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Fri, 13 Jun 2025 09:04:34 -0700 (PDT) Date: Fri, 13 Jun 2025 09:04:34 -0700 (PDT) From: "Christoph Lameter (Ampere)" To: Harry Yoo cc: Vlastimil Babka , David Rientjes , Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Shakeel Butt , Muchun Song , Suren Baghdasaryan , Kent Overstreet , Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , linux-mm@kvack.org Subject: Re: [RFC PATCH] mm/slab: save memory by allocating slabobj_ext array from leftover In-Reply-To: <20250613063336.5833-1-harry.yoo@oracle.com> Message-ID: <00e91300-c6e6-5330-f514-4628ae2ba696@gentwo.org> References: <20250613063336.5833-1-harry.yoo@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Server: rspam01 X-Stat-Signature: 89e41qxpjp1r9i4cy9txmi98e1q66mnq X-Rspamd-Queue-Id: D6F5E160011 X-Rspam-User: X-HE-Tag: 1749831200-968081 X-HE-Meta: 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 FrBN9Nh7 c3a3E47cTjaeOH0gaMgDhzrsNONAIRur1hSaU+RWe2JfyikYL+xiMK5P869hXbDLqPuQJikJfKsjpTgN4nCRiByjV56xnocjtXu7QCBIBzjXAyOyAaKRWIL4mIcQ/tnB0Wn5IDXj0SiZ+SxcH2wH8cjB6/Z7eH3Wkg4VWKNSKhBiW5H7+r8e7cA2a5c87xQ5pnqIDjK2Mox8Oe6nP2lfX5X+u530Hl4urrEJhcY4McwnH2uhb6uPjV88FULInDqNaVbdPOY/isUT3LcongizfJSAywJoCURAzEWZUcL5d5EudveJpZdm/SPGQAcAzc9w3YvF3kgWty5IFJgiXuq+plxfE16oFbk7g19v3eCJ50SndzXmvCOqGRmg9bw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 13 Jun 2025, Harry Yoo wrote: > Allocate slabobj_exts array from this unused space instead of using > kcalloc(), when it is large enough. How does slab debug work in this case? The object layout gets a bit complicated with other metadata there as well.