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From: Andi Kleen <andi@firstfloor.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	akpm@linux-foundation.org
Subject: Re: [PATCH v2 1/2] mm: Uncharge poisoned pages
Date: Thu, 27 Apr 2017 13:51:23 -0700	[thread overview]
Message-ID: <87pofxk20k.fsf@firstfloor.org> (raw)
In-Reply-To: <20170427143721.GK4706@dhcp22.suse.cz> (Michal Hocko's message of "Thu, 27 Apr 2017 16:37:21 +0200")

Michal Hocko <mhocko@kernel.org> writes:

> On Tue 25-04-17 16:27:51, Laurent Dufour wrote:
>> When page are poisoned, they should be uncharged from the root memory
>> cgroup.
>> 
>> This is required to avoid a BUG raised when the page is onlined back:
>> BUG: Bad page state in process mem-on-off-test  pfn:7ae3b
>> page:f000000001eb8ec0 count:0 mapcount:0 mapping:          (null)
>> index:0x1
>> flags: 0x3ffff800200000(hwpoison)
>
> My knowledge of memory poisoning is very rudimentary but aren't those
> pages supposed to leak and never come back? In other words isn't the
> hoplug code broken because it should leave them alone?

Yes that would be the right interpretation. If it was really offlined
due to a hardware error the memory will be poisoned and any access
could cause a machine check.

hwpoison has an own "unpoison" option (only used for debugging), which
I think handles this.

-Andi

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  reply	other threads:[~2017-04-27 20:51 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-25 14:27 [PATCH v2 0/2] BUG raised when onlining HWPoisoned page Laurent Dufour
2017-04-25 14:27 ` [PATCH v2 1/2] mm: Uncharge poisoned pages Laurent Dufour
2017-04-25 23:48   ` Naoya Horiguchi
2017-04-26  1:54   ` Balbir Singh
2017-04-26  2:34     ` Naoya Horiguchi
2017-04-26  3:45       ` Balbir Singh
2017-04-26  4:46         ` Naoya Horiguchi
2017-04-26  8:59           ` Balbir Singh
2017-04-28  9:32             ` Laurent Dufour
2017-04-27 14:37   ` Michal Hocko
2017-04-27 20:51     ` Andi Kleen [this message]
2017-04-28  6:07       ` Michal Hocko
2017-04-28  7:31         ` Michal Hocko
2017-04-28  9:17           ` Laurent Dufour
2017-04-28 13:48             ` Michal Hocko
2017-05-02 14:59               ` Laurent Dufour
2017-05-02 18:55                 ` Michal Hocko
2017-05-03 11:34                   ` Laurent Dufour
2017-05-04  1:21                   ` Balbir Singh
2017-05-08 10:42                     ` Laurent Dufour
2017-05-09  1:41                       ` Balbir Singh
2017-05-08  2:58                   ` Naoya Horiguchi
2017-05-09  9:18                     ` Michal Hocko
2017-05-09 22:59                       ` Naoya Horiguchi
2017-04-25 14:27 ` [PATCH v2 2/2] mm: skip HWPoisoned pages when onlining pages Laurent Dufour
2017-04-26  2:10   ` Balbir Singh
2017-04-26  3:13     ` Naoya Horiguchi
2017-04-28  2:51       ` Balbir Singh
2017-04-28  6:30       ` Michal Hocko
2017-04-28  6:50         ` Michal Hocko
2017-04-28  6:51           ` Michal Hocko
2017-05-10  7:41             ` Michal Hocko
2018-01-17 23:03         ` Andrew Morton
2018-01-23 18:15           ` Laurent Dufour

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