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=-21.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 7FEA8C433ED for ; Mon, 12 Apr 2021 07:52:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 486066135C for ; Mon, 12 Apr 2021 07:52:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237129AbhDLHwU (ORCPT ); Mon, 12 Apr 2021 03:52:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:50338 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237110AbhDLHwT (ORCPT ); Mon, 12 Apr 2021 03:52:19 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5549E6135A; Mon, 12 Apr 2021 07:52:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618213922; bh=b6caykMxiAq91PMve97bmZcXOnTtbI521lJxug83BD0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=N9kF2HgmJqyH3wBfJZCe0kB56HDll4Qahf/AfoZjU6AM2eiBwOiUvXeC6gQu7STKQ tI3mxfCzswwx1TXLaqgt4oeBvLhrDjfy4bzJHARa7zxDu6rsYVNLGj57yQFiRWONEq ZJ40ZBP/YR1NF6cGzmxMIi+Z+5amDPQIQWK+IKXQfLemAF4wouZ+GrhawNwIBQLl6d rG7gnodiOOF3jE8LJVCcqYChkRdUSfyXOSrIN6ZmrKG6XnRmpXv85LcgABrl0D1Qz9 5g/mRJSuT0e1+1aqoq2j+HgDJicJU3OBAQI148IO5BSSZT3d3/WWjS4K2T+FwyYeaP Lwt9wgmHllANg== Date: Mon, 12 Apr 2021 10:51:40 +0300 From: Leon Romanovsky To: Gal Pressman Cc: Jason Gunthorpe , Doug Ledford , Yossi Leybovich , linux-rdma@vger.kernel.org, Alexander Matushevsky , Jason Gunthorpe , Peter Xu , Andrew Morton , Mike Kravetz Subject: Re: [PATCH for-next v3] RDMA/nldev: Add copy-on-fork attribute to get sys command Message-ID: References: <20210412064150.40064-1-galpress@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210412064150.40064-1-galpress@amazon.com> Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Mon, Apr 12, 2021 at 09:41:50AM +0300, Gal Pressman wrote: > 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 > --- > PR was sent: > https://github.com/linux-rdma/rdma-core/pull/975 > > Changelog - > 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 | 11 +++++++++++ > include/uapi/rdma/rdma_netlink.h | 2 ++ > 2 files changed, 13 insertions(+) > > diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c > index b8dc002a2478..4889e06a581a 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 +1698,16 @@ 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. > + */ > + nla_put_u8(msg, RDMA_NLDEV_SYS_ATTR_COPY_ON_FORK, 1); > + Nit, it is good to write here that we don't check nla_put_u8() on purpose. Thanks, Reviewed-by: Leon Romanovsky