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 C5D6EC4167B for ; Fri, 16 Dec 2022 10:33:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229636AbiLPKdS (ORCPT ); Fri, 16 Dec 2022 05:33:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230281AbiLPKdD (ORCPT ); Fri, 16 Dec 2022 05:33:03 -0500 X-Greylist: delayed 524 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Fri, 16 Dec 2022 02:33:01 PST Received: from outbound-smtp60.blacknight.com (outbound-smtp60.blacknight.com [46.22.136.244]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A68B050D48 for ; Fri, 16 Dec 2022 02:33:01 -0800 (PST) Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp60.blacknight.com (Postfix) with ESMTPS id 0D662FAA4D 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: Precedence: bulk List-ID: X-Mailing-List: stable@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