From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ot1-f72.google.com (mail-ot1-f72.google.com [209.85.210.72]) by kanga.kvack.org (Postfix) with ESMTP id 4A3E76B059C for ; Thu, 8 Nov 2018 03:19:59 -0500 (EST) Received: by mail-ot1-f72.google.com with SMTP id p29so5577951ote.3 for ; Thu, 08 Nov 2018 00:19:59 -0800 (PST) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id z45si1550392otz.301.2018.11.08.00.19.57 for ; Thu, 08 Nov 2018 00:19:58 -0800 (PST) Subject: Re: [RFC PATCH 5/5] mm, memory_hotplug: be more verbose for memory offline failures References: <20181107101830.17405-1-mhocko@kernel.org> <20181107101830.17405-6-mhocko@kernel.org> <20181108081231.GN27423@dhcp22.suse.cz> From: Anshuman Khandual Message-ID: <807cde15-a083-e8ae-4bd0-5f83f4b02b6a@arm.com> Date: Thu, 8 Nov 2018 13:49:52 +0530 MIME-Version: 1.0 In-Reply-To: <20181108081231.GN27423@dhcp22.suse.cz> 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: linux-mm@kvack.org, Oscar Salvador , Baoquan He , LKML On 11/08/2018 01:42 PM, Michal Hocko wrote: > On Thu 08-11-18 12:46:47, Anshuman Khandual wrote: >> >> >> On 11/07/2018 03:48 PM, Michal Hocko wrote: > [...] >>> @@ -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 ", >>> + page_to_pfn(page), ret); >> >> Seems like pr_warn() needs to have %d in here to print 'ret'. > > Dohh. Rebase hickup. You are right ret:%d got lost on the way. > >> Though >> dumping return code from migrate_pages() makes sense, wondering if >> it is required for each and every page which failed to migrate here >> or just one instance is enough. > > Does it matter enough to special case one printk? I just imagined how a bunch of prints will look like when multiple pages failed to migrate probably for the same reason. But I guess its okay. > >>> + dump_page(page, NULL); >>> + } >> >> s/NULL/failed to migrate/ for dump_page(). > > Yes, makes sense. > >> >>> putback_movable_pages(&source); >>> + } >>> } >>> out: >>> return ret; >>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>> index a919ba5cb3c8..23267767bf98 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), "has_unmovable_pages"); >> >> s/has_unmovable_pages/is unmovable/ > > OK > >> If we eally care about the function name, then dump_page() should be >> followed by dump_stack() like the case in some other instances. >> >>> return true; >> >> This will be dumped from HugeTLB and CMA allocation paths as well through >> alloc_contig_range(). But it should be okay as those occurrences should be >> rare and dumping page state then will also help. > > yes > > Thanks and here is the incremental fix: > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index bf214beccda3..820397e18e59 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1411,9 +1411,9 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > MIGRATE_SYNC, MR_MEMORY_HOTPLUG); > if (ret) { > list_for_each_entry(page, &source, lru) { > - pr_warn("migrating pfn %lx failed ", > + pr_warn("migrating pfn %lx failed ret:%d ", > page_to_pfn(page), ret); > - dump_page(page, NULL); > + dump_page(page, "migration failure"); > } > putback_movable_pages(&source); > } > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 23267767bf98..ec2c7916dc2d 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7845,7 +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), "has_unmovable_pages"); > + dump_page(pfn_to_page(pfn+iter), "unmovable page"); > return true; > } It looks good.