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t=1792742660; bh=IdLhW5v/uXp4ejNif40TjF7Cr8YlsY2rrfu5zrwCz7c=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=DLvHS0z3aZq5esQJCFYVnmr4BZd8HRgdUe7FpM8c/zwhoNvsqtTxGjMcmiUJ954iy 4/qivbqF8g3/ACcZlqnn7TNf7fVKzzyHmS80beVWwifppBXCr41RqxdOUVP0yvmsK4 z5dMIazWDzhhA6GBnOLndxrdRIbVWdl0R8wsiexT4ZvZYWXKiQNSOpnYySqtCl722M 2S1zVy7NeBI/Hlvcq6cT0Adjjwv2wnEW8/Tvwor0Cn8lYHtACdwi35eIJ+bwbjnrJ9 70xMSu1I8xSLZlTqeVgfBxKDJxrNtSZotA+PsWNANM9e7IrLI8p53uqS2R+a6A2QUM K7oqvPGi0nEqQ== Message-ID: Date: Fri, 23 Oct 2026 10:04:16 +0200 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 2/8] mm, slab: introduce slab_debug=N Content-Language: en-US To: Harry Yoo Cc: Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Geert Uytterhoeven , Conor Dooley , Damien Le Moal , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kees Cook References: <20260923-slub_tiny_rework-v1-0-a0e66d536eb5@kernel.org> <20260923-slub_tiny_rework-v1-2-a0e66d536eb5@kernel.org> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: 67721160005 X-Stat-Signature: h74atwh3fysfop9rjx7prdgjyfym1abk X-Rspamd-Server: rspam01 X-Spam-Status: No, score=-7.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1792742661-836172 X-HE-Meta: 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 N964aMkR 1ZgoRyzGytgl9KlBg/JcRoYG0mLaTI4zTGz90jMevleA2SeBDMoJfZ9s+YG1mlMoUjrJUcwEOLUXrsNFyKSHsldC2zeIBMfrjatQR6wn4uj3NbjUcFsGiQMSPlkNEkxx6iO20bRvDL0/ij5RSEwIpWuzvpOUCHHcTgBzWNqAnmsXRF9qYhZeLvKokHL0jOr09Z8unY4ms9c3BpBCKQr/Yvy9gSaSfhJ8ntbWlv5dhe1T/9FRJ4e3zxobWY343IfFjKD0yH/EP8kfcF3yg9E+YUF9NvQPlK606SeHZxdWQwp6x/z+fkkrObQmTKA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 9/24/26 16:48, Harry Yoo wrote: > On Wed, Sep 23, 2026 at 05:45:07PM +0200, Vlastimil Babka (SUSE) wrote: >> Enabling slab_debug has the side-effect of disabling all percpu caching >> of objects (now via sheaves), which can be sometimes useful for saving >> memory for e.g. kdump kernels. To make this possible without the >> overhead (CPU or memory) of actual debugging options such as poisoning, >> introduce a No-op debug option that only forces the debugging slow paths >> and zero sheaf capacity. > > Just to clarify, the intended behavior of slab_debug=- still > does not change, right? (the name "No-op" could be confusing here I > guess) Yeah it doesn't change. Perhaps, later in the series I should consider what exactly slab_tiny=1 slab_debug=- shhould do. Hm. > And My LLM flagged an issue here (that I reviewed) > > Implementing it as debug flag has a few side effects: > > - pointer hashing will be disabled unless hash_pointers=always is > specified. [+Cc: Kees] Hm that likely should not happen with =N, will adjust. > - Disable slab merging. Since this does not affect object metadata > layout, this could be excluded. Right, also we want merging with slab_tiny=1. Thanks!