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Thu, 29 Jan 2026 09:35:16 -0800 (PST) Received: from snaipe-arista.aristanetworks.com ([81.255.216.45]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-435e131cf16sm16904163f8f.22.2026.01.29.09.35.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Jan 2026 09:35:15 -0800 (PST) From: Snaipe To: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Subject: [RFC PATCH 0/1] Bind-mounting memfds Date: Thu, 29 Jan 2026 18:35:14 +0100 Message-ID: <20260129173515.1649305-1-me@snai.pe> X-Mailer: git-send-email 2.52.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 0CFEE1A000B X-Rspamd-Server: rspam07 X-Stat-Signature: rdncgx9eubm789czqxnqeunkfw197ctt X-HE-Tag: 1769708117-108878 X-HE-Meta: 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 VqGu93mO xyiWqc5qoC9JMl9l7GSNg3zgvMVKczLYalvH/3WQ1/NR5UqdSgAL2oHYyt/Mtme6xHqf9D//jebjYhIhpfIzdEzaHRW6J9V8s/wD17hb4kVK7nSBUS6q6IemGVxrTLpZyUV8HMGqB5Gg+6xPs0aIbt4bMLs/qF9EA5yoXXgNKo5RubdBzKe1PkE/3RDZwQVtNLZqkhxTcBipLApZoBLN06lImRitpvNk84s7f X-Bogosity: Ham, tests=bogofilter, spamicity=0.000672, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: "Franklin \"Snaipe\" Mathieu" Hi folks, I'm sending this patch that allows the use of open_tree on a memfd with the intent of bind-mounting it. I am unsure about the execution of this patch. shm_mnt fails the is_mounted check, but unlike pidfs and nsfs I can't compare the dentry's d_op against a known dentry ops global. I opted for a simple check of path->mnt against shm_mnt but I'm not sure it's the best approach. Please advise if there's anything better, otherwise, the patch itself should be straigtforward enough. Franklin "Snaipe" Mathieu (1): fs,ns: allow copying of shm_mnt mount trees fs/namespace.c | 8 ++++++++ mm/internal.h | 2 ++ mm/shmem.c | 2 +- 3 files changed, 11 insertions(+), 1 deletion(-) -- 2.52.0