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b=GhSiL6f7O/lxsNHIi3zTK1pAe0yMcZJ5vSaTqQ4A6yHzNoSf42+s/LiKyUyFigv3L YADCClytFTIOxu2FTn/4sR3XQIPpzSWdLy+ixhBq7vLs5EB5I5W30qCU4o2fIzP3cd f8Hy2aXXnc4xXyH3XAkOX1YfRDzd9pFcnPU3bGQuBeqsqmYlRDPc/d1U/8is/5DqwV vEq+EhYwnvl3pUnQTeLNmkvF1W3c2PUgCuanjh70jzRS4/fiDFDT/LdW5D+3naCDxx yLr7Yddkb0tkcg7nMW3OXDnTMwaLpq5Xc1BuGJuwhiFBlAUG6mwmhzo6bVhDuQtN+f w0hWp94pc1ybg== Date: Mon, 12 Oct 2026 15:09:31 +0100 From: Harry Yoo To: "Vlastimil Babka (SUSE)" Cc: Sang-Heon Jeon , Andrew Morton , Christoph Lameter , David Rientjes , Hao Li , linux-mm@kvack.org, Roman Gushchin Subject: Re: [PATCH v2] mm/slub: clamp slab_min_order to MAX_PAGE_ORDER Message-ID: References: <20261011014841.405327-1-ekffu200098@gmail.com> <5895ceec-df6a-4604-a7b9-8138212d786f@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5895ceec-df6a-4604-a7b9-8138212d786f@kernel.org> X-Rspamd-Queue-Id: BED9440005 X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: 3n7ncp4faz3tk79875udfb9r8wzj66q3 X-HE-Tag: 1791814174-19366 X-HE-Meta: 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 AKOp2b/f nyICgfoagkNDb0K95pkkdpXwI8Ant2JmhiJlGWA61ECHBLiH022ilo70RY/BqbE9LEMTdPrJjhYnNXgNB6eerNY+W0QXK/HHrtWbjFeg3uOX50T+qHhC9xHDnFo2oKuUOcN4mKIaupUSxvZ0rXO04wpsxMarjpI43IasVt/Za5RoGNXl3ljpdYx1osSNg5/jjuB0clk0tramDTLabwroarsBEWDKFNJADgr02wfW6LXKoIakJE4cYkv4aWyP82DWzuk4/RMoZ5qLBaGkZTjvs6l5//C5qx0t6IUVNFEvJpXMHUFTwBzUr1idl++HHJiozUHY1q4bXnfI/eyO8zUE+cVraqg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Oct 12, 2026 at 10:23:16AM +0200, Vlastimil Babka (SUSE) wrote: > On 10/11/26 03:48, Sang-Heon Jeon wrote: > > setup_slub_max_order() clamps slab_max_order to MAX_PAGE_ORDER, but > > setup_slub_min_order() has no such clamp. > > > > The buddy allocator cannot allocate more than 2^MAX_PAGE_ORDER pages > > at once, so slab_min_order above it makes no sense. > > > > If slab_min_order is set above MAX_PAGE_ORDER, it can even panic at > > boot or invoke undefined behavior in order_objects(). > > > > So clamp slab_min_order to MAX_PAGE_ORDER as well. > > > > Fixes: 81819f0fc828 ("SLUB core") > > Signed-off-by: Sang-Heon Jeon > > Hi, > > this is effectively part of my bigger refactor here: Ouch, I missed that point! > https://lore.kernel.org/linux-mm/20260923-slub_tiny_rework-v1-1-a0e66d536eb5@kernel.org/ Looking forward to seeing further updates on this ... (and hopefully do more review) -- Cheers, Harry / Hyeonggon