From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-f200.google.com (mail-oi1-f200.google.com [209.85.167.200]) by kanga.kvack.org (Postfix) with ESMTP id C91C06B0966 for ; Fri, 16 Nov 2018 07:04:56 -0500 (EST) Received: by mail-oi1-f200.google.com with SMTP id w80so4831775oiw.19 for ; Fri, 16 Nov 2018 04:04:56 -0800 (PST) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id j37si12535839oth.260.2018.11.16.04.04.55 for ; Fri, 16 Nov 2018 04:04:55 -0800 (PST) Subject: Re: [PATCH 4/5] mm, memory_hotplug: print reason for the offlining failure References: <20181116083020.20260-1-mhocko@kernel.org> <20181116083020.20260-5-mhocko@kernel.org> From: Anshuman Khandual Message-ID: Date: Fri, 16 Nov 2018 17:34:50 +0530 MIME-Version: 1.0 In-Reply-To: <20181116083020.20260-5-mhocko@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Andrew Morton Cc: Oscar Salvador , Baoquan He , linux-mm@kvack.org, LKML , Michal Hocko On 11/16/2018 02:00 PM, Michal Hocko wrote: > From: Michal Hocko > > The memory offlining failure reporting is inconsistent and insufficient. > Some error paths simply do not report the failure to the log at all. > When we do report there are no details about the reason of the failure > and there are several of them which makes memory offlining failures > hard to debug. > > Make sure that the > memory offlining [mem %#010llx-%#010llx] failed > message is printed for all failures and also provide a short textual > reason for the failure e.g. > > [ 1984.506184] rac1 kernel: memory offlining [mem 0x82600000000-0x8267fffffff] failed due to signal backoff > > this tells us that the offlining has failed because of a signal pending > aka user intervention. > > [akpm: tweak messages a bit] > Signed-off-by: Michal Hocko > --- > mm/memory_hotplug.c | 34 +++++++++++++++++++++++----------- > 1 file changed, 23 insertions(+), 11 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index a92b1b8f6218..88d50e74e3fe 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1553,6 +1553,7 @@ static int __ref __offline_pages(unsigned long start_pfn, > unsigned long valid_start, valid_end; > struct zone *zone; > struct memory_notify arg; > + char *reason; > > mem_hotplug_begin(); > > @@ -1561,7 +1562,9 @@ static int __ref __offline_pages(unsigned long start_pfn, > if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, > &valid_end)) { > mem_hotplug_done(); > - return -EINVAL; > + ret = -EINVAL; > + reason = "multizone range"; > + goto failed_removal; > } > > zone = page_zone(pfn_to_page(valid_start)); > @@ -1573,7 +1576,8 @@ static int __ref __offline_pages(unsigned long start_pfn, > MIGRATE_MOVABLE, true); > if (ret) { > mem_hotplug_done(); > - return ret; > + reason = "failure to isolate range"; > + goto failed_removal; > } > > arg.start_pfn = start_pfn; > @@ -1582,15 +1586,19 @@ static int __ref __offline_pages(unsigned long start_pfn, > > ret = memory_notify(MEM_GOING_OFFLINE, &arg); > ret = notifier_to_errno(ret); > - if (ret) > - goto failed_removal; > + if (ret) { > + reason = "notifier failure"; > + goto failed_removal_isolated; > + } > > pfn = start_pfn; > repeat: > /* start memory hot removal */ > ret = -EINTR; > - if (signal_pending(current)) > - goto failed_removal; > + if (signal_pending(current)) { > + reason = "signal backoff"; > + goto failed_removal_isolated; > + } > > cond_resched(); > lru_add_drain_all(); > @@ -1607,8 +1615,10 @@ static int __ref __offline_pages(unsigned long start_pfn, > * actually in order to make hugetlbfs's object counting consistent. > */ > ret = dissolve_free_huge_pages(start_pfn, end_pfn); > - if (ret) > - goto failed_removal; > + if (ret) { > + reason = "failure to dissolve huge pages"; > + goto failed_removal_isolated; > + } > /* check again */ > offlined_pages = check_pages_isolated(start_pfn, end_pfn); > if (offlined_pages < 0) > @@ -1648,13 +1658,15 @@ static int __ref __offline_pages(unsigned long start_pfn, > mem_hotplug_done(); > return 0; > > +failed_removal_isolated: > + undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); > failed_removal: > - pr_debug("memory offlining [mem %#010llx-%#010llx] failed\n", > + pr_debug("memory offlining [mem %#010llx-%#010llx] failed due to %s\n", > (unsigned long long) start_pfn << PAGE_SHIFT, > - ((unsigned long long) end_pfn << PAGE_SHIFT) - 1); > + ((unsigned long long) end_pfn << PAGE_SHIFT) - 1, > + reason); > memory_notify(MEM_CANCEL_OFFLINE, &arg); > /* pushback to free area */ > - undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE); > mem_hotplug_done(); > return ret; > } > Reviewed-by: Anshuman Khandual