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[34.145.75.25]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2edb6d7bf46sm12827355ad.31.2026.11.10.10.36.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2026 10:36:42 -0800 (PST) Date: Tue, 10 Nov 2026 18:36:39 +0000 From: Samiullah Khawaja To: Pratyush Yadav Cc: Pasha Tatashin , Mike Rapoport , Andrew Morton , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 2/2] mm/memfd_luo: keep memfd frozen until finish Message-ID: References: <20261110175855.2437084-1-pratyush@kernel.org> <20261110175855.2437084-3-pratyush@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20261110175855.2437084-3-pratyush@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261110_103644_503392_79D82ABE X-CRM114-Status: GOOD ( 11.10 ) X-Spam-Score: -17.6 (-----------------) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-23.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIMWL_WL_MED,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Nov 10, 2026 at 06:58:53PM +0100, Pratyush Yadav wrote: >From: "Pratyush Yadav (Google)" > >After a memfd is retrieved, it immediately goes back into "normal" >operation. The file comes back unfrozen, and its pages can migrate, it >can be truncated, and so on. If the memfd is depended on by something, >like iommufd, that can open a window for folios to move around before >the consumer can re-establish its references. > >Finish is the conceptual point when a retrieved file can start to behave >as "normal". So take an extra reference on the folios and freeze the >memfd on retrieve until finish. > >Suggested-by: Pasha Tatashin >Reviewed-by: Pasha Tatashin >Signed-off-by: Pratyush Yadav (Google) >--- > mm/memfd_luo.c | 87 +++++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 68 insertions(+), 19 deletions(-) > Reviewed-by: Samiullah Khawaja