From: Michal Hocko <mhocko@kernel.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Reza Arbab <arbab@linux.vnet.ibm.com>,
Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
qiuxishi@huawei.com, Igor Mammedov <imammedo@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early
Date: Wed, 11 Oct 2017 08:51:23 +0200 [thread overview]
Message-ID: <20171011065123.e7jvoftmtso3vcha@dhcp22.suse.cz> (raw)
In-Reply-To: <87infmz9xd.fsf@concordia.ellerman.id.au>
On Wed 11-10-17 13:37:50, Michael Ellerman wrote:
> Michal Hocko <mhocko@kernel.org> writes:
>
> > On Tue 10-10-17 23:05:08, Michael Ellerman wrote:
> >> Michal Hocko <mhocko@kernel.org> writes:
> >>
> >> > From: Michal Hocko <mhocko@suse.com>
> >> >
> >> > Memory offlining can fail just too eagerly under a heavy memory pressure.
> >> >
> >> > [ 5410.336792] page:ffffea22a646bd00 count:255 mapcount:252 mapping:ffff88ff926c9f38 index:0x3
> >> > [ 5410.336809] flags: 0x9855fe40010048(uptodate|active|mappedtodisk)
> >> > [ 5410.336811] page dumped because: isolation failed
> >> > [ 5410.336813] page->mem_cgroup:ffff8801cd662000
> >> > [ 5420.655030] memory offlining [mem 0x18b580000000-0x18b5ffffffff] failed
> >> >
> >> > Isolation has failed here because the page is not on LRU. Most probably
> >> > because it was on the pcp LRU cache or it has been removed from the LRU
> >> > already but it hasn't been freed yet. In both cases the page doesn't look
> >> > non-migrable so retrying more makes sense.
> >>
> >> This breaks offline for me.
> >>
> >> Prior to this commit:
> >> /sys/devices/system/memory/memory0# time echo 0 > online
> >> -bash: echo: write error: Device or resource busy
> >>
> >> real 0m0.001s
> >> user 0m0.000s
> >> sys 0m0.001s
> >>
> >> After:
> >> /sys/devices/system/memory/memory0# time echo 0 > online
> >> -bash: echo: write error: Device or resource busy
> >>
> >> real 2m0.009s
> >> user 0m0.000s
> >> sys 1m25.035s
> >>
> >>
> >> There's no way that block can be removed, it contains the kernel text,
> >> so it should instantly fail - which it used to.
> >
> > OK, that means that start_isolate_page_range should have failed but it
> > hasn't for some reason. I strongly suspect has_unmovable_pages is doing
> > something wrong. Is the kernel text marked somehow? E.g. PageReserved?
>
> I'm not sure how the text is marked, will have to dig into that.
>
> > In other words, does the diff below helps?
>
> No that doesn't help.
This is really strange! As you write in other email the page is
reserved. That means that some of the earlier checks
if (zone_idx(zone) == ZONE_MOVABLE)
return false;
mt = get_pageblock_migratetype(page);
if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt))
return false;
has bailed out early. I would be quite surprised if the kernel text was
sitting in the zone movable. The migrate type check is more fishy
AFAICS. I can imagine that the kernel text can share the movable or CMA
mt block. I am not really familiar with this function but it looks
suspicious. So does it help to remove this check?
---
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3badcedf96a7..5b4d85ae445c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7355,9 +7355,6 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
*/
if (zone_idx(zone) == ZONE_MOVABLE)
return false;
- mt = get_pageblock_migratetype(page);
- if (mt == MIGRATE_MOVABLE || is_migrate_cma(mt))
- return false;
pfn = page_to_pfn(page);
for (found = 0, iter = 0; iter < pageblock_nr_pages; iter++) {
@@ -7368,6 +7365,9 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
page = pfn_to_page(check);
+ if (PageReserved(page))
+ return true;
+
/*
* Hugepages are not in LRU lists, but they're movable.
* We need not scan over tail pages bacause we don't
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-10-11 6:51 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-18 7:08 [PATCH v2 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko
2017-09-18 7:08 ` [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early Michal Hocko
2017-10-10 12:05 ` Michael Ellerman
2017-10-10 12:27 ` Michal Hocko
2017-10-11 2:37 ` Michael Ellerman
2017-10-11 5:19 ` Michael Ellerman
2017-10-11 14:05 ` Anshuman Khandual
2017-10-11 14:16 ` Michal Hocko
2017-10-11 6:51 ` Michal Hocko [this message]
2017-10-11 8:04 ` Vlastimil Babka
2017-10-11 8:13 ` Michal Hocko
2017-10-11 11:17 ` Vlastimil Babka
2017-10-11 11:24 ` Michal Hocko
2017-10-13 11:42 ` Michael Ellerman
2017-10-13 11:58 ` Michal Hocko
2017-10-13 12:00 ` [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages Michal Hocko
2017-10-13 12:00 ` [PATCH 2/2] mm, page_alloc: fail has_unmovable_pages when seeing reserved pages Michal Hocko
2017-10-13 12:04 ` Vlastimil Babka
2017-10-13 12:07 ` Michal Hocko
2017-10-17 13:03 ` Vlastimil Babka
2017-10-17 11:41 ` [PATCH 1/2] mm: drop migrate type checks from has_unmovable_pages Michael Ellerman
2017-10-17 12:03 ` Michal Hocko
2017-10-17 13:02 ` Vlastimil Babka
2017-10-19 2:51 ` Joonsoo Kim
2017-10-19 7:15 ` Michal Hocko
2017-10-19 7:33 ` Joonsoo Kim
2017-10-19 8:20 ` Michal Hocko
2017-10-19 12:21 ` Michal Hocko
2017-10-20 2:13 ` Joonsoo Kim
2017-10-20 5:59 ` Michal Hocko
2017-10-20 6:50 ` Joonsoo Kim
2017-10-20 7:02 ` Michal Hocko
2017-10-23 5:23 ` Joonsoo Kim
2017-10-23 8:10 ` Michal Hocko
2017-10-24 4:44 ` Joonsoo Kim
2017-10-24 7:44 ` Michal Hocko
2017-10-24 8:12 ` Vlastimil Babka
2017-10-24 12:25 ` Michal Hocko
2017-10-26 2:47 ` Joonsoo Kim
2017-10-26 7:41 ` Michal Hocko
2017-10-20 7:22 ` Xishi Qiu
2017-10-20 8:17 ` Michal Hocko
2017-10-23 5:26 ` Joonsoo Kim
2017-10-26 13:04 ` Vlastimil Babka
2017-10-26 13:59 ` Michal Hocko
2017-09-18 7:08 ` [PATCH 2/2] mm, memory_hotplug: remove timeout from __offline_memory Michal Hocko
-- strict thread matches above, loose matches on Subject: below --
2017-09-04 8:21 [PATCH 0/2] mm, memory_hotplug: redefine memory offline retry logic Michal Hocko
2017-09-04 8:21 ` [PATCH 1/2] mm, memory_hotplug: do not fail offlining too early Michal Hocko
2017-09-05 6:29 ` Anshuman Khandual
2017-09-05 7:13 ` Michal Hocko
2017-09-08 17:26 ` Vlastimil Babka
2017-09-11 8:17 ` Michal Hocko
2017-09-13 11:41 ` Vlastimil Babka
2017-09-13 12:10 ` Michal Hocko
2017-09-13 12:14 ` Michal Hocko
2017-09-13 12:19 ` Vlastimil Babka
2017-09-13 12:32 ` Michal Hocko
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