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[2620:137:e000::1:20]) by mx.google.com with ESMTP id x145-20020a633197000000b00478e7f850f5si2514452pgx.320.2022.12.16.03.05.56; Fri, 16 Dec 2022 03:06:13 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230022AbiLPKZP (ORCPT + 68 others); Fri, 16 Dec 2022 05:25:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230396AbiLPKYo (ORCPT ); Fri, 16 Dec 2022 05:24:44 -0500 Received: from outbound-smtp39.blacknight.com (outbound-smtp39.blacknight.com [46.22.139.222]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72AD250D4B for ; Fri, 16 Dec 2022 02:24:17 -0800 (PST) Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp39.blacknight.com (Postfix) with ESMTPS id 04C951C61 for ; Fri, 16 Dec 2022 10:24:16 +0000 (GMT) Received: (qmail 5411 invoked from network); 16 Dec 2022 10:24:15 -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); 16 Dec 2022 10:24:15 -0000 Date: Fri, 16 Dec 2022 10:24:10 +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: <20221216102410.hem6wxqyqf43vnnp@techsingularity.net> References: <20221027132557.5f724149bd5753036f41512a@linux-foundation.org> <20221031073559.36021-1-a.naribayashi@fujitsu.com> <20221107154350.34brdl3ms2ve5wud@techsingularity.net> <20221123102550.kbsd3xclsr6o27up@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_LOW, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 09, 2022 at 09:19:37AM +0000, Akira Naribayashi (Fujitsu) wrote: > On Wed, 23 Nov 2022 10:26:05 +0000, Mei Gorman wrote: > > 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? > > In the case of your patch, I think I need to clamp the isolated_end as well. > Because sometimes isolated_end < start_pfn(value before entering Scan after) < end_pfn. > > After re-reading the source, I think the problem is that min_pfn and low_pfn > can be out of range in fast_isolate_freepages. > How about the following patch? > Ok, makes sense and it is a condition that could happen because of pageblock alignment. -- Mel Gorman SUSE Labs