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Tue, 4 Feb 2025 10:02:47 +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 OgNFO8floWdzDQAAD6G6ig (envelope-from ); Tue, 04 Feb 2025 10:02:47 +0000 Message-ID: <4fdbb91c-df21-4dab-a165-a4e864625628@suse.cz> Date: Tue, 4 Feb 2025 11:02:47 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/4] slab, rcu: move and consolidate TINY_RCU kvfree_rcu() to SLAB Content-Language: en-US To: paulmck@kernel.org Cc: Christoph Lameter , David Rientjes , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , rcu@vger.kernel.org References: <20250203-slub-tiny-kfree_rcu-v1-0-d4428bf9a8a1@suse.cz> <5ee3321c-417a-4638-8d9e-77faa5f07462@paulmck-laptop> 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: <5ee3321c-417a-4638-8d9e-77faa5f07462@paulmck-laptop> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Rspamd-Queue-Id: 2A80FA0016 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: g17rfxqnjkqpynis9p6rrs1rfm1xw73w X-HE-Tag: 1738663369-61166 X-HE-Meta: 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 vY0GJquR sM+Ke8DE4/yRVi5YJRet1oiHJuL7tAfQDQ7h2yMM2YrNIwIElUv7+8rZ0Ig4F19MyCJWAtUrdwMtf6Vh3CSsRSW4FQKyEdSClwa5u/9CRdR5a5do6GL6mIvKnD51Unebvnqh6STvw6LqNFipgIF7MFdTo8aIydmstiWNjQy9bH+3vZvGZXfVgYrQzAWowhPNho6xj5CUZBWvdAqLWN81l3c2YHaksnlZRcSJhey7n1MSeEuhjYsR7agNv4KXEVM63E4CIxHdBBkIvDacq6b/5L9v98toy5dPgBOK1shJQECVxJjSc0EUiH+Q7LewpKe6mO28TehSsUvtvOHz95W3guXn3mzixYKyR9DNGEtYFH4PZO07MUwo1JbgUaamu2rprWC5UOa2wEcCCmdII4b3M1X6vtiFv4OF/xtNjmF9agmFcHIU= 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 2/3/25 20:07, Paul E. McKenney wrote: > On Mon, Feb 03, 2025 at 10:28:46AM +0100, Vlastimil Babka wrote: >> Following the move of the TREE_RCU batching kvfree_rcu() implementation >> to slab, we still have the simple non-batching implementation in tiny >> RCU, and RCU implementation specific ifdefs in slab code. >> >> Finish the move and integration into slab. Allow using the simple >> call_rcu() based implementation also with tree RCU when SLUB_TINY is >> enabled, as its goal is also to limit memory footprint with less concern >> for top performance. >> >> In order to avoid RCU having to recognize the fake callback function >> pointers (__is_kvfree_rcu_offset()) when handling call_rcu(), implement >> a callback that can calculate the object's address from the embedded >> rcu_head pointer without knowing the specific offset (previously SLOB >> would not have made it possible, but it's gone now). >> >> After this series, AFAIK only the following kvfree_rcu specific code >> remains in RCU: >> >> - a call to kfree_rcu_scheduler_running() from rcu_set_runtime_mode() >> >> - probably necessary and a generic registration interface would be >> unnecessary bloat? > > I am OK with this calling directly. > > Alternatively, you could create a core_initcall() that did nothing > but invoke kfree_rcu_scheduler_running(), and then drop that call from > rcu_set_runtime_mode(). Up to you guys! I was afraid there's some ordering necessary with the rest of what rcu_set_runtime_mode() does, but perhaps there's actually not. >> - declarations of kfree_rcu() API in include/linux/rcupdate.h >> >> - could be moved to slab.h after checking for/fixing up potential >> missing includes > > It would be good to move them, but no real hurry from this end. > >> git tree: >> https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux.git/log/?h=b4/slub-tiny-kfree_rcu >> >> Changes since RFC [1]: >> - Rebased to v6.14-rc1 >> - Fixed build errors reported by bots. >> - Changed where kvfree_call_rcu() is moved to in patch 1 to avoid another >> move in patch 4. >> - R-b's by Ulad and Joel >> - Fix a memory leak in kvfree_rcu_list() thanks to Ulad >> - Various comments' improvements and fixes (Joel, Ulad) >> - Rename config to CONFIG_KFREE_RCU_BATCHED (Ulad) >> >> Due to changes, didn't keep Paul's Tested-by (but thanks!) > > I re-ran the tests, so feel free to add it back in. ;-) Thanks, will do :)