From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9DE9C61DA4 for ; Thu, 9 Mar 2023 09:11:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 007816B0071; Thu, 9 Mar 2023 04:11:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id ED30E6B0072; Thu, 9 Mar 2023 04:11:01 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D4C516B0075; Thu, 9 Mar 2023 04:11:01 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id C1FFB6B0071 for ; Thu, 9 Mar 2023 04:11:01 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 665C9C0680 for ; Thu, 9 Mar 2023 09:11:01 +0000 (UTC) X-FDA: 80548790322.09.D96B1E3 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf01.hostedemail.com (Postfix) with ESMTP id B87DB40010 for ; Thu, 9 Mar 2023 09:10:59 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=IIx5PMn3; spf=pass (imf01.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1678353059; a=rsa-sha256; cv=none; b=ko4vvPjbsmAgVSd+jREYDqmF0RV3R0q/uUXMtQyrZOQNcYVL3qlqLdMI4ef5yc4l7FFO0S SlF+CD2f/pQbvWJjLBY0L1j3Wyx/iVLeL0zU2JB+2snQmmdi/mgicUSn+prXic3mFJi35O Yl0KCRAjYDPWCf9oybiV9pDkT1/9QI0= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=IIx5PMn3; spf=pass (imf01.hostedemail.com: domain of rppt@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=none) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1678353059; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=57kLtPS+zFSQ7vWLzOinsR3TjaN2nLj2zeZ+o/DIWbc=; b=eai6gN1jLyCykSmx6QCuia75aKORn4ovub+5IyLRHpZBORVvRm/hkVRUmkE2lnk1Hd7H+i iEby4zVasiH0jr2N0thVg901sXtP5NM3DFg9DadQVUR5ckEq9xKZ4zUhbfZDkeDXfvssVI HMwVEOpPOgnFe/76uTj51s6LCBwfZE4= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C40C961A85; Thu, 9 Mar 2023 09:10:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9EDEC433EF; Thu, 9 Mar 2023 09:10:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1678353058; bh=JjxLR1+avtcuU4KUyJgBQZFgh1Cf7A5zbpgdMrdZvVE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IIx5PMn30TNo8a8IuyvEKukqRXpKoZayeXcBCbC0BwmnoZdX0q7qqg5BHT/oAdy7s p1L+KaEdsP3DUMY6Lv3IaMYlRG8UzjzLxgqqO2gA803JWhxbrPOX+idFSKFVX8aiYw GLDB1k9jX+JpzErr7EqylDoGxMXYZ7MlkAoX0pFpMJ9nllobadjP5TH0dOp29xkBhE T2xluqTlLlODlXyIeTsmQDsnhTOihkvryBAkeO4W9KkLEPDRZ5skU1j8S1BQUn1+C3 lq+CIRCH8cMJ5j8yya5ZA3f5yxRIyvYEdOMB9CqPaikcCnB8aik2aleoHIe+MV7j4I iwZpjc5fFsOyA== Date: Thu, 9 Mar 2023 11:10:42 +0200 From: Mike Rapoport To: Axel Rasmussen Cc: Alexander Viro , Andrew Morton , Hugh Dickins , Jan Kara , "Liam R. Howlett" , Matthew Wilcox , Mike Kravetz , Muchun Song , Nadav Amit , Peter Xu , Shuah Khan , James Houghton , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v4 4/4] mm: userfaultfd: add UFFDIO_CONTINUE_MODE_WP to install WP PTEs Message-ID: References: <20230308221932.1548827-1-axelrasmussen@google.com> <20230308221932.1548827-5-axelrasmussen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230308221932.1548827-5-axelrasmussen@google.com> X-Rspam-User: X-Rspamd-Queue-Id: B87DB40010 X-Rspamd-Server: rspam01 X-Stat-Signature: uccbsj8kjq5se9tz4j1m1wk6uxufn7aj X-HE-Tag: 1678353059-50952 X-HE-Meta: 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 3wWUtLHz UQkm/1H3+kqY5zyg/+my2ThGzyiy1D1EuN0+JbUJhxyku9ySAMGAVbggTe549RGZsczq2Dz8GHiIzJ0IrF62IrgW4kzV2suZl45gmYuMqdQ9qpRhDOtio4arX8L5x+gRdFLNYL7cHdoPbfZC+CH+cywFYduKLyRD0YPQ7wwxKrDyD1UxRRIpos0/sfYiFC7VyWYXUTFhCZcng3NTkx1E/BbKlzEnVBp9XiHjjMjVgNlQ3Yw7+uWMn49PFFf7vTT6Tv0sNW3PbkwR4rm+ijjnrz/YmtRko/Cx1bQ3Sl/Y63coceabJuxGd82EMi5He9WPJ4RNw2xKlUOu+BX+fRU0KIpht3u1D4Jc7JIaozJQcGiMUEmCkuC4tplClIFg8ivFcwwKORyIRvviGOp5CUAdUR+cVdHPM1JBeEhDV9ZinJUWlmEH+OnmzHl+nk2jAByCqJ1RGJU574JFR6SLJ+9ky0csI/w== 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 Wed, Mar 08, 2023 at 02:19:32PM -0800, Axel Rasmussen wrote: > UFFDIO_COPY already has UFFDIO_COPY_MODE_WP, so when installing a new > PTE to resolve a missing fault, one can install a write-protected one. > This is useful when using UFFDIO_REGISTER_MODE_{MISSING,WP} in > combination. > > This was motivated by testing HugeTLB HGM [1], and in particular its > interaction with userfaultfd features. Existing userfaultfd code > supports using WP and MINOR modes together (i.e. you can register an > area with both enabled), but without this CONTINUE flag the combination > is in practice unusable. > > So, add an analogous UFFDIO_CONTINUE_MODE_WP, which does the same thing > as UFFDIO_COPY_MODE_WP, but for *minor* faults. > > Update the selftest to do some very basic exercising of the new flag. > > [1]: https://patchwork.kernel.org/project/linux-mm/cover/20230218002819.1486479-1-jthoughton@google.com/ > > Acked-by: Peter Xu > Signed-off-by: Axel Rasmussen Acked-by: Mike Rapoport (IBM) > --- > fs/userfaultfd.c | 8 ++++++-- > include/linux/userfaultfd_k.h | 3 ++- > include/uapi/linux/userfaultfd.h | 7 +++++++ > mm/userfaultfd.c | 5 +++-- > tools/testing/selftests/mm/userfaultfd.c | 4 ++++ > 5 files changed, 22 insertions(+), 5 deletions(-) > > diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h > index 005e5e306266..14059a0861bf 100644 > --- a/include/uapi/linux/userfaultfd.h > +++ b/include/uapi/linux/userfaultfd.h > @@ -297,6 +297,13 @@ struct uffdio_writeprotect { > struct uffdio_continue { > struct uffdio_range range; > #define UFFDIO_CONTINUE_MODE_DONTWAKE ((__u64)1<<0) > + /* > + * UFFDIO_CONTINUE_MODE_WP will map the page write protected on > + * the fly. UFFDIO_CONTINUE_MODE_WP is available only if the > + * write protected ioctl is implemented for the range > + * according to the uffdio_register.ioctls. > + */ > +#define UFFDIO_CONTINUE_MODE_WP ((__u64)1<<1) Please add the description of the new flag to Documentation/ and to the userfaultfd man pages. > __u64 mode; > > /* -- Sincerely yours, Mike.