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Howlett" , maple-tree@lists.infradead.org, linux-mm@kvack.org Subject: Re: [PATCH] maple_tree: use KMEM_CACHE to create maple_node caches Message-ID: References: <20241104061617.450907-1-sunke@kylinos.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 63EA4180006 X-Stat-Signature: cmxpu4uytokupze8zgx69ekfycusd8et X-HE-Tag: 1730780262-888528 X-HE-Meta: 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 VS8fvNIf Cup2MADaOaRl371Grb+U2+WRZ61U7Oo6vQna2ZV8R6pxxSvMT7V0ddmhX9nrmH+fLNAuFYHMxspZwbXIOrZqQekURH+nzoU1VlzeXIn/DEQiebTcjdTkmPYIsKk4JKNGZm8+PrZGd3Wqp68FjbjW/5+UO82byTCtoTj3SM+AqEa2woXBRTkyKYcGwg1y5JAPUYKpiIznhfHBLzbLjxnCcSXg7HzS8MrPbmhm7knMOBWqQmMBVTfgB1l+MFxbSLrwUHUNs/CYLhgYk4oO7RhmLPwtOsw== 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 Tue, Nov 05, 2024 at 10:21:00AM +0800, Ke Sun wrote: > > its size (eg 256 bytes) as the bottom bits of pointers to nodes are used > > for other purposes. KMEM_CACHE() does not give us this guarantee. > > The code comments of kmem_cache say: 'The alignment of the struct > determines object alignment.' > #define KMEM_CACHE(__struct, __flags) \ > __kmem_cache_create_args(#__struct, sizeof(struct __struct), \ > &(struct kmem_cache_args) { \ > .align = __alignof__(struct __struct), \ > }, (__flags)) You're looking right at your bug, and you don't see it.