From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-f198.google.com (mail-oi1-f198.google.com [209.85.167.198]) by kanga.kvack.org (Postfix) with ESMTP id 4C9E16B096B for ; Fri, 16 Nov 2018 07:07:51 -0500 (EST) Received: by mail-oi1-f198.google.com with SMTP id e141so4151433oig.11 for ; Fri, 16 Nov 2018 04:07:51 -0800 (PST) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id u9si13097469otb.172.2018.11.16.04.07.50 for ; Fri, 16 Nov 2018 04:07:50 -0800 (PST) Subject: Re: [PATCH 5/5] mm, memory_hotplug: be more verbose for memory offline failures References: <20181116083020.20260-1-mhocko@kernel.org> <20181116083020.20260-6-mhocko@kernel.org> From: Anshuman Khandual Message-ID: <68bb826c-104f-3c53-28fe-5e9a55df1d1e@arm.com> Date: Fri, 16 Nov 2018 17:37:45 +0530 MIME-Version: 1.0 In-Reply-To: <20181116083020.20260-6-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 > > There is only very limited information printed when the memory offlining > fails: > [ 1984.506184] rac1 kernel: memory offlining [mem 0x82600000000-0x8267fffffff] failed due to signal backoff > > This tells us that the failure is triggered by the userspace > intervention but it doesn't tell us much more about the underlying > reason. It might be that the page migration failes repeatedly and the > userspace timeout expires and send a signal or it might be some of the > earlier steps (isolation, memory notifier) takes too long. > > If the migration failes then it would be really helpful to see which > page that and its state. The same applies to the isolation phase. If we > fail to isolate a page from the allocator then knowing the state of the > page would be helpful as well. > > Dump the page state that fails to get isolated or migrated. This will > tell us more about the failure and what to focus on during debugging. > > Signed-off-by: Michal Hocko > --- > mm/memory_hotplug.c | 12 ++++++++---- > mm/page_alloc.c | 1 + > 2 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 88d50e74e3fe..c82193db4be6 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1388,10 +1388,8 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > page_is_file_cache(page)); > > } else { > -#ifdef CONFIG_DEBUG_VM > - pr_alert("failed to isolate pfn %lx\n", pfn); > + pr_warn("failed to isolate pfn %lx\n", pfn); > dump_page(page, "isolation failed"); > -#endif > put_page(page); > /* Because we don't have big zone->lock. we should > check this again here. */ > @@ -1411,8 +1409,14 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > /* Allocate a new page from the nearest neighbor node */ > ret = migrate_pages(&source, new_node_page, NULL, 0, > MIGRATE_SYNC, MR_MEMORY_HOTPLUG); > - if (ret) > + if (ret) { > + list_for_each_entry(page, &source, lru) { > + pr_warn("migrating pfn %lx failed ret:%d ", > + page_to_pfn(page), ret); > + dump_page(page, "migration failure"); > + } > putback_movable_pages(&source); > + } > } > out: > return ret; > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index a919ba5cb3c8..ec2c7916dc2d 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7845,6 +7845,7 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count, > return false; > unmovable: > WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE); > + dump_page(pfn_to_page(pfn+iter), "unmovable page"); > return true; > } This seems to have fixed the previous build problem because of the migrate_pages() return code. Otherwise looks good. Reviewed-by: Anshuman Khandual