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From: Michal Hocko <mhocko@kernel.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, Oscar Salvador <OSalvador@suse.com>,
	Baoquan He <bhe@redhat.com>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 5/5] mm, memory_hotplug: be more verbose for memory offline failures
Date: Thu, 8 Nov 2018 09:12:31 +0100	[thread overview]
Message-ID: <20181108081231.GN27423@dhcp22.suse.cz> (raw)
In-Reply-To: <b23ebcb3-e4f1-be78-bd5f-84c685979ab7@arm.com>

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?

> > +				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;
 }
 
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2018-11-08  8:12 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-07 10:18 [RFC PATCH 0/5] mm, memory_hotplug: improve memory offlining failures debugging Michal Hocko
2018-11-07 10:18 ` Michal Hocko
2018-11-07 10:18 ` [RFC PATCH 1/5] mm: print more information about mapping in __dump_page Michal Hocko
2018-11-07 10:18   ` Michal Hocko
2018-11-24  0:04   ` Andrew Morton
2018-11-24  0:04     ` Andrew Morton
2018-11-25  8:10     ` Michal Hocko
2018-11-07 10:18 ` [RFC PATCH 2/5] mm: lower the printk loglevel for __dump_page messages Michal Hocko
2018-11-07 10:18   ` Michal Hocko
2018-11-16  0:56   ` Baoquan He
2018-12-12 14:25   ` Michal Hocko
2018-12-12 14:34     ` Michal Hocko
2018-11-07 10:18 ` [RFC PATCH 3/5] mm, memory_hotplug: drop pointless block alignment checks from __offline_pages Michal Hocko
2018-11-07 10:18   ` Michal Hocko
2018-11-07 10:18 ` [RFC PATCH 4/5] mm, memory_hotplug: print reason for the offlining failure Michal Hocko
2018-11-07 10:18   ` Michal Hocko
2018-11-07 22:04   ` Andrew Morton
2018-11-07 22:04     ` Andrew Morton
2018-11-08  8:01     ` Michal Hocko
2018-11-13  8:02     ` Michal Hocko
2018-11-08  6:23   ` Anshuman Khandual
2018-11-08  7:59     ` Michal Hocko
2018-11-07 10:18 ` [RFC PATCH 5/5] mm, memory_hotplug: be more verbose for memory offline failures Michal Hocko
2018-11-07 10:18   ` Michal Hocko
2018-11-08  7:16   ` Anshuman Khandual
2018-11-08  8:12     ` Michal Hocko [this message]
2018-11-08  8:19       ` Anshuman Khandual
2018-11-13  8:03       ` Michal Hocko
2018-11-16  0:07   ` Andrew Morton
2018-11-16  0:07     ` Andrew Morton
2018-11-16  7:21     ` Michal Hocko
2018-11-16  7:21       ` Michal Hocko

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