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Date:   Tue, 11 Aug 2020 13:39:24 -0400
From:   Qian Cai <cai@lca.pw>
To:     HORIGUCHI =?utf-8?B?TkFPWUEo5aCA5Y+j44CA55u05LmfKQ==?= 
        <naoya.horiguchi@nec.com>
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Subject: Re: [PATCH v6 00/12] HWPOISON: soft offline rework
Message-ID: <20200811173923.GA39857@lca.pw>
References: <20200806184923.7007-1-nao.horiguchi@gmail.com>
 <20200810152254.GC5307@lca.pw>
 <20200811031139.GA7145@hori.linux.bs1.fc.nec.co.jp>
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On Tue, Aug 11, 2020 at 03:11:40AM +0000, HORIGUCHI NAOYA(堀口 直也) wrote:
> I'm still not sure why the test succeeded by reverting these because
> current mainline kernel provides similar mechanism to prevent reuse of
> soft offlined page. So this success seems to me something suspicious.
> 
> To investigate more, I want to have additional info about the page states
> of the relevant pages after soft offlining.  Could you collect it by the
> following steps?
> 
>   - modify random.c not to run hotplug_memory() in migrate_huge_hotplug_memory(),
>   - compile it and run "./random 1" once,
>   - to collect page state with hwpoisoned pages, run "./page-types -Nlr -b hwpoison",
>     where page-types is available under tools/vm in kernel source tree.
>   - choose a few pfns of soft offlined pages from kernel message
>     "Soft offlining pfn ...", and run "./page-types -Nlr -a <pfn>".

# ./page-types -Nlr -b hwpoison
offset	len	flags
99a000	1	__________B________X_______________________
99c000	1	__________B________X_______________________
99e000	1	__________B________X_______________________
9a0000	1	__________B________X_______________________
ba6000	1	__________B________X_______________________
baa000	1	__________B________X_______________________

Every single one of pfns was like this,

# ./page-types -Nlr -a 0x99a000
offset	len	flags
99a000	1	__________B________X_______________________

# ./page-types -Nlr -a 0x99e000
offset	len	flags
99e000	1	__________B________X_______________________

# ./page-types -Nlr -a 0x99c000
offset	len	flags
99c000	1	__________B________X_______________________