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 3AF5BC54EE9 for ; Wed, 7 Sep 2022 20:12:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230055AbiIGUM0 (ORCPT ); Wed, 7 Sep 2022 16:12:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229938AbiIGUMX (ORCPT ); Wed, 7 Sep 2022 16:12:23 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CEE56D9CC for ; Wed, 7 Sep 2022 13:12:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1662581542; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=PR8WUalLy9btDZgRxhhifmVZcWnjA5H+Lwe7MIcntxQ=; b=CurDqP6sVg91sxGCDy3nODFdjIEXowMKRoCLLCnCpSbY9QsFeh1Pcu/6VxbGea0domdkPl VbgCXF/QCS6wfGeCvsw8x0RzVKW57MP+639WoP7Kwx1giG87qadcB6mlHwnVR+eIHhJdhq o4prULIwoaXBUH1ABpc/NN58asVHxpU= Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-43-urpvnBA1PXKtazV2fFTjKQ-1; Wed, 07 Sep 2022 16:12:21 -0400 X-MC-Unique: urpvnBA1PXKtazV2fFTjKQ-1 Received: by mail-qk1-f199.google.com with SMTP id l15-20020a05620a28cf00b006b46997c070so12952946qkp.20 for ; Wed, 07 Sep 2022 13:12:21 -0700 (PDT) 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; bh=PR8WUalLy9btDZgRxhhifmVZcWnjA5H+Lwe7MIcntxQ=; b=J7cOzLS9oQCPjOGCdqfXjgjNTjDJQDludlTYd9WJbP3qyLk3DUtTtcGH6Wx6v/OXl9 iRD+CLD9CBOmtQt38JOFARO2x7/K6B8wCWcRvmzHlTulLgXnL+aB+resHPKovqrVcui7 oMBQj9WCEHQJvkCFuTETGNTULawSpfYasS6tOWFMoK5fNwWlafY4QLsAUUKN/kKL4ATm /fA1oj6ip8V1mGYKZbly6emmgidWAzmb0XG/kC/5A2+bae5+c+bL4TYwTGMuPpFdLz/j kV1JXCsGsg2p87STq40yz9ukqBgpG2wiGM6eYkg0BGbW+PASiT3WnFOWYGcViHA7TGVr G6AQ== X-Gm-Message-State: ACgBeo33eokRmo+6eNygdvuAQy1YNzMjj8Xmnn6/OgDD4YTBzHxF+EwU wrzG+rmLTHIt3KtnwIr36h09wQh+g5joX1HHA9Fb3odD28vm2tM+fwjAikI51ARzp69hLamn3f5 dX/XrQVaZXxQWwM3ryyHcqLVR X-Received: by 2002:a37:794:0:b0:6ba:c4c6:5772 with SMTP id 142-20020a370794000000b006bac4c65772mr3899658qkh.257.1662581540287; Wed, 07 Sep 2022 13:12:20 -0700 (PDT) X-Google-Smtp-Source: AA6agR73M0W+Epq5dj5LsV52688VKEeeZ/nLsno9QEVhJpOlqX9zO7Psv2NZ0/u62ChoHi1bpiJOoA== X-Received: by 2002:a37:794:0:b0:6ba:c4c6:5772 with SMTP id 142-20020a370794000000b006bac4c65772mr3899630qkh.257.1662581539926; Wed, 07 Sep 2022 13:12:19 -0700 (PDT) Received: from xz-m1.local (bras-base-aurron9127w-grc-35-70-27-3-10.dsl.bell.ca. [70.27.3.10]) by smtp.gmail.com with ESMTPSA id v2-20020a05620a0f0200b006bb0e5ca4bbsm16343485qkl.85.2022.09.07.13.12.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Sep 2022 13:12:18 -0700 (PDT) Date: Wed, 7 Sep 2022 16:12:16 -0400 From: Peter Xu To: Yang Shi Cc: david@redhat.com, kirill.shutemov@linux.intel.com, jhubbard@nvidia.com, jgg@nvidia.com, hughd@google.com, akpm@linux-foundation.org, aneesh.kumar@linux.ibm.com, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [v2 PATCH 2/2] powerpc/64s/radix: don't need to broadcast IPI for radix pmd collapse flush Message-ID: References: <20220907180144.555485-1-shy828301@gmail.com> <20220907180144.555485-2-shy828301@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220907180144.555485-2-shy828301@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 07, 2022 at 11:01:44AM -0700, Yang Shi wrote: > The IPI broadcast is used to serialize against fast-GUP, but fast-GUP > will move to use RCU instead of disabling local interrupts in fast-GUP. > Using an IPI is the old-styled way of serializing against fast-GUP > although it still works as expected now. > > And fast-GUP now fixed the potential race with THP collapse by checking > whether PMD is changed or not. So IPI broadcast in radix pmd collapse > flush is not necessary anymore. But it is still needed for hash TLB. > > Suggested-by: Aneesh Kumar K.V > Signed-off-by: Yang Shi Acked-by: Peter Xu -- Peter Xu