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 X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B8F6C433B4 for ; Mon, 5 Apr 2021 13:13:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8D4A611BE for ; Mon, 5 Apr 2021 13:13:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237407AbhDENNX (ORCPT ); Mon, 5 Apr 2021 09:13:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237306AbhDENNX (ORCPT ); Mon, 5 Apr 2021 09:13:23 -0400 Received: from mail-wr1-x42d.google.com (mail-wr1-x42d.google.com [IPv6:2a00:1450:4864:20::42d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1F92C061756 for ; Mon, 5 Apr 2021 06:13:16 -0700 (PDT) Received: by mail-wr1-x42d.google.com with SMTP id e18so10891466wrt.6 for ; Mon, 05 Apr 2021 06:13:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=zFaUs2zEZY1KvMHisk5QgV+ZNlkWqv9xkMO07NNWBjY=; b=JLlQiMgCLKBfoJ5CY50t71UPj0WFOedXMyAKvkV/f2l8AQcXgCO/avA6LMGLM1Qtz/ TR6Bd/2xKIdUqr7pZH2hRlqD1hh+3BqmeXC3jnz07H2cm6rZYOFVL+xrEX0mTLl7ziTK BXZWGxQIo2MgPNfJP9+YxQBd+vh266c1o4TfI5Jfnj3awPs/bl9lsoXxRMCwEU++/zX5 032smYvvVZsP7kFD+qZHQN8MJgpuBieSdfHdLPk4Uj7zh8YsDw84jdkiByb7TJlCtDA1 Saz67F9K89KlNfO+VAgRBIGGLmaeq/gyICNkq9mVXy56FkMxkMbBxb877XYnDttf3vQ8 chhw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=zFaUs2zEZY1KvMHisk5QgV+ZNlkWqv9xkMO07NNWBjY=; b=VglU4c3GejJBXQn3Ri1sYHbBmjKapCKJorUuYsOjO3rpxVPhJxpOd6F2wzXtHcfR27 fbfHQd7amC4lamLblJlu9d9CN+/pzrssGXiJFEih2H77BTm7XO72i8vJqzTzQbmlSCfK mcpAcxDy+ax2BICXondwNitxnJzGbfhErou98gkN1L0iWSmF3ucIkAkdYAWx8bjc48tU g33MhoabLg9JWJGE8tysNhZDbb6uLWRKJ+5bB9PFgDbLIBBPdqwyfuUZYBel85Zy4WTS s+dkL52W1WkxI5zNJmrseaTxjCIswApxQKvvKeh/lP+C5p/uyWwE2h/z/0dhXh/qaaeS AXXw== X-Gm-Message-State: AOAM533ki/YvCQZnizoH3dBhiMxqmT4/1ar4Gf1y95q9iuCjy57s7Nsk bQ9Mhk54TOchcLRGvVlN4t0= X-Google-Smtp-Source: ABdhPJxZ6PhzLUg3ssyf/fZe2nNOXxK6Ryugz4RhScrD+tFxPao6/olhMtcPmT5HouBsXTrPw+HcQQ== X-Received: by 2002:a05:6000:251:: with SMTP id m17mr3161099wrz.171.1617628395600; Mon, 05 Apr 2021 06:13:15 -0700 (PDT) Received: from localhost.localdomain ([170.253.36.171]) by smtp.googlemail.com with ESMTPSA id p12sm27657929wrx.28.2021.04.05.06.13.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Apr 2021 06:13:15 -0700 (PDT) From: Alejandro Colomar To: mtk.manpages@gmail.com Cc: Peter Xu , linux-man@vger.kernel.org, Mike Rapoport , Alejandro Colomar Subject: [PATCH 2/5] userfaultfd.2: Add UFFD_FEATURE_THREAD_ID docs Date: Mon, 5 Apr 2021 15:13:05 +0200 Message-Id: <20210405131307.2892-3-alx.manpages@gmail.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210405131307.2892-1-alx.manpages@gmail.com> References: <20210405131307.2892-1-alx.manpages@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-man@vger.kernel.org From: Peter Xu UFFD_FEATURE_THREAD_ID is supported since Linux 4.14. Acked-by: Mike Rapoport Signed-off-by: Peter Xu [alx: srcfix] Signed-off-by: Alejandro Colomar --- man2/userfaultfd.2 | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2 index fa1b6514f..8245253c3 100644 --- a/man2/userfaultfd.2 +++ b/man2/userfaultfd.2 @@ -77,6 +77,13 @@ When the last file descriptor referring to a userfaultfd object is closed, all memory ranges that were registered with the object are unregistered and unread events are flushed. .\" +.PP +Since Linux 4.14, userfaultfd page fault message can selectively embed +faulting thread ID information into the fault message. +One needs to enable this feature explicitly using the +.B UFFD_FEATURE_THREAD_ID +feature bit when initializing the userfaultfd context. +By default, thread ID reporting is disabled. .SS Usage The userfaultfd mechanism is designed to allow a thread in a multithreaded program to perform user-space paging for the other threads in the process. @@ -229,6 +236,9 @@ struct uffd_msg { struct { __u64 flags; /* Flags describing fault */ __u64 address; /* Faulting address */ + union { + __u32 ptid; /* Thread ID of the fault */ + } feat; } pagefault; struct { /* Since Linux 4.11 */ @@ -358,6 +368,9 @@ otherwise it is a read fault. .\" UFFD_PAGEFAULT_FLAG_WP is not yet supported. .RE .TP +.I pagefault.feat.pid +The thread ID that triggered the page fault. +.TP .I fork.ufd The file descriptor associated with the userfault object created for the child created by -- 2.31.0