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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,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 34603C7618B for ; Fri, 26 Jul 2019 13:48:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C98B22CD8 for ; Fri, 26 Jul 2019 13:48:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564148903; bh=Ev4bULy0h2A0hB7svWgw9Hev4kR3poghVKw8Ioiju5U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ymPkK0HVGUSNg+Vsh4b37drspNJ8bGYxbxzX8GMVMFXyq7sHjt+/ExKTGsGtuP/dP cr4J/R/czuJ8KWwHvKhLcZEEVeGkT24X9qtwxyWkCo5O5yMbbg7if1tUnSwPtUdasS ihp7/9jJ2dq7pRqR1dBeTEbIkUrP0rXks5XgaVo4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388469AbfGZNsW (ORCPT ); Fri, 26 Jul 2019 09:48:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:54156 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388518AbfGZNpR (ORCPT ); Fri, 26 Jul 2019 09:45:17 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D93D322CEC; Fri, 26 Jul 2019 13:45:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564148717; bh=Ev4bULy0h2A0hB7svWgw9Hev4kR3poghVKw8Ioiju5U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Up07vSW62WTO8PStfRc9SEYrs+inhN1iwad8Ptz0K7yRHqG06HU8aA+7DRGR33Wde vVMnxi+1xNlLTVK8jXpdRSkXtxAMJ3Sndz+hykZoeP31xGpUcVZ6XtYktB7rNEtvfn k4fKeQ9/zsgwL2TLywBG9keq2nfYO8VOcGh07TgU= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Juergen Gross , Sasha Levin Subject: [PATCH AUTOSEL 4.9 28/30] xen: let alloc_xenballooned_pages() fail if not enough memory free Date: Fri, 26 Jul 2019 09:44:30 -0400 Message-Id: <20190726134432.12993-28-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190726134432.12993-1-sashal@kernel.org> References: <20190726134432.12993-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Juergen Gross [ Upstream commit a1078e821b605813b63bf6bca414a85f804d5c66 ] 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: Sasha Levin --- drivers/xen/balloon.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index e4db19e88ab1..6af117af9780 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -591,8 +591,15 @@ static void balloon_process(struct work_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_pages) } } + 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); -- 2.20.1