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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-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: B5DB52000B X-Spam-Status: No, score=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=4.0.1 X-Stat-Signature: a3rbns1neokatyqb15ck4eumc8jj99xf X-Rspam-User: X-HE-Tag: 1794335804-655857 X-HE-Meta: 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 qBO5PKif YikfmZcbxuZag8z9bGkZ4yv7rHK19N7q8XCm3Iw5/PH70h9QtdOIU53ZLHk7igYxB8mZJMrzL0ahFGYzwD3ugd8DPD2Now5gyT6YeP59/LiL3wS7DgImW0btSCn2c45yC41GjNZ4JgD5jJjc/bluddoMcg0I6PFjoNxclylDix/JfwTNKrd8pHP6I1kPYEXKC232UzbUGGhVBRhSM0tlJOygej7WdZVehWWaTbVOHri3DGWkUj7maI+o8N0h4h50MLqLFb/cbTA+RO0+JPqYBb4H7rv6lSNI+M2S/oToosSeASLfDBprkD3+Da4AqRd1DskFwb2SqTDudQdKatBqis20X7tWTYNuyoXwqLTU8XhVLlDNMCDFYIN2UXbmBiGJphXc69pRJJdryBIYmqBzlpsQv+8Hc3vIBTqA71LIZk413n36djLsQQHE5kqpvIxRLB/DkLr6X0rU6zc9MH6J+nhDzKB57Pcyp0dYW Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: 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