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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-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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> 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