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Shutemov" To: Zi Yan Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [PATCH] thp: Simplify splitting PMD mapping huge zero page Message-ID: <20200328001959.ggi74gch42soulus@box> References: <20200327170353.17734-1-kirill.shutemov@linux.intel.com> <1437F525-1510-45CD-A67F-13DF525083B4@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1437F525-1510-45CD-A67F-13DF525083B4@nvidia.com> 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, Mar 27, 2020 at 01:23:07PM -0400, Zi Yan wrote: > On 27 Mar 2020, at 13:03, Kirill A. Shutemov wrote: > > > Splitting PMD mapping huge zero page can be simplified a lot: we can > > just unmap it and fallback to PTE handling. > > So we will have an extra page fault for the first read to each subpage, > but nothing changes if the first access to a subpage is a write, right? > BTW, what is the motivation for this code simplification? Match what we do for file-THP. I found a problem with the patch. Ignore it for now. -- Kirill A. Shutemov