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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 A8E3BC43460 for ; Fri, 30 Apr 2021 19:53:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FBD561474 for ; Fri, 30 Apr 2021 19:53:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233684AbhD3Tx7 (ORCPT ); Fri, 30 Apr 2021 15:53:59 -0400 Received: from server.lespinasse.org ([63.205.204.226]:56935 "EHLO server.lespinasse.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232335AbhD3TxY (ORCPT ); Fri, 30 Apr 2021 15:53:24 -0400 DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=lespinasse.org; i=@lespinasse.org; q=dns/txt; s=srv-14-ed; t=1619812353; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : from; bh=0J/hy/JQlPleTiIXPLrlBogxDyG+sG63ZteLm7sGfKo=; b=wyAG608rKGunu7qqRpNcV3RhywqilJmsoDkuatV7pMb2CuBB2Z5fN14HlhxI88n50qQXn JOext8U+9dt1WmYDA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lespinasse.org; i=@lespinasse.org; q=dns/txt; s=srv-14-rsa; t=1619812353; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : from; bh=0J/hy/JQlPleTiIXPLrlBogxDyG+sG63ZteLm7sGfKo=; b=I7GqfkMzcJrmxSVWKzaFi3Mbfg0My9nLk6La+4wSu0ynTAHGbVd/YLF+eo94NlSin0y2x 5UJRM0G2jchXTm699A4f2yZErshAfuGTcwTU1+KKv7fPd1guFKelgOEdbBOltZG1xjZF6Hr cu7453EsgVC4XX/ZmrD7UtuP5ToQJjNcX3bWRZE95xJsL4I79FyjIFIr80NBa5p4b08KDHM XKTi1v+b5tKZc28JAcJGdSPPF4ww/d2hsg//WZqoozCHPYBVygjUUATnUIQ147goNNaLGCk M9dUpDnqaZNX8DgV5FOjh+BWX1KVhPjjD8OvB/QV47TAysg3vXstHO+Jy0Lw== Received: from zeus.lespinasse.org (zeus.lespinasse.org [IPv6:fd00::150:0]) by server.lespinasse.org (Postfix) with ESMTPS id 531B2160320; Fri, 30 Apr 2021 12:52:33 -0700 (PDT) Received: by zeus.lespinasse.org (Postfix, from userid 1000) id 44ACA19F522; Fri, 30 Apr 2021 12:52:33 -0700 (PDT) From: Michel Lespinasse To: Linux-MM , Linux-Kernel Cc: Laurent Dufour , Peter Zijlstra , Michal Hocko , Matthew Wilcox , Rik van Riel , Paul McKenney , Andrew Morton , Suren Baghdasaryan , Joel Fernandes , Andy Lutomirski , Michel Lespinasse Subject: [PATCH 11/29] mm: rcu safe vma freeing Date: Fri, 30 Apr 2021 12:52:12 -0700 Message-Id: <20210430195232.30491-12-michel@lespinasse.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210430195232.30491-1-michel@lespinasse.org> References: <20210430195232.30491-1-michel@lespinasse.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This prepares for speculative page faults looking up and copying vmas under protection of an rcu read lock, instead of the usual mmap read lock. Note - it might also be feasible to just use SLAB_TYPESAFE_BY_RCU when creating the vm_area_cachep, but that's probably too subtle to consider here. Signed-off-by: Michel Lespinasse --- include/linux/mm_types.h | 16 +++++++++++----- kernel/fork.c | 13 +++++++++++++ 2 files changed, 24 insertions(+), 5 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 70882e628908..024970635921 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -304,12 +304,18 @@ struct vm_userfaultfd_ctx {}; struct vm_area_struct { /* The first cache line has the info for VMA tree walking. */ - unsigned long vm_start; /* Our start address within vm_mm. */ - unsigned long vm_end; /* The first byte after our end address - within vm_mm. */ + union { + struct { + /* VMA covers [vm_start; vm_end) addresses within mm */ + unsigned long vm_start, vm_end; - /* linked list of VM areas per task, sorted by address */ - struct vm_area_struct *vm_next, *vm_prev; + /* linked list of VMAs per task, sorted by address */ + struct vm_area_struct *vm_next, *vm_prev; + }; +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT + struct rcu_head vm_rcu; /* Used for deferred freeing. */ +#endif + }; struct rb_node vm_rb; diff --git a/kernel/fork.c b/kernel/fork.c index 426cd0c51f9e..7c22bf2b1f9d 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -369,9 +369,22 @@ struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) return new; } +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT +static void __vm_area_free(struct rcu_head *head) +{ + struct vm_area_struct *vma = container_of(head, struct vm_area_struct, + vm_rcu); + kmem_cache_free(vm_area_cachep, vma); +} +#endif + void vm_area_free(struct vm_area_struct *vma) { +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT + call_rcu(&vma->vm_rcu, __vm_area_free); +#else kmem_cache_free(vm_area_cachep, vma); +#endif } static void account_kernel_stack(struct task_struct *tsk, int account) -- 2.20.1