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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36128C4167B for ; Thu, 29 Dec 2022 17:10:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233662AbiL2RKg (ORCPT ); Thu, 29 Dec 2022 12:10:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229773AbiL2RKd (ORCPT ); Thu, 29 Dec 2022 12:10:33 -0500 Received: from mail-wm1-x333.google.com (mail-wm1-x333.google.com [IPv6:2a00:1450:4864:20::333]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34B9665FF for ; Thu, 29 Dec 2022 09:10:32 -0800 (PST) Received: by mail-wm1-x333.google.com with SMTP id p1-20020a05600c1d8100b003d8c9b191e0so13590621wms.4 for ; Thu, 29 Dec 2022 09:10:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=6iXEUQF/2BeuvNlDHuWFT5+6QZOEeSuxDVO3QVbXNvA=; b=XR0ru+oBYc3oN3vyc9Ob6/Y1TDuoxbKD2u8sKbsHcnCbPnh3aocBcj9V8LxT9OsZvT TTCg7jo7VamSs55XaIJxAuuosVqaVNcwuGuWOprI57Y9GsDtcPP7t28Y1fCXIjOTF8ki key4JyfC0WoT309l+iM+cmepJxDCKU3IGpxlMbA8KJtb3sqZKlrdvrjCG0QC3dve+yD0 zrJ0jsGVLGEKhqf9EAcE1+v7NFU5BDbHczvrIAYW9SPu1y8l3CshcjE6M5Ce2WUUSFDJ t9qPEgvMmeK/Sk9mhrHuTQNczG5/fIi6gF+hVdDsM/LcesOTwBSzN3hLbcN6+ssKu58Z BtIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=6iXEUQF/2BeuvNlDHuWFT5+6QZOEeSuxDVO3QVbXNvA=; b=7IELI/j3VCNGlaYkiDCM75ppa9dHuw5Z6i9RVgXIureKZ1oHp2NQpvh7cK9jqh+uF6 Ql8cdFQXzQHtETt9SdcEL05Bz1mqtxz6ZL8Gl3OTUnk56zefee9V2YPqBPwqZnWh1OI6 L25YhA6Ijt/CfPRs10s5T5sr4yorw79RFZ1WVn3Nbw++gL6VKEAT4NNkRVTEgs1mpaxG QNEcmAkzStHf1eWeihkbXX7I0U5xvcsOQI/7048l8cgFv/o7EDWhpd74pN4lOfyXCtUb utuYsyY99LBuQR6bhq6KiVP3cYADuk1jbl8iZ+ob7CXb/+iPCU6m/P/Ic06LMz3aey+Q Pg/Q== X-Gm-Message-State: AFqh2kpxSpYmMeYCNFmll1YsoPJF+pjeGCYGVp106lZ7QjxsrXM0iynA W8qryl5tlmVxsaRMWMRZvng= X-Google-Smtp-Source: AMrXdXvlBHWAQSqBO/YIG9QKvKgK4LB2zVDBB9SbqCS4j2rIQ3Wj1hJx3JKsZmsQeILggk9yQrXxsA== X-Received: by 2002:a05:600c:4255:b0:3d2:282a:e1f5 with SMTP id r21-20020a05600c425500b003d2282ae1f5mr20289099wmm.30.1672333830620; Thu, 29 Dec 2022 09:10:30 -0800 (PST) Received: from localhost ([2a00:23c5:dc8c:8701:fdcf:52c5:7af:c812]) by smtp.gmail.com with ESMTPSA id n14-20020a5d484e000000b00242814c2cf0sm18873420wrs.4.2022.12.29.09.10.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Dec 2022 09:10:29 -0800 (PST) Date: Thu, 29 Dec 2022 17:10:28 +0000 From: Lorenzo Stoakes To: Matthew Wilcox Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, liam.howlett@oracle.com, surenb@google.com, ldufour@linux.ibm.com, michel@lespinasse.org, vbabka@suse.cz, linux-kernel@vger.kernel.org Subject: Re: [QUESTION] about the maple tree and current status of mmap_lock scalability Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 29, 2022 at 04:51:37PM +0000, Matthew Wilcox wrote: > The mmap_lock is taken for many, many things. [snip] I am currently describing the use of this lock (for 6.0) in the book and it is striking just how broadly it's used. I'm diagramming it out for 'core' users, i.e. non-driver and non-some other things, but even constraining that leaves a HUGE number of users. I've also documented the 'unexpected' uses of the page_table_lock, which seems to have been significantly improved over time but still a few cases remain! Am happy to give you (+ anybody else on MAINTAINERS list) an early copy of the relevant bit (once I've finished the diagrams anyway) if that'd be helpful! Now if you guys could stop obsoleting my work that'd be great ;)