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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09228C433FE for ; Wed, 23 Nov 2022 10:43:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235606AbiKWKnN (ORCPT ); Wed, 23 Nov 2022 05:43:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44220 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235971AbiKWKls (ORCPT ); Wed, 23 Nov 2022 05:41:48 -0500 Received: from outbound-smtp14.blacknight.com (outbound-smtp14.blacknight.com [46.22.139.231]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6F1585A12 for ; Wed, 23 Nov 2022 02:25:54 -0800 (PST) Received: from mail.blacknight.com (pemlinmail06.blacknight.ie [81.17.255.152]) by outbound-smtp14.blacknight.com (Postfix) with ESMTPS id 519271C3B31 for ; Wed, 23 Nov 2022 10:25:53 +0000 (GMT) Received: (qmail 2725 invoked from network); 23 Nov 2022 10:25:53 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.198.246]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 23 Nov 2022 10:25:52 -0000 Date: Wed, 23 Nov 2022 10:25:50 +0000 From: Mel Gorman To: "Akira Naribayashi (Fujitsu)" Cc: "akpm@linux-foundation.org" , "vbabka@suse.cz" , "rientjes@google.com" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: Re: [PATCH] mm, compaction: fix fast_isolate_around() to stay within boundaries Message-ID: <20221123102550.kbsd3xclsr6o27up@techsingularity.net> References: <20221027132557.5f724149bd5753036f41512a@linux-foundation.org> <20221031073559.36021-1-a.naribayashi@fujitsu.com> <20221107154350.34brdl3ms2ve5wud@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Wed, Nov 09, 2022 at 05:41:12AM +0000, Akira Naribayashi (Fujitsu) wrote: > On Mon, 7 Nov 2022 15:43:56 +0000, Mei Gorman wrote: > > On Mon, Nov 07, 2022 at 12:32:34PM +0000, Akira Naribayashi (Fujitsu) wrote: > > > > Under what circumstances will this panic occur? I assume those > > > > circumstnces are pretty rare, give that 6e2b7044c1992 was nearly two > > > > years ago. > > > > > > > > Did you consider the desirability of backporting this fix into earlier > > > > kernels? > > > > > > > > > Panic can occur on systems with multiple zones in a single pageblock. > > > > > > > Please provide an example of the panic and the zoneinfo. > > This issue is occurring in our customer's environment and cannot > be shared publicly as it contains customer information. > Also, the panic is occurring with the kernel in RHEL and may not > panic with Upstream's community kernel. > In other words, it is possible to panic on older kernels. > I think this fix should be backported to stable kernel series. > > > > The reason it is rare is that it only happens in special configurations. > > > > How is this special configuration created? > > This is the case when the node boundary is not aligned to pageblock boundary. In that case, does this work to avoid rescanning an area that was already isolated? diff --git a/mm/compaction.c b/mm/compaction.c index c51f7f545afe..58cf73ff20ff 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1346,7 +1346,7 @@ move_freelist_tail(struct list_head *freelist, struct page *freepage) static void fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long nr_isolated) { - unsigned long start_pfn, end_pfn; + unsigned long start_pfn, end_pfn, isolated_end; struct page *page; /* Do not search around if there are enough pages already */ @@ -1361,6 +1361,10 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long start_pfn = max(pageblock_start_pfn(pfn), cc->zone->zone_start_pfn); end_pfn = min(pageblock_end_pfn(pfn), zone_end_pfn(cc->zone)); + /* Pageblock may straddle zone/node boundaries */ + isolated_end = pfn + nr_isolated; + pfn = clamp(pfn, start_pfn, end_pfn); + page = pageblock_pfn_to_page(start_pfn, end_pfn, cc->zone); if (!page) return; @@ -1373,7 +1377,7 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long } /* Scan after */ - start_pfn = pfn + nr_isolated; + start_pfn = isolated_end; if (start_pfn < end_pfn) isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false);