From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6185C3E8C5D; Tue, 14 Apr 2026 14:24:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776176640; cv=none; b=fh0+e5k7UsfKOBTfCsYA+Ux/Db3lEjshjgiBdtoQ9Wlu4rxZXV+R8DdB2oSrNuyrvgpcHtzV/BsZHfC/uVTKfu9dslTvwjuNOCLChGW/ohj2ALKib+yPFqBKD9WYDWDL+ZUyfBbWcJ+0BDqcp4Rj3TWBCJhfi0QxxUdiv1XHzaA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776176640; c=relaxed/simple; bh=D3Xb8PeTvLmTI+UVvNhEzjipl2DCTEFkVuBJpSK3e5A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bBnrnsTdZxJB5bo84meijjsOmuxy6NZUGQEc5Kxdnd8zcghrkuCBTJI9OKDUQQp2yL9ZmkIp9+xCeAETxpuTW+ZVaEjNXwi9+jFyYDnLAy/iN9EVIcwIffk3L88/zALug2sqhzmwMKt0FM5+oWg30Eqz9ygsqIwoUpPX2Qah/uw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ne7QX6p4; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ne7QX6p4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9FF77C2BCB0; Tue, 14 Apr 2026 14:23:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776176640; bh=D3Xb8PeTvLmTI+UVvNhEzjipl2DCTEFkVuBJpSK3e5A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ne7QX6p4nh9f/KVkal6ql22E5r/yWYe9JHa7nSlxz3j6Ic+3FzQVmlFp+3vAuTlat v0HqOSM0yhyjH6x1IQIW9w1yjn1IpsgQgDA/ke4oZiY/c7jkPkLvQfTXTCThogjp9c ZZ3+3pIh/vV6BvtlvbyB+osol2DpabaFs7qIIRZHHN4zTEmevQYfc0MyFMUA4qppiy sdM/Otrt5Eojdb4TREddxEgauSm1zgx3ntLtbVEHXfIQD7M+Bz89OCnyxFO+NHEVs6 XhYHb8/aDtAjTsZdr3Zbwz6M8YnRJuertzI2MGpRZHLYHmlPILZh/g6rUS8mxGV2eT Hh2UjFnmMz96Q== Received: from phl-compute-02.internal (phl-compute-02.internal [10.202.2.42]) by mailfauth.phl.internal (Postfix) with ESMTP id CED13F4006B; Tue, 14 Apr 2026 10:23:58 -0400 (EDT) Received: from phl-frontend-04 ([10.202.2.163]) by phl-compute-02.internal (MEProxy); Tue, 14 Apr 2026 10:23:58 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefhedrtddtgdegudefkecutefuodetggdotefrod ftvfcurfhrohhfihhlvgemucfhrghsthforghilhdpuffrtefokffrpgfnqfghnecuuegr ihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjug hrpefhvfevufffkffojghfggfgsedtkeertdertddtnecuhfhrohhmpedfmfhirhihlhcu ufhhuhhtshgvmhgruhculdfovghtrgdmfdcuoehkrghssehkvghrnhgvlhdrohhrgheqne cuggftrfgrthhtvghrnhephfdujeefvdegkefffedvkeehkeekueevfedtleehgeetlefg feevveeukefhtdetnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilh hfrhhomhepkhhirhhilhhlodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqddu ieduudeivdeiheehqddvkeeggeegjedvkedqkhgrsheppehkvghrnhgvlhdrohhrghessh hhuhhtvghmohhvrdhnrghmvgdpnhgspghrtghpthhtohepudelpdhmohguvgepshhmthhp ohhuthdprhgtphhtthhopegrkhhpmheslhhinhhugidqfhhouhhnuggrthhiohhnrdhorh hgpdhrtghpthhtohepphgvthgvrhigsehrvgguhhgrthdrtghomhdprhgtphhtthhopegu rghvihgusehkvghrnhgvlhdrohhrghdprhgtphhtthhopehljhhssehkvghrnhgvlhdroh hrghdprhgtphhtthhopehrphhptheskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepshhu rhgvnhgssehgohhoghhlvgdrtghomhdprhgtphhtthhopehvsggrsghkrgeskhgvrhhnvg hlrdhorhhgpdhrtghpthhtoheplhhirghmrdhhohiflhgvthhtsehorhgrtghlvgdrtgho mhdprhgtphhtthhopeiiihihsehnvhhiughirgdrtghomh X-ME-Proxy: Feedback-ID: i10464835:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 14 Apr 2026 10:23:58 -0400 (EDT) From: "Kiryl Shutsemau (Meta)" To: Andrew Morton Cc: Peter Xu , David Hildenbrand , Lorenzo Stoakes , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , "Liam R . Howlett" , Zi Yan , Jonathan Corbet , Shuah Khan , Sean Christopherson , Paolo Bonzini , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, "Kiryl Shutsemau (Meta)" Subject: [RFC, PATCH 01/12] userfaultfd: define UAPI constants for anonymous minor faults Date: Tue, 14 Apr 2026 15:23:35 +0100 Message-ID: <20260414142354.1465950-2-kas@kernel.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20260414142354.1465950-1-kas@kernel.org> References: <20260414142354.1465950-1-kas@kernel.org> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add UAPI definitions for userfaultfd working set tracking on anonymous memory: - UFFD_FEATURE_MINOR_ANON: minor fault support for anonymous memory - UFFD_FEATURE_MINOR_ASYNC: auto-resolve minor faults without handler - UFFDIO_DEACTIVATE: mark pages as deactivated (protnone or PTE zap) Not yet added to UFFD_API_FEATURES or UFFD_API_RANGE_IOCTLS. Signed-off-by: Kiryl Shutsemau (Meta) Assisted-by: Claude:claude-opus-4-6 --- include/uapi/linux/userfaultfd.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h index 2841e4ea8f2c..336d07e1b6de 100644 --- a/include/uapi/linux/userfaultfd.h +++ b/include/uapi/linux/userfaultfd.h @@ -79,6 +79,7 @@ #define _UFFDIO_WRITEPROTECT (0x06) #define _UFFDIO_CONTINUE (0x07) #define _UFFDIO_POISON (0x08) +#define _UFFDIO_DEACTIVATE (0x09) #define _UFFDIO_API (0x3F) /* userfaultfd ioctl ids */ @@ -103,6 +104,8 @@ struct uffdio_continue) #define UFFDIO_POISON _IOWR(UFFDIO, _UFFDIO_POISON, \ struct uffdio_poison) +#define UFFDIO_DEACTIVATE _IOR(UFFDIO, _UFFDIO_DEACTIVATE, \ + struct uffdio_range) /* read() structure */ struct uffd_msg { @@ -230,6 +233,18 @@ struct uffdio_api { * * UFFD_FEATURE_MOVE indicates that the kernel supports moving an * existing page contents from userspace. + * + * UFFD_FEATURE_MINOR_ANON indicates that minor fault interception + * is supported for anonymous private memory. Pages are made + * inaccessible via UFFDIO_DEACTIVATE (sets PROT_NONE while + * preserving the page) and faults are delivered when the pages + * are re-accessed. + * + * UFFD_FEATURE_MINOR_ASYNC indicates asynchronous minor fault + * mode. When set, faults on deactivated pages are auto-resolved + * by the kernel (PTE permissions restored immediately) without + * delivering a message to the userfaultfd handler. Use + * PAGEMAP_SCAN to find pages that were not re-accessed. */ #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0) #define UFFD_FEATURE_EVENT_FORK (1<<1) @@ -248,6 +263,8 @@ struct uffdio_api { #define UFFD_FEATURE_POISON (1<<14) #define UFFD_FEATURE_WP_ASYNC (1<<15) #define UFFD_FEATURE_MOVE (1<<16) +#define UFFD_FEATURE_MINOR_ANON (1<<17) +#define UFFD_FEATURE_MINOR_ASYNC (1<<18) __u64 features; __u64 ioctls; -- 2.51.2