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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 D0FBBC433EF for ; Fri, 17 Sep 2021 06:03:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B6A5D60F50 for ; Fri, 17 Sep 2021 06:03:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244941AbhIQGEW (ORCPT ); Fri, 17 Sep 2021 02:04:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232726AbhIQGEV (ORCPT ); Fri, 17 Sep 2021 02:04:21 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 575B5C061574 for ; Thu, 16 Sep 2021 23:03:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=KAOT1QriVAB4eECc9vz5PA1mRndKDvWQNMUrIEYWTzY=; b=jCZORZklm63UqwMLJXpjQ2dudy DYOj986Ojkr/OVt9ajFXRE8UE3zvbrF2FnBbfnN2JiljfGCOl+cxXH07SwrL8oFywRMkUiVnDKg5x CoL+AHQMfH3sOyqhCz5sIKvyTSE4EGUMdPBzEjoRafaG8YssbtlAmPZMgMvyKetgiFMo8NvCRMe8c MqvV8YtiHzSGESvrBSad03r3TxJhYuDpE1UeJdpK4M3zdNx17K33n9YRHxYD1CRuKOv5emRrZFKeH xYYX/FC+qRm4F9rWKjvBDbm6Ul2KYDBWS4CaVGpEH7pkH3dCR05nP0Jf5ITd0eNywEnUxBzvq72cj VDAh08BQ==; Received: from hch by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mR6vL-00HYMi-IS; Fri, 17 Sep 2021 06:01:06 +0000 Date: Fri, 17 Sep 2021 07:00:35 +0100 From: Christoph Hellwig To: Mike Christie Cc: stefanha@redhat.com, jasowang@redhat.com, mst@redhat.com, sgarzare@redhat.com, virtualization@lists.linux-foundation.org, christian.brauner@ubuntu.com, axboe@kernel.dk, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/8] fork: add helper to clone a process Message-ID: References: <20210916212051.6918-1-michael.christie@oracle.com> <20210916212051.6918-2-michael.christie@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210916212051.6918-2-michael.christie@oracle.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 16, 2021 at 04:20:44PM -0500, Mike Christie wrote: > The vhost layer has similar requirements as io_uring where its worker > threads need to access the userspace thread's memory, want to inherit the > parents's cgroups and namespaces, and be checked against the parent's > RLIMITs. Right now, the vhost layer uses the kthread API which has > kthread_use_mm for mem access, and those threads can use > cgroup_attach_task_all for v1 cgroups, but there are no helpers for the > other items. > > This adds a helper to clone a process so we can inherit everything we > want in one call. It's a more generic version of create_io_thread which > will be used by the vhost layer and io_uring in later patches in this set. > > This patch also exports __set_task_comm and wake_up_new_task which is > needed by modules to use the new helper. io_uring calls these functions > already but its always built into the kernel so was not needed before. Can you build proper APIs please? e.g. the set_task_comm users generally want a printf-like varargs caling conventions. I'd also much prefer to hide as much as possible in the actual helper. That is build a helper that gets the name, a flag to ignore the singals etc instead of exporting all these random low-level helpers.