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From: Shakeel Butt To: Suren Baghdasaryan Cc: Harry Yoo , "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 Subject: Re: [PATCH] mm/slub: serve slabobj_ext array from a strictly larger kmalloc cache Message-ID: References: <62453403-954c-4cf1-8924-6d38184b0810@kernel.org> <09267187-6c85-438f-8791-4cce8d07892a@kernel.org> <68122038-e8e0-47ed-82f8-cb6a23e4658e@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Stat-Signature: p6knh675ebqp3b6i3ycuk6cby98et6rh X-Rspamd-Queue-Id: E44632000E X-Rspamd-Server: rspam06 X-HE-Tag: 1782762787-515508 X-HE-Meta: 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 EP5O7uqn Ob/qtAKFJIQ0gdbfW/tn6zyxemPn1ciEQ002cIbdHKP4l7BfwGLzCzOlj7iRAPNT0dWYc7ij6oKZzFv9Fc0g2zEKKnSdOjKOYYKs3cZTV054Lhw8oH6nW8Fg1siP5juTD5xL/ceywgX8yPJuD9OWIIL0dSM+DhKOf+CDrotqOwDAaCvbj2BsKtDwFCedXcdrHxB5YtMhdsJB3ZG5bQ90JxM3aSi7RXuV2R2KJdY5lG6tDWa/AdddarhllVgwzMsMbwgMEXJcGkQZ4TmH1WacFWrzA5vOVXtf5zT1aN5hvosrmzgCgInGh7XRRsw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. Let's keep the original one-line fix (serve the obj_exts array from a strictly larger cache, making the relation a DAG). We will NOT gate it on mem_alloc_profiling_enabled() as I floated earlier -- per Harry, is_kmalloc_normal(s) is already the right condition, and gating on profiling would miss the SLUB_TINY + __GFP_RECLAIMABLE|__GFP_ACCOUNT memcg case. So the bump stays unconditional for is_kmalloc_normal() caches. 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. thanks, Shakeel