From: David Hildenbrand <david@redhat.com>
To: Michal Hocko <mhocko@kernel.org>,
Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: akpm@linux-foundation.org, osalvador@suse.de,
dan.j.williams@intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/spase: never partially remove memmap for early section
Date: Wed, 24 Jun 2020 10:04:07 +0200 [thread overview]
Message-ID: <0b8a214e-8f7e-7137-55af-7dd917c3785b@redhat.com> (raw)
In-Reply-To: <57d8a558-dcb3-b318-8e38-6c016b050414@redhat.com>
On 24.06.20 09:48, David Hildenbrand wrote:
> On 23.06.20 17:18, Michal Hocko wrote:
>> On Tue 23-06-20 17:42:58, Wei Yang wrote:
>>> For early sections, we assumes its memmap will never be partially
>>> removed. But current behavior breaks this.
>>>
>>> Let's correct it.
>>>
>>> Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug")
>>> Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
>>
>> Can a user trigger this or is this a theoretical bug?
>
> I tried to reproduce it, but somehow I get unexpected behavior.
> With a hacked QEMU I can get
>
> $ cat /proc/iomem
> [...]
> 100000000-143ffffff : System RAM
> 144000000-343dfffff : Persistent Memory
> 144000000-1441fffff : namespace0.0
> 144200000-144ffffff : dax0.0
>
> After
> $ ndctl create-namespace --force --reconfig=namespace0.0 --mode=devdax --size=16M
>
> I get
>
> $ cat /proc/iomem
> [...]
> 100000000-143ffffff : System RAM
> 144000000-343dfffff : Persistent Memory
> 144000000-1441fffff : namespace0.0
> 144200000-144ffffff : dax0.0
>
> I can trigger remove+re-add via
> $ ndctl create-namespace --force --reconfig=namespace0.0 --mode=devdax --size=16M
>
> So we clearly have an overlap between System RAM and dax0.0 within a section.
> However, I never get early_section() to trigger in
> section_activate()/section_deactivate() ? That's unexpected
... booting the correct kernel I can see the printk's I added ... I'll
continue to poke it with a stick.
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2020-06-24 8:04 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 9:42 Wei Yang
2020-06-23 12:44 ` David Hildenbrand
2020-06-23 13:02 ` Wei Yang
2020-06-23 13:16 ` David Hildenbrand
2020-06-23 15:18 ` Michal Hocko
2020-06-23 21:48 ` Wei Yang
2020-06-24 6:13 ` Wei Yang
2020-06-24 16:10 ` Dan Williams
2020-06-24 22:05 ` Wei Yang
2020-06-24 22:20 ` Dan Williams
2020-06-24 22:44 ` Wei Yang
2020-06-24 23:47 ` Dan Williams
2020-06-25 5:53 ` David Hildenbrand
2020-06-25 19:46 ` Dan Williams
2020-06-25 22:29 ` Wei Yang
[not found] ` <20200629083411.GA38188@L-31X9LVDL-1304.local>
2020-06-29 22:13 ` Dan Williams
2020-06-29 22:58 ` Wei Yang
2020-06-30 7:16 ` David Hildenbrand
2020-06-25 22:39 ` Wei Yang
2020-06-26 4:59 ` David Hildenbrand
2020-06-24 7:48 ` David Hildenbrand
2020-06-24 8:04 ` David Hildenbrand [this message]
2020-06-24 8:13 ` Wei Yang
2020-06-24 8:41 ` David Hildenbrand
2020-06-24 8:50 ` Michal Hocko
2020-06-24 22:27 ` Wei Yang
2020-06-24 0:21 ` Dan Williams
2020-06-24 1:11 ` Wei Yang
2020-06-24 1:47 ` Baoquan He
2020-06-24 2:14 ` Baoquan He
2020-06-24 3:46 ` Wei Yang
2020-06-24 3:52 ` Baoquan He
2020-06-24 3:56 ` Wei Yang
2020-06-24 8:51 ` David Hildenbrand
2020-06-24 22:08 ` Wei Yang
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