From patchwork Mon Mar 30 14:47:12 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 213169 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=-8.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SPF_HELO_NONE, SPF_PASS autolearn=unavailable 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 F4058C2D0E5 for ; Mon, 30 Mar 2020 14:47:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D3DC12072E for ; Mon, 30 Mar 2020 14:47:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728034AbgC3OrP (ORCPT ); Mon, 30 Mar 2020 10:47:15 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:58993 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727522AbgC3OrP (ORCPT ); Mon, 30 Mar 2020 10:47:15 -0400 Received: from bigeasy by Galois.linutronix.de with local (Exim 4.80) (envelope-from ) id 1jIvh2-0006lt-I5; Mon, 30 Mar 2020 16:47:12 +0200 Date: Mon, 30 Mar 2020 16:47:12 +0200 From: Sebastian Andrzej Siewior To: Thomas Gleixner Cc: LKML , linux-rt-users , Steven Rostedt Subject: [ANNOUNCE] v5.4.28-rt19 Message-ID: <20200330144712.cwcz5ejal4ankeoi@linutronix.de> MIME-Version: 1.0 Content-Disposition: inline Sender: linux-rt-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org Dear RT folks! I'm pleased to announce the v5.4.28-rt19 patch set. Changes since v5.4.28-rt18: - Memory compaction of unevictable pages has been disabled in the v5.4 release. This aligns the change with what has been prepared for upstream: Disable is by default on PREEMPT_RT (/proc/sys/vm/compact_unevictable_allowed reads 0) but allow enabling it which will trigger a warning. Known issues - It has been pointed out that due to changes to the printk code the internal buffer representation changed. This is only an issue if tools like `crash' are used to extract the printk buffer from a kernel memory image. The delta patch against v5.4.28-rt18 is appended below and can be found here: https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.4/incr/patch-5.4.28-rt18-rt19.patch.xz You can get this release via the git tree at: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.4.28-rt19 The RT patch against v5.4.28 can be found here: https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patch-5.4.28-rt19.patch.xz The split quilt queue is available at: https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patches-5.4.28-rt19.tar.xz Sebastian diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst index 64aeee1009cab..0329a4d3fa9ec 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -128,6 +128,9 @@ allowed to examine the unevictable lru (mlocked pages) for pages to compact. This should be used on systems where stalls for minor page faults are an acceptable trade for large contiguous free memory. Set to 0 to prevent compaction from moving pages that are unevictable. Default value is 1. +On CONFIG_PREEMPT_RT the default value is 0 in order to avoid a page fault, due +to compaction, which would block the task from becomming active until the fault +is resolved. dirty_background_bytes diff --git a/kernel/sysctl.c b/kernel/sysctl.c index d08bd51a0fbc3..8221219d65c35 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -212,6 +212,11 @@ static int proc_do_cad_pid(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos); static int proc_taint(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos); +#ifdef CONFIG_COMPACTION +static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table, + int write, void __user *buffer, + size_t *lenp, loff_t *ppos); +#endif #endif #ifdef CONFIG_PRINTK @@ -1488,17 +1493,16 @@ static struct ctl_table vm_table[] = { .extra1 = &min_extfrag_threshold, .extra2 = &max_extfrag_threshold, }, -#ifndef CONFIG_PREEMPT_RT { .procname = "compact_unevictable_allowed", .data = &sysctl_compact_unevictable_allowed, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec, + .proc_handler = proc_dointvec_minmax_warn_RT_change, .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, -#endif + #endif /* CONFIG_COMPACTION */ { .procname = "min_free_kbytes", @@ -2582,6 +2586,28 @@ int proc_dointvec(struct ctl_table *table, int write, return do_proc_dointvec(table, write, buffer, lenp, ppos, NULL, NULL); } +#ifdef CONFIG_COMPACTION +static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table, + int write, void __user *buffer, + size_t *lenp, loff_t *ppos) +{ + int ret, old; + + if (!IS_ENABLED(CONFIG_PREEMPT_RT) || !write) + return proc_dointvec_minmax(table, write, buffer, lenp, ppos); + + old = *(int *)table->data; + ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); + if (ret) + return ret; + if (old != *(int *)table->data) + pr_warn_once("sysctl attribute %s changed by %s[%d]\n", + table->procname, current->comm, + task_pid_nr(current)); + return ret; +} +#endif + /** * proc_douintvec - read a vector of unsigned integers * @table: the sysctl table diff --git a/localversion-rt b/localversion-rt index 9e7cd66d9f44f..483ad771f201a 100644 --- a/localversion-rt +++ b/localversion-rt @@ -1 +1 @@ --rt18 +-rt19 diff --git a/mm/compaction.c b/mm/compaction.c index 83cc3d1e5df7b..31e6e103f38b4 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1591,7 +1591,7 @@ typedef enum { * compactable pages. */ #ifdef CONFIG_PREEMPT_RT -#define sysctl_compact_unevictable_allowed 0 +int sysctl_compact_unevictable_allowed __read_mostly = 0; #else int sysctl_compact_unevictable_allowed __read_mostly = 1; #endif