From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7DCB5C54731 for ; Tue, 27 Aug 2024 20:15:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 96C406B0082; Tue, 27 Aug 2024 16:15:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 91C806B0083; Tue, 27 Aug 2024 16:15:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 76F416B0085; Tue, 27 Aug 2024 16:15:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 55FC16B0082 for ; Tue, 27 Aug 2024 16:15:38 -0400 (EDT) Received: from smtpin19.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 9AB9C80BC6 for ; Tue, 27 Aug 2024 20:15:37 +0000 (UTC) X-FDA: 82499130714.19.3724773 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) by imf03.hostedemail.com (Postfix) with ESMTP id BED592000C for ; Tue, 27 Aug 2024 20:15:34 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=vYi3HUMv; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=b0Cz1XsW; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=vYi3HUMv; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=b0Cz1XsW; spf=pass (imf03.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1724789647; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=knGWaxH0R4m4TuW4TvM6nfIpA71Qplb2bUBb1bkN+fM=; b=MpZ2w8Lf/rPVIsn02ZkKQZarLdsUCXLi6hUYy4tkFyZwYbHqB2U3BGqyAYeXT8kFZ0NGh6 SjU8FhFfevt1somdaAohawVcua5Llg1NtKxv6F6YkhOj8MN94v/X9cTXwhDwbb4Fh/bAk7 O1+09ZuvWlXaQPvnlydsdfj2D2v4fSA= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1724789647; a=rsa-sha256; cv=none; b=m55wfRl/cdVw7WMMYrW5BHoEU9uOt/3l865tJ8r4pRL1fQ1TUy01RyH+sFu6NW0O+d3xa1 /7s34GEA1xfe5HEZ5Msbo+6icLTFf7WQXBYVECZOhyjpWRnlVFGYStB3QXz75vXmd4i+Iu rBQo+mjQ9yY7FgBj2StyKEDHZqvgWPA= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=vYi3HUMv; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=b0Cz1XsW; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=vYi3HUMv; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=b0Cz1XsW; spf=pass (imf03.hostedemail.com: domain of vbabka@suse.cz designates 195.135.223.131 as permitted sender) smtp.mailfrom=vbabka@suse.cz; dmarc=none Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id CB8A91FB8B; Tue, 27 Aug 2024 20:15:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1724789732; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=knGWaxH0R4m4TuW4TvM6nfIpA71Qplb2bUBb1bkN+fM=; b=vYi3HUMvibdq7PAKrKGB19OXblhVQ3UO+nax9hTPh+f9zWiL5ZqG7FRVnjDfyOtCuAHDFD wdYAiILks64A1y8UaVGuqkOfyYP8kvjl8kQGZfmxQ6Imz8YQ0vh69KDyiRWf9Nk7bJU9uo Dkfn1b04o6VjA8j8lNuQktR6dP00Ouc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1724789732; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=knGWaxH0R4m4TuW4TvM6nfIpA71Qplb2bUBb1bkN+fM=; b=b0Cz1XsWgroKjYdyQLGZ5bR0mOCkMcnPdP0pO3UbN++fNSPyqB/VMmbciAJs1lKO4k2Zyh 8qSDy8fqLn/kJIDg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1724789732; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=knGWaxH0R4m4TuW4TvM6nfIpA71Qplb2bUBb1bkN+fM=; b=vYi3HUMvibdq7PAKrKGB19OXblhVQ3UO+nax9hTPh+f9zWiL5ZqG7FRVnjDfyOtCuAHDFD wdYAiILks64A1y8UaVGuqkOfyYP8kvjl8kQGZfmxQ6Imz8YQ0vh69KDyiRWf9Nk7bJU9uo Dkfn1b04o6VjA8j8lNuQktR6dP00Ouc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1724789732; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=knGWaxH0R4m4TuW4TvM6nfIpA71Qplb2bUBb1bkN+fM=; b=b0Cz1XsWgroKjYdyQLGZ5bR0mOCkMcnPdP0pO3UbN++fNSPyqB/VMmbciAJs1lKO4k2Zyh 8qSDy8fqLn/kJIDg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id B490413A20; Tue, 27 Aug 2024 20:15:32 +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 vFq9K+Qzzma+fAAAD6G6ig (envelope-from ); Tue, 27 Aug 2024 20:15:32 +0000 Message-ID: <96dd4a75-e83f-4807-b43e-bd5552f6aa6d@suse.cz> Date: Tue, 27 Aug 2024 22:15:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/3] fs,mm: add kmem_cache_create_rcu() Content-Language: en-US To: Christian Brauner , Jens Axboe , "Paul E. McKenney" , Roman Gushchin , Jann Horn , Linus Torvalds , linux-mm@kvack.org Cc: linux-fsdevel@vger.kernel.org References: <20240827-work-kmem_cache-rcu-v2-0-7bc9c90d5eef@kernel.org> <20240827-lehrjahr-bezichtigen-ecb2da63d900@brauner> 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: <20240827-lehrjahr-bezichtigen-ecb2da63d900@brauner> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Action: no action X-Stat-Signature: rjac43u8awod65qthso7o4emtinb53x9 X-Rspamd-Queue-Id: BED592000C X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1724789734-63786 X-HE-Meta: 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 8mCPCSpX eesM8rAQKlLMOVmqgRW40lFhvrkF9HvFz+Rba62SW/bD8sAsN7nL91YEiO1RCuKDWfXBOOqUt/18sD8AcvNd5MVdBRpn+NTfoFd1fq8tdCzPWCYQ20HW8rzdVIGHcvLN5cauCza47uJhjrcMYtTEiTgc9IAAw+7rUffQfVh0vVrZYF2pjK3Bl9a0zHvMWCkYTb9Lbt5XycnuaXcG7WLVPsaHLVbcfOVBdpiqtU4dRFvubEdHiIRb4m2QUXOrjk8z21IxInI1xNaU4oFZMViqF1cVGhNE+dAaeSG9gpb0x0qZTMgWJhc1MqtAgp7zZsF8KR1QOIivxzimlYC4= 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 8/27/24 18:05, Christian Brauner wrote: > On Tue, Aug 27, 2024 at 05:59:41PM GMT, 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 >> accomodate the free pointer and is hardware cacheline aligned. >> >> I tried to find ways to rectify this as struct file is pretty much >> everywhere and having it use less memory is a good thing. So here's a >> proposal. >> >> I was hoping to get something to this effect into v6.12. >> >> If we really want to switch to a struct to pass kmem_cache parameters I >> can do the preparatory patch to convert all kmem_cache_create() and >> kmem_cache_create_usercopy() callers to use a struct for initialization >> of course. I can do this as a preparatory work or as follow-up work to >> this series. Thoughts? > > So one thing I can do is to add: > > struct kmem_cache_args { > .freeptr_offset, > .useroffset, > .flags, > .name, > }; Hm basically everyone uses name, size and some flags, so how about we leave those as direct parameters and args is for the rest, and in most cases would be NULL. > accompanied by: > > int kmem_create_cache(struct kmem_cache_args *args); I think we can't reuse the name with different parameters as long the old one exists? > and then switch both the filp cache and Jens' io_kiocb cache over to use > these two helpers. Then we can convert other callers one by one. > > @Vlastimil, @Jens, @Linus what do you think? In the other thread you said it's best to leave such refactoring to maintainers and I agree and don't ask you to do the cleanup in order to get what you need (and we don't need to rush it either).