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=-23.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, 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 7EB31C433B4 for ; Sun, 18 Apr 2021 12:10:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5367A61359 for ; Sun, 18 Apr 2021 12:10:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230193AbhDRMLL (ORCPT ); Sun, 18 Apr 2021 08:11:11 -0400 Received: from smtp-fw-33001.amazon.com ([207.171.190.10]:13482 "EHLO smtp-fw-33001.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230096AbhDRMLL (ORCPT ); Sun, 18 Apr 2021 08:11:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1618747843; x=1650283843; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=Rzc2V/R201sumpOkX2o09+dzhxfF4BjiJWbV12yT7kM=; b=CykkYixooSI6hjhUmyfAGEa+Ne5NaJIQTFKADzk7ls6z4sy8IK+5hnVn aDAPFfKzvM9Yob5djligm4SAoQiGtqfKKyGL4zHz7uo4U6QPcmaOJIGn/ L7WSHQ9haqbUr1N6LzA+0zBhRVWhItLHf2f8xLuOQgn4ouGpDA4yAub4O 4=; X-IronPort-AV: E=Sophos;i="5.82,231,1613433600"; d="scan'208";a="119325745" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO email-inbound-relay-2a-69849ee2.us-west-2.amazon.com) ([10.25.36.210]) by smtp-border-fw-out-33001.sea14.amazon.com with ESMTP; 18 Apr 2021 12:10:37 +0000 Received: from EX13D13EUA001.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan2.pdx.amazon.com [10.236.137.194]) by email-inbound-relay-2a-69849ee2.us-west-2.amazon.com (Postfix) with ESMTPS id 4EB40A0405; Sun, 18 Apr 2021 12:10:36 +0000 (UTC) Received: from EX13MTAUEE002.ant.amazon.com (10.43.62.24) by EX13D13EUA001.ant.amazon.com (10.43.165.24) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sun, 18 Apr 2021 12:10:34 +0000 Received: from 8c85908914bf.ant.amazon.com.com (10.1.213.14) by mail-relay.amazon.com (10.43.62.224) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sun, 18 Apr 2021 12:10:31 +0000 From: Gal Pressman To: Jason Gunthorpe , Doug Ledford CC: , Alexander Matushevsky , Yossi Leybovich , Gal Pressman , Leon Romanovsky , Jason Gunthorpe , Peter Xu , Andrew Morton , Mike Kravetz Subject: [PATCH for-next v4] RDMA/nldev: Add copy-on-fork attribute to get sys command Date: Sun, 18 Apr 2021 15:10:25 +0300 Message-ID: <20210418121025.66849-1-galpress@amazon.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org The new attribute indicates that the kernel copies DMA pages on fork, hence libibverbs' fork support through madvise and MADV_DONTFORK is not needed. The introduced attribute is always reported as supported since the kernel has the patch that added the copy-on-fork behavior. This allows the userspace library to identify older vs newer kernel versions. Extra care should be taken when backporting this patch as it relies on the fact that the copy-on-fork patch is merged, hence no check for support is added. Don't backport this patch unless you also have the following series: 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes") and 4eae4efa2c29 ("hugetlb: do early cow when page pinned on src mm"). Fixes: 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes") Fixes: 4eae4efa2c29 ("hugetlb: do early cow when page pinned on src mm") Signed-off-by: Gal Pressman Reviewed-by: Leon Romanovsky --- PR was sent: https://github.com/linux-rdma/rdma-core/pull/975 Changelog - v3->v4: https://lore.kernel.org/linux-rdma/20210412064150.40064-1-galpress@amazon.com/ * Mention that nla_put_u8() return value is ignored on purpose v2->v3: https://lore.kernel.org/linux-rdma/21317d2c-9a8e-0dd7-3678-d2933c5053c4@amazon.com/ * Remove check if copy-on-fork attribute was provided from nldev_set_sys_set_doit() v1->v2: https://lore.kernel.org/linux-rdma/20210405114722.98904-1-galpress@amazon.com/ * Remove nla_put_u8() return value check * Add commit hashes to commit message and code comment --- drivers/infiniband/core/nldev.c | 14 ++++++++++++++ include/uapi/rdma/rdma_netlink.h | 2 ++ 2 files changed, 16 insertions(+) diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c index b8dc002a2478..6722011c6e81 100644 --- a/drivers/infiniband/core/nldev.c +++ b/drivers/infiniband/core/nldev.c @@ -146,6 +146,7 @@ static const struct nla_policy nldev_policy[RDMA_NLDEV_ATTR_MAX] = { [RDMA_NLDEV_ATTR_UVERBS_DRIVER_ID] = { .type = NLA_U32 }, [RDMA_NLDEV_NET_NS_FD] = { .type = NLA_U32 }, [RDMA_NLDEV_SYS_ATTR_NETNS_MODE] = { .type = NLA_U8 }, + [RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK] = { .type = NLA_U8 }, }; static int put_driver_name_print_type(struct sk_buff *msg, const char *name, @@ -1697,6 +1698,19 @@ static int nldev_sys_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh, nlmsg_free(msg); return err; } + + /* + * Copy-on-fork is supported. + * See commits: + * 70e806e4e645 ("mm: Do early cow for pinned pages during fork() for ptes") + * 4eae4efa2c29 ("hugetlb: do early cow when page pinned on src mm") + * for more details. Don't backport this without them. + * + * Return value ignored on purpose, assume copy-on-fork is not + * supported in case of failure. + */ + nla_put_u8(msg, RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK, 1); + nlmsg_end(msg, nlh); return rdma_nl_unicast(sock_net(skb->sk), msg, NETLINK_CB(skb).portid); } diff --git a/include/uapi/rdma/rdma_netlink.h b/include/uapi/rdma/rdma_netlink.h index d2f5b8396243..342c9db5b3c1 100644 --- a/include/uapi/rdma/rdma_netlink.h +++ b/include/uapi/rdma/rdma_netlink.h @@ -533,6 +533,8 @@ enum rdma_nldev_attr { RDMA_NLDEV_ATTR_RES_RAW, /* binary */ + RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK, /* u8 */ + /* * Always the end */ base-commit: 7d8f346504ebde71d92905e3055d40ea8f34416e -- 2.31.1