From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.227.196 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794559920; b=JxjqEuWnTwmf8EMb8Gj018uizDAnJvuC6YIadi9tnXUXSpUC754dCzGQg8xs6Ncc5U6S k0JzG2mIlVH/6T/J5oKFQo1iDEcTrYuTMDNkxVuT0ou2yfvxUW+LHQiSeT0kbTvif/YG0 CGchxoyTfv4VLpeRIJw3zIGyiiqLmA1fqNFPhPagYjUrwrlaZeOTYvPl8Z67pPikV0r54 csBZkG0c9vS59fqxmzHV2Mo37Ke+L9bOC2E38NZ9E8JW8NrbYnpKdfsSEr7sLHcOLzbD0 YFR3tCRbRIryHiF7tA3F5Rz/T6dQgpYuzGSIlFOaJXRd4/DQzs55HkCLPk16HLXLqcw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794559920; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Date:From:To:Cc:Subject:In-Reply-To:References:MIME-Version: Content-Type:Content-Disposition:Message-ID:User-Agent; bh=d8ixB8K8R172rrdk/LmhJTXU2lsskw0hIUmehvKI8Xk=; b=j0m2uu+jQULGP1O+/Fk6HK9a/YIy98laiLjxWWeNpGmfasR21zJnpLlKVmYBFJD+GSe/ CBV7w7UOx3RLTaeW2gAT2sbXut0ByqZp1hxGVvV03HmCWiygYwNHHVX8VrXk5+5u2RkJC MUaNwxBTexN5U9CF2ujJfGfaE4ZksTkoVtQX0Fg14FcVhhUUYpezLzkiQeuBOJ0an+7As QJmXEy8wuW8zO0fJ91cWyP0WRozO8Qzc9FwZEMG9xyxFZNtZINDwIqL26j6SCaqaklbFb Pj8TiuCRrdc02stIT0XBjQbjXaY3Pi+egZ7z3swWGVQ50WU7iQj7IQsG3mL4Qi0gK1Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=chrisdown.name; spf=pass smtp.mailfrom=chrisdown.name; dkim=pass header.d=chrisdown.name header.i=@chrisdown.name header.a=rsa-sha256 header.s=google header.b=wo3tKroa; arc=none smtp.remote-ip=74.125.227.196 Received: from mail-pi2-f4.google.com (mail-pi2-f4.google.com [74.125.227.196]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 12E31606A33F for ; Fri, 13 Nov 2026 08:51:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 12E31606A33F Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=chrisdown.name Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chrisdown.name Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chrisdown.name header.i=@chrisdown.name header.a=rsa-sha256 header.s=google header.b=wo3tKroa Received: by mail-pi2-f4.google.com with SMTP id 41be03b00d2f7-cdd8c1fdf4aso209256a12.1 for ; Fri, 13 Nov 2026 00:51:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chrisdown.name; s=google; t=1794559919; x=1795164719; darn=vger.kernel.org; h=user-agent:message-id:content-disposition:content-type:mime-version :references:in-reply-to:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=d8ixB8K8R172rrdk/LmhJTXU2lsskw0hIUmehvKI8Xk=; b=wo3tKroanTXQku0Q5OnfqMKYq9yZNuO+X2W6SNK/K+KqSIfeJq373T/eDUMzD8F+qW OTb5E8QNC8pMyltEE9uat7XEZhHW3BimWbhRUIriZmN9YvErn51CndJIq1p4y/4bQBll TE99QnuUYAnr6Qc5BzQga+/sZqg5s55Lntf3o= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794559919; x=1795164719; h=user-agent:message-id:content-disposition:content-type:mime-version :references:in-reply-to:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=d8ixB8K8R172rrdk/LmhJTXU2lsskw0hIUmehvKI8Xk=; b=0KKASeBGnbcR6B9g6whNWgOulZYudNcI3GF48yADZH4T9TDB8EVjyhwTmywzUo/yjp zshyUNHzKYrBMBCGnimYuumi/KJ4+6Z1XCWJWbGxKv/IxB/4LPYHK76Mo2nv98Bgl/8T 1/wKt/amL9UQeAu/55uYTIO5WffklQeTahwdosPoJunDiK1ORKGjrBDVfExopBHU5Eju zr5dmHWaV1WngWk93R2EqGj8NQEAHtIvIhF+WDAkTiG4Pnlw59j/+ScwmVWjMBaytHLy uIgCo+7jxW0MlZknEpf3oHPXiVlHXWlQeMF8yCJs6Hqaprkmc+fl23/aI650ohArlDQz /Qcg== X-Forwarded-Encrypted: i=1; AL+hErHm/QHNIOzOWMB6WNBvLftbMmUVA6RC/KrWd/JdNT3jP+VIxTq5GEywb7hUtz+WVrlMRkv1H1kYGPKMPqQ=@vger.kernel.org X-Gm-Message-State: APuU4Z8pjTZDN+CHm/JFsygM3zH0EbZxEI7bbIv9EMtD5UEDwarfYKHT 2FmE4xTvwgmWWjKxm+W4eKQzp4+imB8wwUVp+slM5QK68KG2vd39wj4OYF6VJFl2Ey4= X-Gm-Gg: AYBFou3CDxO018LOOafW2pTcUpCBuVymle21FYdJ7yehD/6xdTejifuDfCE8yUMCY36 QmvGRDaVKr0fcRkz+C4r8d8KfbNwgPt9FwnkQLgXq5tmzqux3KFRcvjnvloZFEIrK31vV2Aj6zA PALdGU+qU6p33E0a9/YkOX7ZFpVjU+UoQRrvXRBRh7hEOYaxkctOcG6B/taCABe9K8dmW+t0gJ0 /FjarCeYUuGhnkgEPAcbPgUXdUmiQjsIv+XWw6fLXxg4eKtrMhwcbIB9o4VUUAOf4fbrSCJwmyq tSY9illJhPw/UnyRTjq2iuq+RoIg+rPG2Q6UuJCTOprzCmdub/gLX0qsD/09ano03owjV2i6zNs 5dfql/m3ijABmlEH+nP/15ZBDyliYYsDOWk+n2698NKlsJe403gPINjp09lcmkcDEK4FZGYb+9k yQXiTDTB7KFsnDqGy0G2zp3FWaBmkUg2lDFOFYpH/lhtha2AqVadwVz//zUfVomoMJVnJKXe9PF dhZd75X9ODIUvKeZlpvPS/QP8ofU0I/9Pn1B6Hm5tiJ1U0GexZzfFvFhsO0vd2WbMUpO/SlWEln Q8nMoOyfpbCJfuy7LjNrhYw7AgL9CEkcDwUtmFRieSBFFuxJX4DclCveFqHzotisIpJq3bVUeVu ey2t37GlVMsMjAfmTzdA79LoQ+qZVrl7+Pn7ZBCak2o0dJ8AwBcMz3c8RO7e0XjrQ12k4asI30V 0ylMBDTeaNxRSDqWoF/PLUfKohgNYeSnN80lvjTd03tXmA5lTCNvcZPoP+q2c= X-Received: by 2002:a05:6a21:798f:b0:3e2:1a24:fb85 with SMTP id adf61e73a8af0-3f7a4dbd84bmr1333192637.1.1794559919456; 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-kernel@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