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Fri, 04 Dec 2020 12:21:56 -0800 (PST) Date: Fri, 4 Dec 2020 15:21:55 -0500 From: Peter Xu To: Andrea Arcangeli Cc: Hugh Dickins , Matthew Wilcox , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Mike Rapoport , David Hildenbrand Subject: Re: [PATCH v2] mm: Don't fault around userfaultfd-registered regions on reads Message-ID: <20201204202155.GQ108496@xz-x1> References: <20201202234117.GD108496@xz-x1> <20201203180234.GJ108496@xz-x1> <20201204023051.GL108496@xz-x1> <20201204192329.GP108496@xz-x1> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline 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, Dec 04, 2020 at 02:37:17PM -0500, Andrea Arcangeli wrote: > If we use _UFFD_SWP_UFFD_WP it looks much cleaner to keep it in the > pte, not in the swp entry, since then you can use the already existing > methods that only can take in input the pte_t (not the swp_entry_t). Ah, I see now. Yes it looks nicer if we don't even need swp_entry_t knowledge to recognize the special pte. So I'll try all these ideas and update. Thanks, -- Peter Xu