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[24.6.216.183]) by smtp.gmail.com with ESMTPSA id v1-20020a17090a0c8100b001efc46f7eaesm1844077pja.5.2022.07.13.09.49.37 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 Jul 2022 09:49:37 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.100.31\)) Subject: Re: [PATCH v1 2/5] userfaultfd: introduce access-likely mode for common operations From: Nadav Amit In-Reply-To: Date: Wed, 13 Jul 2022 09:49:35 -0700 Cc: Linux MM , Mike Kravetz , Hugh Dickins , Andrew Morton , Axel Rasmussen , David Hildenbrand , Mike Rapoport Content-Transfer-Encoding: quoted-printable Message-Id: <11B8FB03-D79F-4495-AEAE-1DED81477E12@gmail.com> References: <20220622185038.71740-1-namit@vmware.com> <20220622185038.71740-3-namit@vmware.com> <5D85870C-CBDF-45F7-A3A5-5F889521BE41@vmware.com> To: Peter Xu X-Mailer: Apple Mail (2.3696.100.31) ARC-Authentication-Results: i=1; imf08.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=p1kA2Y+H; spf=pass (imf08.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.216.44 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657730979; a=rsa-sha256; cv=none; b=Lv4u27RNMmhdwD/zT3qnX0pv10c7Ws/B12Cob0JbByNOXmGm452aIPTCCPE/tJkstC+pjI 9A6Kt3Jht8fJ4f0Ojln5x3SVBrbz8ecDU350E/Klat7kN+CAdxETDIt1V4RQgoGpwioE/x 3WGMCvBL3XJLv1/0ysxjcTazgQ/rcfg= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657730979; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=8RqRqRdRtvRryEq6CsUSfdHNV2VUEpvOZL768iAWyzM=; b=GPdG+O69SM3sFzqB+aJpCW6ZyZH4+sTj9SMDNpgZojJg1DtGaVQAlOjBO6vG7d4Mi8Il3X cFqKd72HcGAfadCwR8v5rvLfouZutcOonDe5mZCnlhvXf8Y93f1W6fPr3eVBlDor+6LlOF DpcWcDvFi5o8LM7V8QudqZrpeNSQNak= X-Rspamd-Queue-Id: 18B51160062 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=p1kA2Y+H; spf=pass (imf08.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.216.44 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 54wh3g5ti5tb4xxypcstmff8597yirxs X-HE-Tag: 1657730978-287016 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 Jul 13, 2022, at 9:02 AM, Peter Xu wrote: > On Tue, Jul 12, 2022 at 06:09:35PM -0700, Nadav Amit wrote: >> On Jul 12, 2022, at 7:56 AM, Peter Xu wrote: >=20 >=20 > What you suggested at the end sounds good to me, thanks for being > persistent. The only thing uncertain seems to be whether we need > WRITE_HINT for UFFDIO_WRITEPROTECT, all the rest sounds a good plan. Peter, thanks for the detailed feedback. I understand and agree with most of what you wrote. I think we still = have the mprotect()/UFFDIO_WRITE(un)PROTECT issue, which I either do not understand your position or disagree with it. :) Anyhow, instead of too many words, I=E2=80=99ll send v2 based on your = feedback, which would help to refine the behavior and clear any misunderstanding we might have.