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=-8.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 313B4C43613 for ; Thu, 20 Jun 2019 09:40:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 05B7E2080C for ; Thu, 20 Jun 2019 09:40:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731005AbfFTJkT (ORCPT ); Thu, 20 Jun 2019 05:40:19 -0400 Received: from mx2.suse.de ([195.135.220.15]:49268 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725937AbfFTJkT (ORCPT ); Thu, 20 Jun 2019 05:40:19 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 795A9AED4; Thu, 20 Jun 2019 09:40:18 +0000 (UTC) From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Alexander Duyck Subject: [PATCH RFC] mm: fix regression with deferred struct page init Date: Thu, 20 Jun 2019 11:40:15 +0200 Message-Id: <20190620094015.21206-1-jgross@suse.com> X-Mailer: git-send-email 2.16.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 0e56acae4b4dd4a9 ("mm: initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections") is causing a regression on some systems when the kernel is booted as Xen dom0. The system will just hang in early boot. Reason is an endless loop in get_page_from_freelist() in case the first zone looked at has no free memory. deferred_grow_zone() is always returning true due to the following code snipplet: /* If the zone is empty somebody else may have cleared out the zone */ if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, first_deferred_pfn)) { pgdat->first_deferred_pfn = ULONG_MAX; pgdat_resize_unlock(pgdat, &flags); return true; } This in turn results in the loop as get_page_from_freelist() is assuming forward progress can be made by doing some more struct page initialization. Fixes: 0e56acae4b4dd4a9 ("mm: initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections") --- This patch makes my system boot again as Xen dom0, but I'm not really sure it is the correct way to do it, hence the RFC. Signed-off-by: Juergen Gross --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d66bc8abe0af..6ee754b5cd92 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1826,7 +1826,7 @@ deferred_grow_zone(struct zone *zone, unsigned int order) first_deferred_pfn)) { pgdat->first_deferred_pfn = ULONG_MAX; pgdat_resize_unlock(pgdat, &flags); - return true; + return false; } /* -- 2.16.4