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Fri, 03 Jul 2026 10:26:20 -0700 (PDT) Received: from fedora ([2607:fb91:1408:4b9b:69b2:bc92:5299:1677]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-51c41d2d688sm21828511cf.17.2026.07.03.10.26.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Jul 2026 10:26:20 -0700 (PDT) Date: Fri, 3 Jul 2026 13:26:17 -0400 From: Gregory Price To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@meta.com, corbet@lwn.net, skhan@linuxfoundation.org, peterz@infradead.org, luto@kernel.org, akpm@linux-foundation.org, feng.tang@linux.alibaba.com, pmladek@suse.com, mhiramat@kernel.org, marc.herbert@linux.intel.com, joel.granados@kernel.org, lirongqing@baidu.com, kees@kernel.org, nathan@kernel.org, linusw@kernel.org, arnd@arndb.de, deller@gmx.de, jpoimboe@kernel.org, ruanjinjie@huawei.com, lukas.bulwahn@redhat.com, ryan.roberts@arm.com, ojeda@kernel.org Subject: Re: [PATCH 2/2] kernel/entry: add kernel.syscall_user_dispatch sysctl Message-ID: References: <20260627205551.769684-1-gourry@gourry.net> <20260627205551.769684-2-gourry@gourry.net> <877bncm5y7.ffs@fw13> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <877bncm5y7.ffs@fw13> > > + /* Arming can be denied at runtime via sysctl, disarming is allowed */ > > + if (mode != PR_SYS_DISPATCH_OFF && !syscall_user_dispatch_allowed) > > + return -EPERM; > > That might be similar to other sysctls, but if an application had it > enabled prior to the sysctl=off toggle, then that application will > suddenly fail in operation if it requires to move the dispatch window. > If the admin is turning it off globally, is that not exactly what the admin wants? The alternative is a hard disable that will simply result in undefined behavior (windows syscall ABI being interpreted at a linux syscall) instead of failing gracefully on the re-arm. This seemed like the better option. ~Gregory