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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 17A51C32750 for ; Fri, 2 Aug 2019 09:43:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5F0020679 for ; Fri, 2 Aug 2019 09:43:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564738994; bh=3b2N+zxazR7CX2RTeYYADRRfU7VrY1Byjv3Lv5J3Oyg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Wu2wTGgu9NLPGjeOJsvlD+plHLIOocAyX54K+l7OGrS7SrlUqJOfTwg3EV5Syo74f VMyuVN/X4Z4BwHIgc1XQEJxZXjrDdrw0pl02d3bBC1MTlRW3P2OqvTq63wyTTC56wA lrf+gglJU+WKJjP/NV+/L2yypqb2wICMhauvqc/E= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391681AbfHBJnN (ORCPT ); Fri, 2 Aug 2019 05:43:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:45950 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405037AbfHBJnK (ORCPT ); Fri, 2 Aug 2019 05:43:10 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 41A4F2087E; Fri, 2 Aug 2019 09:43:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564738989; bh=3b2N+zxazR7CX2RTeYYADRRfU7VrY1Byjv3Lv5J3Oyg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YaaDNkZ6gZEWZB8YxlIDavOPAfXIKXCLLIJntA91I3hy5oEUXlAKJsB5pta5hhlAF ZSZLhgaU9Cn5dEZhd1ikYqTkPkgAhMEtUpSi/jt1cRxhr7FLN1v6RHU7g4qAm3Yxxm EUTkGoLfiJHksL6NbmnpNvfIYBL2WhVdOXQyVuuk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Juergen Gross Subject: [PATCH 4.9 074/223] xen: let alloc_xenballooned_pages() fail if not enough memory free Date: Fri, 2 Aug 2019 11:34:59 +0200 Message-Id: <20190802092243.634454390@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190802092238.692035242@linuxfoundation.org> References: <20190802092238.692035242@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Juergen Gross commit a1078e821b605813b63bf6bca414a85f804d5c66 upstream. Instead of trying to allocate pages with GFP_USER in add_ballooned_pages() check the available free memory via si_mem_available(). GFP_USER is far less limiting memory exhaustion than the test via si_mem_available(). This will avoid dom0 running out of memory due to excessive foreign page mappings especially on ARM and on x86 in PVH mode, as those don't have a pre-ballooned area which can be used for foreign mappings. As the normal ballooning suffers from the same problem don't balloon down more than si_mem_available() pages in one iteration. At the same time limit the default maximum number of retries. This is part of XSA-300. Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman --- drivers/xen/balloon.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -591,8 +591,15 @@ static void balloon_process(struct work_ state = reserve_additional_memory(); } - if (credit < 0) - state = decrease_reservation(-credit, GFP_BALLOON); + if (credit < 0) { + long n_pages; + + n_pages = min(-credit, si_mem_available()); + state = decrease_reservation(n_pages, GFP_BALLOON); + if (state == BP_DONE && n_pages != -credit && + n_pages < totalreserve_pages) + state = BP_EAGAIN; + } state = update_schedule(state); @@ -631,6 +638,9 @@ static int add_ballooned_pages(int nr_pa } } + if (si_mem_available() < nr_pages) + return -ENOMEM; + st = decrease_reservation(nr_pages, GFP_USER); if (st != BP_DONE) return -ENOMEM; @@ -754,7 +764,7 @@ static int __init balloon_init(void) balloon_stats.schedule_delay = 1; balloon_stats.max_schedule_delay = 32; balloon_stats.retry_count = 1; - balloon_stats.max_retry_count = RETRY_UNLIMITED; + balloon_stats.max_retry_count = 4; #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG set_online_page_callback(&xen_online_page);