From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755816AbcAMRcv (ORCPT ); Wed, 13 Jan 2016 12:32:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33705 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755746AbcAMRcr (ORCPT ); Wed, 13 Jan 2016 12:32:47 -0500 From: Vitaly Kuznetsov To: linux-mm@kvack.org Cc: Jonathan Corbet , Greg Kroah-Hartman , Daniel Kiper , Dan Williams , Tang Chen , David Vrabel , David Rientjes , Andrew Morton , Naoya Horiguchi , Xishi Qiu , Mel Gorman , "K. Y. Srinivasan" , Igor Mammedov , Kay Sievers , Konrad Rzeszutek Wilk , Boris Ostrovsky , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org Subject: [PATCH v5 2/2] xen_balloon: support memory auto onlining policy Date: Wed, 13 Jan 2016 18:32:30 +0100 Message-Id: <1452706350-21158-3-git-send-email-vkuznets@redhat.com> In-Reply-To: <1452706350-21158-1-git-send-email-vkuznets@redhat.com> References: <1452706350-21158-1-git-send-email-vkuznets@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add support for the newly added kernel memory auto onlining policy to Xen ballon driver. Suggested-by: Daniel Kiper Signed-off-by: Vitaly Kuznetsov --- Changes since v4: - 'dom0' -> 'control domain', 'domU' -> 'target domain' in Kconfig [David Vrabel] - always call add_memory_resource() with memhp_auto_online [David Vrabel] --- drivers/xen/Kconfig | 20 +++++++++++++------- drivers/xen/balloon.c | 11 ++++++++++- 2 files changed, 23 insertions(+), 8 deletions(-) diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index 73708ac..addcb7f 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -37,23 +37,29 @@ config XEN_BALLOON_MEMORY_HOTPLUG Memory could be hotplugged in following steps: - 1) dom0: xl mem-max + 1) target domain: ensure that memory auto online policy is in + effect by checking /sys/devices/system/memory/auto_online_blocks + file (should be 'online'). + + 2) control domain: xl mem-max where is >= requested memory size, - 2) dom0: xl mem-set + 3) control domain: xl mem-set where is requested memory size; alternatively memory could be added by writing proper value to /sys/devices/system/xen_memory/xen_memory0/target or /sys/devices/system/xen_memory/xen_memory0/target_kb on dumU, - 3) domU: for i in /sys/devices/system/memory/memory*/state; do \ - [ "`cat "$i"`" = offline ] && echo online > "$i"; done + Alternatively, if memory auto onlining was not requested at step 1 + the newly added memory can be manually onlined in the target domain + by doing the following: - Memory could be onlined automatically on domU by adding following line to udev rules: + for i in /sys/devices/system/memory/memory*/state; do \ + [ "`cat "$i"`" = offline ] && echo online > "$i"; done - SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'" + or by adding the following line to udev rules: - In that case step 3 should be omitted. + SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'" config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT int "Hotplugged memory limit (in GiB) for a PV guest" diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 890c3b5..f8cca0c 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -338,7 +338,16 @@ static enum bp_state reserve_additional_memory(void) } #endif - rc = add_memory_resource(nid, resource, false); + /* + * add_memory_resource() will call online_pages() which in its turn + * will call xen_online_page() callback causing deadlock if we don't + * release balloon_mutex here. Unlocking here is safe because the + * callers drop the mutex before trying again. + */ + mutex_unlock(&balloon_mutex); + rc = add_memory_resource(nid, resource, memhp_auto_online); + mutex_lock(&balloon_mutex); + if (rc) { pr_warn("Cannot add additional memory (%i)\n", rc); goto err; -- 2.5.0