From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965138AbcALQ4f (ORCPT ); Tue, 12 Jan 2016 11:56:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44731 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934239AbcALQ4d (ORCPT ); Tue, 12 Jan 2016 11:56:33 -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 v4 2/2] xen_balloon: support memory auto onlining policy Date: Tue, 12 Jan 2016 17:56:17 +0100 Message-Id: <1452617777-10598-3-git-send-email-vkuznets@redhat.com> In-Reply-To: <1452617777-10598-1-git-send-email-vkuznets@redhat.com> References: <1452617777-10598-1-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 --- drivers/xen/Kconfig | 20 +++++++++++++------- drivers/xen/balloon.c | 30 +++++++++++++++++++----------- 2 files changed, 32 insertions(+), 18 deletions(-) diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index 73708ac..098ab49 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) domU: ensure that memory auto online policy is in effect by + checking /sys/devices/system/memory/auto_online_blocks file + (should be 'online'). + + 2) dom0: xl mem-max where is >= requested memory size, - 2) dom0: xl mem-set + 3) dom0: 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 domU 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..68f0aa2 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -284,7 +284,7 @@ static void release_memory_resource(struct resource *resource) kfree(resource); } -static enum bp_state reserve_additional_memory(void) +static enum bp_state reserve_additional_memory(bool online) { long credit; struct resource *resource; @@ -338,7 +338,18 @@ 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. It is safe because there can only be + * one balloon_process() running at a time and balloon_mutex is + * internal to Xen driver, generic memory hotplug code doesn't mess + * with it. + */ + mutex_unlock(&balloon_mutex); + rc = add_memory_resource(nid, resource, online); + mutex_lock(&balloon_mutex); + if (rc) { pr_warn("Cannot add additional memory (%i)\n", rc); goto err; @@ -562,14 +573,11 @@ static void balloon_process(struct work_struct *work) credit = current_credit(); - if (credit > 0) { - if (balloon_is_inflated()) - state = increase_reservation(credit); - else - state = reserve_additional_memory(); - } - - if (credit < 0) + if (credit > 0 && balloon_is_inflated()) + state = increase_reservation(credit); + else if (credit > 0) + state = reserve_additional_memory(memhp_auto_online); + else if (credit < 0) state = decrease_reservation(-credit, GFP_BALLOON); state = update_schedule(state); @@ -599,7 +607,7 @@ static int add_ballooned_pages(int nr_pages) enum bp_state st; if (xen_hotplug_unpopulated) { - st = reserve_additional_memory(); + st = reserve_additional_memory(false); if (st != BP_ECANCELED) { mutex_unlock(&balloon_mutex); wait_event(balloon_wq, -- 2.5.0