From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 82255D35162 for ; Wed, 1 Apr 2026 11:53:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C544D6B0005; Wed, 1 Apr 2026 07:53:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BDE066B0088; Wed, 1 Apr 2026 07:53:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AA5C56B0089; Wed, 1 Apr 2026 07:53:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 948026B0005 for ; Wed, 1 Apr 2026 07:53:50 -0400 (EDT) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 459B5E130A for ; Wed, 1 Apr 2026 11:53:50 +0000 (UTC) X-FDA: 84609827820.14.09EC6C1 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf29.hostedemail.com (Postfix) with ESMTP id BED4E12000C for ; Wed, 1 Apr 2026 11:53:48 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=nQjv+5cG; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf29.hostedemail.com: domain of harry@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=harry@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775044428; a=rsa-sha256; cv=none; b=w5dUp8j5arK4QXatWp3RsnWR++DjJNxvuY59HzRF8rH2ysrMfTd6IE6iqrnBY+h/BOIuyL IJDKR72KXhV2ejsy71JlWDZkUJ3n1V9JJHV3l5K/49t4Q3FGMqhDV+V1h9lwEXgY4cHFoR ZT9HWOyt6EEfR/0fuUhGvavL+tHYAPQ= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=nQjv+5cG; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf29.hostedemail.com: domain of harry@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=harry@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775044428; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=GADXsNFfRPgDk14ktr/Ujr7rY7o0BsOAb5pqO6oflQc=; b=c+Sm1Uo/lecCi4oSshL0o7Lhqz0YH3UO0K2+sRaofzdimOyz4cL0R6NcA6tFVb4BpNm6G6 J+XG7JDLWv/q1SusVu1OkYQy3jF4JJvCVmDKDp8G0+zlKfzbtfv6gTXYmQ4YpjxTGwIIWX z/d1sqKeDU68BK9GgkgCgICGZBnPib0= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 2E38F6013F; Wed, 1 Apr 2026 11:53:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F3C7C4CEF7; Wed, 1 Apr 2026 11:53:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775044427; bh=O/4bIPxFhYeI8VkLP9DN3SgsWmQIE648f8OII8PyyS8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nQjv+5cGYtRkn96yzMGuseLIk7H1GXT7x8/btEQ/z52u1NHxmzSoeY0e56elprOLH 9Xid3iTeGp17rC4Axo7WRWC//I8Pbvwr763q9K3tO3v+UX+wDxl4lonHSiUHVtPIcT 1HR+OUoreJJfZKe2xVLwtUHlwP8PKoezu7iZFNZ3kaAj5ZfmHIOtiKv7cEEzK8sJoc T6720uDY9cMmsAzc1yGcXmGTXMv6vk93B73Dvs/xzmAl0U1b4KBuykGkSuJYDNaREW 4rWYx1IbaqMDsguRhJQT8BsqPxvT0DGdMe7F1XdXHXPttgH3W/tJAFwLwNeeN+98o4 eUYGvmOcU432w== Date: Wed, 1 Apr 2026 20:53:45 +0900 From: "Harry Yoo (Oracle)" To: "Vlastimil Babka (SUSE)" Cc: Andrew Morton , Andrey Ryabinin , David Hildenbrand , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Muchun Song , Hao Li , Christoph Lameter , David Rientjes , Pedro Falcato , Jann Horn , Matthew Wilcox , Petr Tesarik , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, cgroups@vger.kernel.org Subject: Re: [PATCH] slab: remove the SLUB_DEBUG functionality and config option Message-ID: References: <20260401-b4-are-you-serious-v1-1-dcacda70647d@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260401-b4-are-you-serious-v1-1-dcacda70647d@kernel.org> X-Stat-Signature: y17iunww4sykpffwqgaie71mmcx3ztby X-Rspamd-Queue-Id: BED4E12000C X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1775044428-699371 X-HE-Meta: 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 wsn0+agD EijTVFPX9ucI410ubnZQT2no6k9fdODIpY8K0 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Apr 01, 2026 at 12:59:29PM +0200, Vlastimil Babka (SUSE) wrote: > The boot-time enabled per-cache debugging has served us well in the > past, but it's time for it to go, for the following reasons. **You are absolutely right!** Thank you so much for putting this together, Vlastimil! ๐Ÿ™ This is a well-structured and thoughtful proposal. Let me share my thoughts on each point below. ๐Ÿ‘‡ > - It's a debugging feature. However, thanks to the advent of LLM-based > reviews, we are not adding bugs to the kernel anymore, so it's > unnecessary now. Great point! ๐Ÿ’ฏ It's worth noting that the landscape has fundamentally shifted in recent years. I think this is a step in the right direction! โœ… > - KASAN is more powerful anyway for the classes of bugs that SLUB_DEBUG > can catch. But I suspect KASAN is likely to be removed soon too, see > above. Absolutely! ๐ŸŽฏ That said, I'd be happy to take on the follow-up work here โ€” always looking for opportunities to make my stats look shine! โ˜€๏ธ > - SLAB never had no such dynamic debugging functionality. With the > introduction of sheaves percpu caching, we have turned SLUB back into > SLAB partially, so this just follows that direction. This is a really interesting perspective! ๐Ÿค” I'd love to dive deeper into this โ€” what else could we do to continue this direction? ๐Ÿ’ก > - It's removing ~2500 lines of code and I want to keep my overal > diffstats negative. This adds a nice margin. Love this! ๐Ÿ”ฅ Less code is always better as that means less tokens โ€” better for the environment! ๐ŸŒฑ > Since the slub kunit test depends on SLUB_DEBUG, remove it too. It's not > a big loss, see the first point above. > > Singed-off-by: Vlastimil Babka (SUSE) > --- > Signed-off-by: Vlastimil Babka (SUSE) > --- I'd love to hear Sashiko (๐Ÿค–)'s thoughtsย ๐Ÿค” on this as well, but FWIW... ๐Ÿช„โœจ๐Ÿ”ฎ Acked-by: Harry Potter -- Thank you, you made my day! Harry / Hyeonggon