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Wed, 28 Aug 2024 15:16:45 +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 mKAjAl0/z2bhTAAAD6G6ig (envelope-from ); Wed, 28 Aug 2024 15:16:45 +0000 Message-ID: Date: Wed, 28 Aug 2024 17:16:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/3] mm: add kmem_cache_create_rcu() Content-Language: en-US To: Christian Brauner , Jens Axboe , "Paul E. McKenney" , Roman Gushchin , Jann Horn , Linus Torvalds , Mike Rapoport , linux-mm@kvack.org Cc: linux-fsdevel@vger.kernel.org References: <20240828-work-kmem_cache-rcu-v3-0-5460bc1f09f6@kernel.org> <20240828-work-kmem_cache-rcu-v3-2-5460bc1f09f6@kernel.org> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: <20240828-work-kmem_cache-rcu-v3-2-5460bc1f09f6@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: mp7trk8uk94jhfncykhesqnzytidgm9e X-Rspamd-Queue-Id: 2E4D31C002C X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1724858206-106981 X-HE-Meta: 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 VJT/PXUG ALm1vXIFgoIcynyhSzLArxBZcnwZeR5GEAbf9yf3gvZVHwVVz9hZeBAAkPy5LTlRbFW0igezuUdnkYTnGuVeNxQJEMgqJb973vSEM1OsocSfLhIwDIb+Not1zaysihy6Zf1FBAUmKHfvi8FWKnhppjj+kTAQH67CObBwikaizgcaqw14VTb7cDrUPbWwohLACKccah+FS0LaxFmDVTLEIOgtseuxI4HdKi9KsSIM7u/i8drv6Mo+XTvRJHk8FwbIl88DfyrrSwxLwaEG8hv7PIMsGz5jStz6CPmFuOVWY4372Os1TmKFoJO+QZVjjOu+i/deEahH4niB0Cd+SYVIckByb+Iw7FjxBt3Lg2Mi3WbRY8JXqrRpuzqvBHSHRxpYjbeeZ4IqHPgbZNfY= 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 8/28/24 12:56, Christian Brauner wrote: > When a kmem cache is created with SLAB_TYPESAFE_BY_RCU the free pointer > must be located outside of the object because we don't know what part of > the memory can safely be overwritten as it may be needed to prevent > object recycling. > > That has the consequence that SLAB_TYPESAFE_BY_RCU may end up adding a > new cacheline. This is the case for e.g., struct file. After having it > shrunk down by 40 bytes and having it fit in three cachelines we still > have SLAB_TYPESAFE_BY_RCU adding a fourth cacheline because it needs to > accommodate the free pointer. > > Add a new kmem_cache_create_rcu() function that allows the caller to > specify an offset where the free pointer is supposed to be placed. > > Signed-off-by: Christian Brauner Reviewed-by: Vlastimil Babka Thanks.