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Thu, 20 Jun 2024 20:43:39 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 90qPMXuUdGbnVQAAD6G6ig (envelope-from ); Thu, 20 Jun 2024 20:43:39 +0000 Message-ID: <1917c5a5-62af-4017-8cd0-80446d9f35d3@suse.cz> Date: Thu, 20 Jun 2024 22:43:39 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 4/6] mm/slab: Introduce kmem_buckets_create() and family Content-Language: en-US To: Kees Cook Cc: "GONG, Ruiqi" , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , jvoisin , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Xiu Jianfeng , Suren Baghdasaryan , Kent Overstreet , Jann Horn , Matteo Rizzo , Thomas Graf , Herbert Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org, netdev@vger.kernel.org, rust-for-linux@vger.kernel.org References: <20240619192131.do.115-kees@kernel.org> <20240619193357.1333772-4-kees@kernel.org> <202406201147.8152CECFF@keescook> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: CB8D0C001B X-Stat-Signature: zm7xu6wcgzwusyod1mekspd149u3nzxs X-Rspam-User: X-HE-Tag: 1718916221-134405 X-HE-Meta: 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 81bGndv3 jWGIw+zBgBKnidLfvJ4OxHR+rVnvowYL5Q6s9tgWz+nHN0g0KpE4e+pCUAdYlthNrjiBOYTm08enE28qRMwtI9IDJXguZDGZ3GRy87dkcZjr+8nx9IZS2vn4Q8VXxVjt9v5E1+tbkhp38CpcKnzFhgECTu5nC7ni4ciBlA8JpPhTQWHnUr6fTd+7ZnGn3Y2D5IE7XG9YdJjakrZwLo5E3ASEqMzjPNeZyUWnd5SzUJVNXZmlDWCHPXFKydfjr8dQMyG1KsmnTkI4TVxYpSawm8OsIzRugUSDGoIH5Il07ZHzMbKZciTQlE3yDpRyckus3RY5aTGHcdLtEFW7DNUn908dKz2TcB+GTc1fb7b+Su8V6JIVFETzVhLTrPME7I+HS8eAJ 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 6/20/24 8:54 PM, Kees Cook wrote: > On Thu, Jun 20, 2024 at 03:56:27PM +0200, Vlastimil Babka wrote: >> > @@ -549,6 +549,11 @@ void *kmem_cache_alloc_lru_noprof(struct kmem_cache *s, struct list_lru *lru, >> > >> > void kmem_cache_free(struct kmem_cache *s, void *objp); >> > >> > +kmem_buckets *kmem_buckets_create(const char *name, unsigned int align, >> > + slab_flags_t flags, >> > + unsigned int useroffset, unsigned int usersize, >> > + void (*ctor)(void *)); >> >> I'd drop the ctor, I can't imagine how it would be used with variable-sized >> allocations. > > I've kept it because for "kmalloc wrapper" APIs, e.g. devm_kmalloc(), > there is some "housekeeping" that gets done explicitly right now that I > think would be better served by using a ctor in the future. These APIs > are variable-sized, but have a fixed size header, so they have a > "minimum size" that the ctor can still operate on, etc. > >> Probably also "align" doesn't make much sense since we're just >> copying the kmalloc cache sizes and its implicit alignment of any >> power-of-two allocations. > > Yeah, that's probably true. I kept it since I wanted to mirror > kmem_cache_create() to make this API more familiar looking. Rust people were asking about kmalloc alignment (but I forgot the details) so maybe this could be useful for them? CC rust-for-linux. >> I don't think any current kmalloc user would >> suddenly need either of those as you convert it to buckets, and definitely >> not any user converted automatically by the code tagging. > > Right, it's not needed for either the explicit users nor the future > automatic users. But since these arguments are available internally, > there seems to be future utility, it's not fast path, and it made things > feel like the existing API, I'd kind of like to keep it. > > But all that said, if you really don't want it, then sure I can drop > those arguments. Adding them back in the future shouldn't be too > much churn. I guess we can keep it then.