From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by kanga.kvack.org (Postfix) with ESMTP id 6514A6B0003 for ; Mon, 15 Oct 2018 18:11:46 -0400 (EDT) Received: by mail-pg1-f200.google.com with SMTP id x2-v6so15580271pgr.8 for ; Mon, 15 Oct 2018 15:11:46 -0700 (PDT) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id f8-v6si11865842pgu.370.2018.10.15.15.11.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 15 Oct 2018 15:11:45 -0700 (PDT) Date: Mon, 15 Oct 2018 15:11:43 -0700 From: Andrew Morton Subject: Re: [PATCH 1/1] mm: thp: relocate flush_cache_range() in migrate_misplaced_transhuge_page() Message-Id: <20181015151143.0d37ffe1492f5f7e51170607@linux-foundation.org> In-Reply-To: <20181015202311.7209-1-aarcange@redhat.com> References: <20181013002430.698-4-aarcange@redhat.com> <20181015202311.7209-1-aarcange@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: linux-mm@kvack.org, Aaron Tomlin , Mel Gorman , Jerome Glisse , "Kirill A. Shutemov" On Mon, 15 Oct 2018 16:23:11 -0400 Andrea Arcangeli wrote: > There should be no cache left by the time we overwrite the old > transhuge pmd with the new one. It's already too late to flush through > the virtual address because we already copied the page data to the new > physical address. > > So flush the cache before the data copy. > > Also delete the "end" variable to shutoff a "unused variable" warning > on x86 where flush_cache_range() is a noop. What will be the runtime effects of this change?