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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 E1DABC48BD4 for ; Tue, 25 Jun 2019 08:25:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C4FA52168B for ; Tue, 25 Jun 2019 08:25:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730178AbfFYIZf (ORCPT ); Tue, 25 Jun 2019 04:25:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:42732 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726702AbfFYIZf (ORCPT ); Tue, 25 Jun 2019 04:25:35 -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 E6254AEEE; Tue, 25 Jun 2019 08:25:33 +0000 (UTC) Subject: Re: [PATCH] mm: fix regression with deferred struct page init To: xen-devel@lists.xenproject.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Alexander Duyck References: <20190620160821.4210-1-jgross@suse.com> From: Juergen Gross Message-ID: <79797c17-58d6-b09c-3aad-73e375a7f208@suse.com> Date: Tue, 25 Jun 2019 10:25:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190620160821.4210-1-jgross@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: de-DE Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Gentle ping. I'd really like to have that in 5.2 in order to avoid the regression introduced with 5.2-rc1. Juergen On 20.06.19 18:08, Juergen Gross wrote: > 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. > > Cc: Alexander Duyck > Fixes: 0e56acae4b4dd4a9 ("mm: initialize MAX_ORDER_NR_PAGES at a time instead of doing larger sections") > Suggested-by: Alexander Duyck > Signed-off-by: Juergen Gross > --- > mm/page_alloc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d66bc8abe0af..8e3bc949ebcc 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1826,7 +1826,8 @@ 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; > + /* Retry only once. */ > + return first_deferred_pfn != ULONG_MAX; > } > > /* >