From patchwork Wed Jan 22 09:28:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 233619 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,USER_AGENT_GIT 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 0173CC2D0DB for ; Wed, 22 Jan 2020 09:30:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB5102467A for ; Wed, 22 Jan 2020 09:30:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579685436; bh=FsfF4NfcdYAvMcZURswP/E6Pd7la1YZs0Ix6zZrUEiU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hOAf4pJVw6XMiaGEIsL+DEpm2giPzWd9vSKIN4WqTbc3SsIPmBXhR95y0ebxXKZhN 5T7lfStyyAEJQ3XssTEKtLdWVrS+jljxpj/ZbfwwOBdO/lrWqfwAGs3nPa2ySMfDqN cq3QRBPRiBZmCgKw1x6jewkBvjleuzPeoSaf02c4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729165AbgAVJac (ORCPT ); Wed, 22 Jan 2020 04:30:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:41984 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725911AbgAVJab (ORCPT ); Wed, 22 Jan 2020 04:30:31 -0500 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 064802467A; Wed, 22 Jan 2020 09:30:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579685431; bh=FsfF4NfcdYAvMcZURswP/E6Pd7la1YZs0Ix6zZrUEiU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WO9OmUR4H0JNQcXu/vkpceApO2JZPz/JiZtB8cntHu5dZu6eMD4mkaYm8lnWC0nlG qb2k4h9ohrKz4M6/yv1CkIhukTqDJSNxEtoUeQLRp8DRdwbEwiOw37jtcqw6YopfCv wqR6hLwA+3rYgOZIToLzLtsIcdwi1LVmguW5+B7o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Juergen Gross , Ben Hutchings Subject: [PATCH 4.4 12/76] xen: let alloc_xenballooned_pages() fail if not enough memory free Date: Wed, 22 Jan 2020 10:28:28 +0100 Message-Id: <20200122092752.831204783@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200122092751.587775548@linuxfoundation.org> References: <20200122092751.587775548@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 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: Ben Hutchings 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 @@ -584,8 +584,15 @@ 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); @@ -624,6 +631,9 @@ 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; @@ -747,7 +757,7 @@ 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);