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b=Wy7NQKj3fhyw22FiWKKToNQI4Z6x9WLayrVH4AboIYUcVruYvgI3GGcGVq3IQqhS1 fnkCwqUTHk/rgvNiiADE+hlhHxyXXbHv9N9d59HRWskgxPVdU1i98zDzKuyqLinoLL HzDVwlp0D4xqbtUBwnmZI6Lx0Y3B4Bop08EH8ZEWLNnJ2xPFL0tMfs16ItYVD3H9Qf oosSM5ewYZuLTicqSEaf+TI08RqxEjKHl2pXFwHO6CIWGkGiVKf8XbOO2tKzr91OOc 5SOzxxRTlQ8rldNaR5UmoXFJyKm9BJORfQ+r5JhTp370iMGxL6ICiERHP5feSeHDg7 owJRKAHIoZSMg== Date: Wed, 2 Sep 2026 12:12:50 +0100 From: Harry Yoo To: Zi Yan Cc: Vlastimil Babka , Andrew Morton , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Alan Stern , Greg Kroah-Hartman , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/slab: reject unsupported kmalloc() sizes Message-ID: References: <20260830-limit_kmalloc_size-v2-1-bf4ca9c63c88@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260830-limit_kmalloc_size-v2-1-bf4ca9c63c88@nvidia.com> X-Stat-Signature: 3jd49swj7h8rei8tw7z7rj9upfrgbi1u X-Rspamd-Queue-Id: 5551E40008 X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1788347574-931868 X-HE-Meta: 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 VoGUsGfO Bx0M7S3x4SJClnTvqgWXESgDUr0OAgBUrxK9HqxQzAAmg+WsDg+P6GRntFRdTw+ueFqCpuYSzSxCGMMbYXbPQvv2bRaf0f4AvLlLaF/Qwy3pV0u4T7x/u3uCfHV4RtJqKjIE9hQaQQpWxZlB3welj9crVw2UNiiNe4bAfMg46x/SXbxMLOG+xzNtcNIvxXljtjxattKBIGb7QTgK3QFquSPuZHIijK4XmLpjCZIWqI9p2H2i9JqQ9OQOPBWBwiSZ3AGRLOu8YqolAii60AxeMn8Mp0gMzO5P5Sj/K0I6IgV5nG8uR1lMbIbPdTGSveN2A3jE6piQS3/3yieE= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Aug 30, 2026 at 10:23:23PM -0400, Zi Yan wrote: > kmalloc() is used to allocate physically contiguous memory for kernel > allocations. For requests larger than KMALLOC_MAX_CACHE_SIZE, kmalloc() > uses the page allocator and can only support up to KMALLOC_MAX_SIZE. For > request sizes bigger than KMALLOC_MAX_SIZE, the page allocator can emit a > WARN because kmalloc() allocates an order greater than MAX_PAGE_ORDER. To > make the KMALLOC_MAX_SIZE limit more explicit instead of relying on the > page allocator check, add a KMALLOC_MAX_SIZE check inside kmalloc() to emit > a WARN and return NULL for requested sizes bigger than KMALLOC_MAX_SIZE. > Like the WARN in the page allocator and kvmalloc(), allow __GFP_NOWARN to > suppress the WARN. > > Suggested-by: "Vlastimil Babka (SUSE)" > Signed-off-by: Zi Yan > --- Looks good to me, Reviewed-by: Harry Yoo (Meta) -- Cheers, Harry / Hyeonggon