linux-kernel - Re: [PATCH v7 11/14] mm,hwpoison: return 0 if the page is already poisoned in soft-offline

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Date:   Wed, 23 Sep 2020 07:39:10 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     Oscar Salvador <osalvador@...e.de>
CC:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "aris@...vo.org" <aris@...vo.org>,
        "mhocko@...nel.org" <mhocko@...nel.org>,
        "tony.luck@...el.com" <tony.luck@...el.com>,
        "cai@....pw" <cai@....pw>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH v7 11/14] mm,hwpoison: return 0 if the page is already
 poisoned in soft-offline

On Tue, Sep 22, 2020 at 03:56:47PM +0200, Oscar Salvador wrote:
> Currently, there is an inconsistency when calling soft-offline from
> different paths on a page that is already poisoned.
> 
> 1) madvise:
> 
>         madvise_inject_error skips any poisoned page and continues
>         the loop.
>         If that was the only page to madvise, it returns 0.
> 
> 2) /sys/devices/system/memory/:
> 
>         When calling soft_offline_page_store()->soft_offline_page(),
>         we return -EBUSY in case the page is already poisoned.
>         This is inconsistent with a) the above example and b)
>         memory_failure, where we return 0 if the page was poisoned.
> 
> Fix this by dropping the PageHWPoison() check in madvise_inject_error, and
> let soft_offline_page return 0 if it finds the page already poisoned.
> 
> Please, note that this represents a user-api change, since now the return
> error when calling soft_offline_page_store()->soft_offline_page() will be
> different.
> 
> Signed-off-by: Oscar Salvador <osalvador@...e.de>

Acked-by: Naoya Horiguchi <naoya.horiguchi@....com>