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[209.85.167.52]) by smtp.gmail.com with ESMTPSA id b35sm658135lfv.82.2021.05.21.09.04.12 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 21 May 2021 09:04:13 -0700 (PDT) Received: by mail-lf1-f52.google.com with SMTP id m11so30464369lfg.3 for ; Fri, 21 May 2021 09:04:12 -0700 (PDT) X-Received: by 2002:a05:6512:36c5:: with SMTP id e5mr2652442lfs.41.1621613052578; Fri, 21 May 2021 09:04:12 -0700 (PDT) MIME-Version: 1.0 References: <20210422054323.150993-1-aneesh.kumar@linux.ibm.com> <20210422054323.150993-8-aneesh.kumar@linux.ibm.com> <2eafd7df-65fd-1e2c-90b6-d143557a1fdc@linux.ibm.com> <5ea8fa4f-a5a2-7dc4-7958-23df6a2c1f3a@linux.ibm.com> <874kewme7a.fsf@linux.ibm.com> In-Reply-To: <874kewme7a.fsf@linux.ibm.com> From: Linus Torvalds Date: Fri, 21 May 2021 06:03:56 -1000 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v5 7/9] mm/mremap: Move TLB flush outside page table lock To: "Aneesh Kumar K.V" Cc: Linux-MM , Andrew Morton , Michael Ellerman , linuxppc-dev , Kalesh Singh , Nick Piggin , Joel Fernandes , Christophe Leroy Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=GPbGcKTy; dmarc=none; spf=pass (imf22.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.167.49 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 5426AC005A01 X-Stat-Signature: oid4w1y7b5o8pebscmafydhui4pj4694 X-HE-Tag: 1621613053-619715 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: On Fri, May 21, 2021 at 3:04 AM Aneesh Kumar K.V wrote: > > We could do MOVE_PMD with something like below? A equivalent MOVE_PUD > will be costlier which makes me wonder whether we should even support that? Well, without USE_SPLIT_PTE_PTLOCKS the pud case would be trivial too. But everybody uses split pte locks in practice. I get the feeling that the rmap code might have to use pud_lock/pmd_lock. I wonder how painful that would be. Linus