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Howlett" , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Shuah Khan , Alexei Starovoitov , Daniel Borkmann , "David S . Miller" , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend , Stanislav Fomichev , James Bottomley , Hagen Paul Pfeifer , 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 v2] mm/secretmem: properly account locked pages Date: Wed, 26 Aug 2026 10:39:48 +0900 Message-ID: <20260826013948.1325213-1-4ncienth@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260822-secretmem-accounting-v2-1-fe445a7c6eb1@kernel.org> References: <20260822-secretmem-accounting-v2-1-fe445a7c6eb1@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Lorenzo, I tested the exact v2 from this Message-ID on its stated base with an x86_64 KASAN kernel. The supplied memfd_secret selftest passed 6/6 in three boots, and my accounting-boundary suite also passed in three boots. I saw no patch-attributable KASAN report, warning, Oops, or panic. A v1/v2 differential also confirms that v2 fixes the CAP_IPC_LOCK creator delegation issue Mike identified: v1: CAP_DELEGATION creator_cap_ipc_lock=1 receiver_uid=2001 receiver_pages=2 v2: CAP_DELEGATION creator_cap_ipc_lock=1 receiver_uid=2001 receiver_pages=1 I have one policy question before adding Tested-by. With a one-page soft and hard RLIMIT_MEMLOCK, a non-root task whose only effective and permitted capability was CAP_IPC_LOCK produced this on v2: CAP_ONLY uid=2002 cap_ipc_lock=1 mlock_two_pages=1 faulted_pages=1 raise_hard_rc=-1 raise_hard_errno=1 Thus ordinary mlock() of two pages succeeded, while only one secretmem page could be faulted. Raising the hard limit failed with EPERM because that requires CAP_SYS_RESOURCE. Is this divergence from ordinary mlock() the intended consequence of removing the CAP_IPC_LOCK exemption for secretmem? I saw the planned selftest split and cleanup in the follow-up discussion. I will retest the revised patch before adding Tested-by. Thanks, Daehyeon