From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755273AbcHSMqK (ORCPT ); Fri, 19 Aug 2016 08:46:10 -0400 Received: from outbound-smtp05.blacknight.com ([81.17.249.38]:34348 "EHLO outbound-smtp05.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755118AbcHSMpM (ORCPT ); Fri, 19 Aug 2016 08:45:12 -0400 Date: Fri, 19 Aug 2016 13:45:08 +0100 From: Mel Gorman To: Pankaj Gupta Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz, riel@redhat.com, hannes@cmpxchg.org, iamjoonsoo.kim@lge.com, kirill.shutemov@linux.intel.com, izumi.taku@jp.fujitsu.com Subject: Re: [PATCH] mm: Add WARN_ON for possibility of infinite loop if empty lists in free_pcppages_bulk' Message-ID: <20160819124508.GM8119@techsingularity.net> References: <1471608918-5101-1-git-send-email-pagupta@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1471608918-5101-1-git-send-email-pagupta@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 19, 2016 at 05:45:18PM +0530, Pankaj Gupta wrote: > While debugging issue in realtime kernel i found a scenario > which resulted in infinite loop resulting because of empty pcp->lists > and valid 'to_free' value. This patch is to add 'WARN_ON' in function > 'free_pcppages_bulk' if there is possibility of infinite loop because > of any bug in code. > What was the bug that allowed this situation to occur? It would imply the pcp count was somehow out of sync. -- Mel Gorman SUSE Labs