linux-kernel - Re: [PATCH v2 1/2] mm: soft-offline: return -EBUSY if set_hwpoison_free_buddy

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Message-ID: <20190611005715.GB5187@hori.linux.bs1.fc.nec.co.jp>
Date:   Tue, 11 Jun 2019 00:57:08 +0000
From:   Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:     Mike Kravetz <mike.kravetz@...cle.com>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        "xishi.qiuxishi@...baba-inc.com" <xishi.qiuxishi@...baba-inc.com>,
        "Chen, Jerry T" <jerry.t.chen@...el.com>,
        "Zhuo, Qiuxu" <qiuxu.zhuo@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] mm: soft-offline: return -EBUSY if
 set_hwpoison_free_buddy_page() fails

On Mon, Jun 10, 2019 at 05:19:45PM -0700, Mike Kravetz wrote:
> On 6/10/19 1:18 AM, Naoya Horiguchi wrote:
> > The pass/fail of soft offline should be judged by checking whether the
> > raw error page was finally contained or not (i.e. the result of
> > set_hwpoison_free_buddy_page()), but current code do not work like that.
> > So this patch is suggesting to fix it.
> > 
> > Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> > Fixes: 6bc9b56433b76 ("mm: fix race on soft-offlining")
> > Cc: <stable@...r.kernel.org> # v4.19+
> 
> Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>

Thank you, Mike.

> 
> To follow-up on Andrew's comment/question about user visible effects.  Without
> this fix, there are cases where madvise(MADV_SOFT_OFFLINE) may not offline the
> original page and will not return an error.

Yes, that's right.

>  Are there any other visible
> effects?

I can't think of other ones.

- Naoya