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[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 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 In-Reply-To: <20220907180144.555485-2-shy828301@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: david@redhat.com, jhubbard@nvidia.com, hughd@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jgg@nvidia.com, aneesh.kumar@linux.ibm.com, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, kirill.shutemov@linux.intel.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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