWqN1asmhZgPpasE2dTxXYRzTJ2XrH+/sY8Ov9FrGkkdWvXcL3wN7wDfSEjltKY1ioCmrUJwIh++X86KXKm3BsJSQLGuXBPKNgh8JZwhfa2wGqZ3U8/FsrYjSGqk9539FGHHKpthTIxzE26jzIjvE0GxikRV200JbG2cFKpZwwmwM+b2GTZWgxFJJSK7pYKH4wV3vBg9GWgJpVi2jmMZ6iTxxfO9rSvGPKOvOnf/TSSSAG9Y22yVCSYslb4GtCYcE0YsdSPf/BNogABkC93ct8RNya8Ax7BV5ZAU8I7KXUNjUZMSkiyCJg7x367qr15oAjFwcD7as4V7bA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.005614, 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 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? Jason