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Fri, 13 Nov 2026 00:51:59 -0800 (PST) Received: from [172.22.0.2] ([50.175.87.158]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cddc186f472sm907794a12.6.2026.11.13.00.51.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Nov 2026 00:51:58 -0800 (PST) Date: Fri, 13 Nov 2026 00:51:54 -0800 From: Chris Down To: Kees Cook Cc: Vlastimil Babka , Harry Yoo , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Marco Elver , GONG Ruiqi , Jonathan Corbet , linux-mm@kvack.org, linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v2 2/6] mm/slab: Enable SLAB_FREELIST_RANDOM by default In-Reply-To: <202610302113.FB347BE5@keescook> References: <6bdc161bd869ead04b3b9a651ef6a83882ecbea3.1793253633.git.chris@chrisdown.name> <202610302113.FB347BE5@keescook> X-Mailing-List: linux-doc@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=utf-8; format=flowed Content-Disposition: inline Message-ID: <20261113005154.79ad6432034bf65c@chrisdown.name> User-Agent: Mutt/2.4.3 (cc9e3943) (2026-10-09) Hi Kees, Kees Cook writes: >Again, just like it should be. I wonder, though, don't these 2 changes >undercut the goal of making these boot-time selectable? I don't think so. The goal is to stop needing separate images for hosts with different needs. It was never to make every option switchable for its own sake. For these two, the only real argument for leaving them out was CPU cost, and with sheaves that cost doesn't show up at the system level [1]. So turning them on everywhere removes the reason to build without them at all. Anyone who still wants them off can still say n at build time. SLAB_BUCKETS and KMALLOC_PARTITION_CACHES are different. Their cost is memory, which is real and doesn't go away with sheaves, so those are the ones where a boot time switch makes sense. [1] https://lore.kernel.org/r/auITixAJMfLtfa7i@chrisdown.name Thanks for the review! Chris