From: Michael Ellerman <mpe@ellerman.id.au>
To: Michal Hocko <mhocko@kernel.org>
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 16:19:05 +1100 [thread overview]
Message-ID: <87a80yz2gm.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <87infmz9xd.fsf@concordia.ellerman.id.au>
Michael Ellerman <mpe@ellerman.id.au> writes:
> 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.
Yeah it's reserved:
$ grep __init_begin /proc/kallsyms
c000000000d70000 T __init_begin
$ ./page-types -r -a 0x0,0xd7
flags page-count MB symbolic-flags long-symbolic-flags
0x0000000100000000 215 13 __________________________r_______________ reserved
total 215 13
I added some printks, we're getting EBUSY from do_migrate_range(pfn, end_pfn).
So we seem to just have an infinite loop:
repeat:
/* start memory hot removal */
ret = -EINTR;
if (signal_pending(current))
goto failed_removal;
cond_resched();
lru_add_drain_all_cpuslocked();
drain_all_pages(zone);
pfn = scan_movable_pages(start_pfn, end_pfn);
if (pfn) { /* We have movable pages */
ret = do_migrate_range(pfn, end_pfn);
printk_ratelimited("memory-hotplug: migrate range returned %ld\n", ret);
goto repeat;
}
eg:
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
__offline_pages: 354031 callbacks suppressed
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
memory-hotplug: migrate range returned -16
__offline_pages: 355794 callbacks suppressed
cheers
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next prev parent reply other threads:[~2017-10-11 5:19 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 [this message]
2017-10-11 14:05 ` Anshuman Khandual
2017-10-11 14:16 ` Michal Hocko
2017-10-11 6:51 ` Michal Hocko
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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