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Mon, 17 Aug 2026 22:20:26 -0700 (PDT) From: Daehyeon Ko <4ncienth@gmail.com> To: Lorenzo Stoakes Cc: Andrew Morton , Mike Rapoport , David Hildenbrand , "Liam R . Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Alexei Starovoitov , Daniel Borkmann , "David S . Miller" , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , James Bottomley , Hagen Paul Pfeifer , Pedro Falcato , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] mm/secretmem: properly account locked pages Date: Tue, 18 Aug 2026 14:20:06 +0900 Message-ID: <20260818052006.2387242-1-4ncienth@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260814-secretmem-accounting-v1-1-d2f8c677980b@kernel.org> References: <20260814-secretmem-accounting-v1-1-d2f8c677980b@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: rjwmedwqfc3isrnr4guwm6h3tbcoz54e X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 7308B20004 X-HE-Tag: 1787030428-32242 X-HE-Meta: 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 /Wx3A5hF jzgvLsBB2llBglqyQ6GSsl7uVdOUrAGJrIEwygNWW4qXiZ/VSeKlQWWOTYrDqdCrDCfAn/sRCuXppUqpH/LYLTFLIJK97eG69thezenzZPCMO9vWqQjmRfbmHOTpP0LNFUvy0Mi6n6N8Vb+5A1DVq22s+1BAEJOO+J1PWp8RD2s4pbZjBVm3E7LQZyf/kzgVTnN5gEq8isKeTLr2P4qJRyryXX9FAo9uld2A3jI3OgmrnXb50QxsCR74w7OAkLOXbTRiA5Iek29IJZjYeIl5PMgwsJDgV8yzf+VkG/IdZ/+HpydIW/ZfoHCNf7kxE32Djc7Rs8cQ40ap92hHNfIlhtk5gF95pA4gfumGD+TB8sfJryCUQDeTQcWhgvq4ubWDaK5MJhCZP24u9rsgtNZVSsFtQiDCu/r19oeEX8P7S/qr9rH9NZezm0b5qb1hSmmuYeR/9rvMi368hgNkXGX8NsUr69tNAmqlhTjrwQrB1Fe1g/bU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Thanks for the patch. I tested this v1 on its stated base with an x86_64 KASAN kernel. The supplied selftest passed 6/6 in three boots. Additional fork/unmap and inherited-VMA mremap tests also passed. One question: the inode stores the creator's user_struct, but the fault path uses the current task's RLIMIT_MEMLOCK. secretmem_init_inode_priv(): state->user = get_uid(current_user()); __secretmem_account_pages(): page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; With A limited to one page and B to four, A created the fd and passed it to B. B faulted four pages, after which A got SIGBUS faulting one page on a new fd: CROSS_PRINCIPAL receiver_pages=4 creator_fresh_page=0 This seems to charge A's locked_vm using B's limit. Is that intended? Thanks, Daehyeon