linux-kernel - Re: [PATCH v2 1/2] mm: Uncharge poisoned pages

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Message-ID: <20170427143721.GK4706@dhcp22.suse.cz>
Date:   Thu, 27 Apr 2017 16:37:21 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Laurent Dufour <ldufour@...ux.vnet.ibm.com>
Cc:     Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org
Subject: Re: [PATCH v2 1/2] mm: Uncharge poisoned pages

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?
-- 
Michal Hocko
SUSE Labs