From nobody Thu Feb 12 03:17:38 2026 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 CD505C77B7C for ; Fri, 28 Apr 2023 10:09:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345256AbjD1KJK (ORCPT ); Fri, 28 Apr 2023 06:09:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51050 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229519AbjD1KJG (ORCPT ); Fri, 28 Apr 2023 06:09:06 -0400 Received: from out-63.mta1.migadu.com (out-63.mta1.migadu.com [95.215.58.63]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A540268E for ; Fri, 28 Apr 2023 03:09:04 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1682676542; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=PVAO+BlDHMujnNKZN8jYnO3UHWhcSJNRlz/2YLsn0QQ=; b=PtApRLYmSe4NU9sJuZXacjEEDoHP1mUvWTAOjzUNY7o8SF1NHkhSVS+YleS4s7lmUzGlQ2 zrmrhV1KalImjhj7cWutu7WsxuZNpJjVsJeRb98zodWiH3EZOen6rrnJff00fV2Zxzib60 OeQR9ZEO9U7Ogw+A7sH+fyNN+747kwE= From: Yajun Deng To: david@redhat.com, osalvador@suse.de, akpm@linux-foundation.org, mhocko@suse.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yajun Deng Subject: [PATCH] mm/memory_hotplug: fix dead loop in offline_pages() Date: Fri, 28 Apr 2023 18:08:46 +0800 Message-Id: <20230428100846.95535-1-yajun.deng@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" When migration failure in do_migrate_range() and then the scan_movable_pages() will most likely return the same movable pfn. In this case, there is no condition to bail out, they will always run like this: ... [878020.623959] migrating pfn 1727813 failed ret:1 [878020.623960] page:00000000faa9673c refcount:3 mapcount:0 mapping:0000000= 0144ccd79 index:0x14280025 pfn:0x1727813 [878020.623962] memcg:ffffa0ff82d5a000 [878020.623962] aops:def_blk_aops ino:fd00001 [878020.623964] flags: 0x17ffffc000206a(referenced|dirty|active|workingset|= private|node=3D0|zone=3D2|lastcpupid=3D0x1fffff) [878020.623966] raw: 0017ffffc000206a ffffb0d14f50fbd8 ffffb0d14f50fbd8 fff= fa0ff9c155018 [878020.623967] raw: 0000000014280025 ffffa10327d702d8 00000003ffffffff fff= fa0ff82d5a000 [878020.623968] page dumped because: migration failure [878020.626196] migrating pfn 1727813 failed ret:1 [878020.626198] page:00000000faa9673c refcount:3 mapcount:0 mapping:0000000= 0144ccd79 index:0x14280025 pfn:0x1727813 [878020.626200] memcg:ffffa0ff82d5a000 [878020.626200] aops:def_blk_aops ino:fd00001 [878020.626202] flags: 0x17ffffc000206a(referenced|dirty|active|workingset|= private|node=3D0|zone=3D2|lastcpupid=3D0x1fffff) [878020.626204] raw: 0017ffffc000206a ffffb0d14f50fbd8 ffffb0d14f50fbd8 fff= fa0ff9c155018 [878020.626205] raw: 0000000014280025 ffffa10327d702d8 00000003ffffffff fff= fa0ff82d5a000 [878020.626206] page dumped because: migration failure ... Bail out when migration failures reach 3 times. Fixes: bb8965bd82fd ("mm, memory_hotplug: deobfuscate migration part of off= lining") Signed-off-by: Yajun Deng --- mm/memory_hotplug.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 8e0fa209d533..72dd385b8892 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1800,11 +1800,12 @@ int __ref offline_pages(unsigned long start_pfn, un= signed long nr_pages, struct zone *zone, struct memory_group *group) { const unsigned long end_pfn =3D start_pfn + nr_pages; - unsigned long pfn, system_ram_pages =3D 0; + unsigned long pfn, tmp_pfn, system_ram_pages =3D 0; const int node =3D zone_to_nid(zone); unsigned long flags; struct memory_notify arg; char *reason; + int count =3D 0; int ret; =20 /* @@ -1887,12 +1888,20 @@ int __ref offline_pages(unsigned long start_pfn, un= signed long nr_pages, =20 cond_resched(); =20 + tmp_pfn =3D pfn; ret =3D scan_movable_pages(pfn, end_pfn, &pfn); if (!ret) { - /* - * TODO: fatal migration failures should bail - * out - */ + if (pfn =3D=3D tmp_pfn) + count++; + else + count =3D 0; + + if (unlikely(count =3D=3D 3)) { + ret =3D -EBUSY; + reason =3D "migration failure"; + goto failed_removal_isolated; + } + do_migrate_range(pfn, end_pfn); } } while (!ret); --=20 2.25.1