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 20A0FEB64D9 for ; Tue, 27 Jun 2023 20:53:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231672AbjF0Uxx (ORCPT ); Tue, 27 Jun 2023 16:53:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229912AbjF0Uxp (ORCPT ); Tue, 27 Jun 2023 16:53:45 -0400 Received: from mail-oi1-x22d.google.com (mail-oi1-x22d.google.com [IPv6:2607:f8b0:4864:20::22d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58FDE19A9 for ; Tue, 27 Jun 2023 13:53:23 -0700 (PDT) Received: by mail-oi1-x22d.google.com with SMTP id 5614622812f47-3a1a47b33d8so4435820b6e.2 for ; Tue, 27 Jun 2023 13:53:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1687899202; x=1690491202; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=XFHD0hnOjuhPYILDUOJLbgwpgA6DIsDBsAhcitDEBFU=; b=AyDbzfEOwQNJQ3Q6vCBJpIzejWz0XI+CwqIDE8UgstFVF4GBN1zCUvimRHgNDXa99Q 0A2XitElZYl4vkOr9ytUm0PmYJ5QsEPCI+4zrbGGcbdnAJac6UffXXzvU8rbykoGAN78 RiYeGRGQi0rsCCIEmUY28CGLOcGd0QWkwDLQhn+j3WVmaQn0hiL1rrTM2ApFwPn3rmOW aIKz2rrQIuBq1j3yLWNWP1JGfXvLJejgPPRaYR2Sfe6YM1MfNiNFxfm4n9PGXCTAc+Ec tpgYnKyue/RmYU1Emj+1xNmzsPduOW3Zz+V1MnsoHZ24+8K57GccuEEID0ga5vyglJnq m0Uw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687899202; x=1690491202; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=XFHD0hnOjuhPYILDUOJLbgwpgA6DIsDBsAhcitDEBFU=; b=AK5ntfnEw9AyxcW7gf5YwUk/Ba28IjzvU11U0WHDoFGkEee9uy7/iVDrgc42D3JBO0 NUHEgs0bgt/oxCkOLpLPABV52Y7+TBi1+kKnzR/D7uwfh4DFJfAKEyC0srZI5XmY0SQu EqpI/TpRxg1gY4BIfE2oHIylVB3tcTB8KUZqfTtRziimiT3AuPc0UH+Di6x9v7RpjnAT pv8Q873q1AAEyC9U4IJDJdCdrJ480fbQU7Rt5/drirMbuHf4v4IY3/dUD4QuIRfn9CfH wPpDqZhTol3ZZln5wS7/3zTVCgMRcHUVQelVxRbsIdUqpna1GM2HXeAeBF7NtsCKfgjt wstg== X-Gm-Message-State: AC+VfDysAWCD2sYil0Jf55FzQ2Pt3GLjhti4kp5xUHocKWW3eDgspToD z2hjfK4qC94SnluJ0OTd2ZDHEg== X-Google-Smtp-Source: ACHHUZ4cqZstCs1nyAEh2QwWGawSrsE1fPzwiUYItaOw1DYAGKznreSljpXPuAJlmNc2pAtztzw7zA== X-Received: by 2002:a05:6808:2a47:b0:3a1:df16:2e9e with SMTP id fa7-20020a0568082a4700b003a1df162e9emr6357738oib.12.1687899202175; Tue, 27 Jun 2023 13:53:22 -0700 (PDT) Received: from ripple.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id q131-20020a817589000000b00565eb8af1fesm2009195ywc.132.2023.06.27.13.53.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jun 2023 13:53:21 -0700 (PDT) Date: Tue, 27 Jun 2023 13:53:17 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Jason Gunthorpe cc: Hugh Dickins , Andrew Morton , Gerald Schaefer , Vasily Gorbik , Mike Kravetz , Mike Rapoport , "Kirill A. Shutemov" , Matthew Wilcox , David Hildenbrand , Suren Baghdasaryan , Qi Zheng , Yang Shi , Mel Gorman , Peter Xu , Peter Zijlstra , Will Deacon , Yu Zhao , Alistair Popple , Ralph Campbell , Ira Weiny , Steven Price , SeongJae Park , Lorenzo Stoakes , Huang Ying , Naoya Horiguchi , Christophe Leroy , Zack Rusin , Axel Rasmussen , Anshuman Khandual , Pasha Tatashin , Miaohe Lin , Minchan Kim , Christoph Hellwig , Song Liu , Thomas Hellstrom , Russell King , "David Sc. Miller" , Michael Ellerman , "Aneesh Kumar K.V" , Heiko Carstens , Christian Borntraeger , Claudio Imbrenda , Alexander Gordeev , Jann Horn , Vishal Moola , Vlastimil Babka , linux-arm-kernel@lists.infradead.org, sparclinux@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 05/12] powerpc: add pte_free_defer() for pgtables sharing page In-Reply-To: Message-ID: <7b1be7d-9287-cbc6-ef7-55e44625e4e@google.com> References: <54cb04f-3762-987f-8294-91dafd8ebfb0@google.com> <5cd9f442-61da-4c3d-eca-b7f44d22aa5f@google.com> <2ad8b6cf-692a-ff89-ecc-586c20c5e07f@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 27 Jun 2023, Jason Gunthorpe wrote: > On Wed, Jun 21, 2023 at 07:36:11PM -0700, Hugh Dickins wrote: > > [PATCH v3 05/12] powerpc: add pte_free_defer() for pgtables sharing page ... > Yes, this makes sense to me, very simple.. > > I always for get these details but atomic_dec_and_test() is a release? > So the SetPageActive is guarenteed to be visible in another thread > that reaches 0? Yes, that's my understanding - so the TestClearPageActive adds more to the guarantee than is actually needed. "release": you speak the modern language, whereas I haven't advanced from olden-days barriers: atomic_dec_and_test() meets atomic_t.txt's - RMW operations that have a return value are fully ordered; which a quick skim of present-day memory-barriers.txt suggests would imply both ACQUIRE and RELEASE. Please correct me if I'm mistaken! Hugh