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Shutemov" To: Wei Yang Cc: akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] mm/page_vma_mapped: page table boundary is already guaranteed Message-ID: <20191128083143.kwih655snxqa2qnm@box.shutemov.name> References: <20191128010321.21730-1-richardw.yang@linux.intel.com> <20191128010321.21730-2-richardw.yang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191128010321.21730-2-richardw.yang@linux.intel.com> User-Agent: NeoMutt/20180716 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 Thu, Nov 28, 2019 at 09:03:21AM +0800, Wei Yang wrote: > The check here is to guarantee pvmw->address iteration is limited in one > page table boundary. To be specific, here the address range should be in > one PMD_SIZE. > > If my understanding is correct, this check is already done in the above > check: > > address >= __vma_address(page, vma) + PMD_SIZE > > The boundary check here seems not necessary. > > Signed-off-by: Wei Yang NAK. THP can be mapped with PTE not aligned to PMD_SIZE. Consider mremap(). > Test: > more than 48 hours kernel build test shows this code is not touched. Not an argument. I doubt mremap(2) is ever called in kernel build workload. -- Kirill A. Shutemov