From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 068C24F5E0 for ; Tue, 30 Jun 2026 02:03:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782784996; cv=none; b=suwvoqmkG4KIns9yUJxiIptlpIlUS5mBFABsHmg/zp4YKX7gM+ZFAFJhJNFkUZYFR5MwPHRgHlaH470K3hymlRsKCItjpM/bJhPJDf5cbninagbnG1reBlOLhhNjgatvmMaagEFncK3EDfreV7uxQvB8/ev8c+EU/9Z2LEZS3Ek= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782784996; c=relaxed/simple; bh=gIlD5Rr9nUSqwMntxUKTCIAi9YHW72YMlY2jAr4dOU8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=b0AFKIsmzKYRs7vuVJSq/U4QDU9AXYmFgrfP24+y0MuwQr0i4eIZTCptTrJ/a4t+jBRteguscaCV6y82IdzbsueQzxytIOTYUmbM5kWdPwGvnxP7jxahPrzhqY3XOOVtHWREtgnu2ySTTv2iFzko16/3q53qq1Untl7c2dykIxI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JB67cFz1; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JB67cFz1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C18461F000E9; Tue, 30 Jun 2026 02:03:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782784995; bh=Mh7wOyZn2mNMutLQV04yehx/G0sNH7B0Hew764ZGcLo=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=JB67cFz1Eh2BdtYGo48IZqLlyadmM5XzhgRACvMfyawWgPNoYxUHyrZy5U9qvgJWi JDCxVqtXhhj/3rGgcWOlYxodxD/oGy9i/fHg6legClp2Ygb7fjhz+l84Ecz0/Sc3MX dvocMWlQ3yLz6SWHtuNDCH9d7zateJBMlxyccULPWLKp0unyu5DGjtsY7kDyk9Fx8Q ql36xS8xTsif8z3MUyDP9o5J3ClXX31dGr2CYylHkVO8n3V1jRSpCfLNhIntXt3TLY HHTzBoPCTak0Ohj39z4YgccsnA/nZpskQIWEHaxCb/4C/cVG2Pq//iUkYMoazNaRX1 MEe4aRGsAkfqA== Message-ID: <393141e3-589d-46d0-90a6-88b9129ae67e@kernel.org> Date: Tue, 30 Jun 2026 11:03:11 +0900 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/slub: serve slabobj_ext array from a strictly larger kmalloc cache To: Shakeel Butt , Suren Baghdasaryan Cc: "Vlastimil Babka (SUSE)" , Andrew Morton , Roman Gushchin , Hao Li , Christoph Lameter , David Rientjes , Usama Arif , Meta kernel team , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Danielle Costantino , Kees Cook References: <62453403-954c-4cf1-8924-6d38184b0810@kernel.org> <09267187-6c85-438f-8791-4cce8d07892a@kernel.org> <68122038-e8e0-47ed-82f8-cb6a23e4658e@kernel.org> Content-Language: en-US From: Harry Yoo In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 6/30/26 4:52 AM, Shakeel Butt wrote: > On Sun, Jun 28, 2026 at 09:28:51PM -0700, Suren Baghdasaryan wrote: >> On Sun, Jun 28, 2026 at 8:57 PM Harry Yoo wrote: >>> >>> > > [...] > > Thanks all for great discussion. Let me summarize the conclusion and please > correct me if I missed something. I think you didn't miss anything. > Let's keep the original one-line fix (serve the obj_exts array from a > strictly larger cache, making the relation a DAG). Right. > We will NOT gate it on> mem_alloc_profiling_enabled() as I floated earlier Right. > -- per Harry, is_kmalloc_normal(s) is already the right condition, Right. > and gating on> profiling would miss the SLUB_TINY + __GFP_RECLAIMABLE|__GFP_ACCOUNT memcg > case. Right. > So the bump stays unconditional for is_kmalloc_normal() caches. Right. > This over-allocates the array for larger caches, but only for profiling and > SLUB_TINY+MEMCG users (the latter unrealistic). Acceptable for a small, > backportable fix. Yes. Thanks! -- Cheers, Harry / Hyeonggon