linux-kernel - Re: [PATCH v4 3/7] mm,hwpoison: Try to narrow window race for free pages

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Message-ID: <20200918192724.GD18315@cathedrallabs.org>
Date:   Fri, 18 Sep 2020 15:27:24 -0400
From:   Aristeu Rozanski <aris@...vo.org>
To:     Oscar Salvador <osalvador@...e.de>
Cc:     akpm@...ux-foundation.org, naoya.horiguchi@....com,
        mhocko@...nel.org, tony.luck@...el.com, cai@....pw,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v4 3/7] mm,hwpoison: Try to narrow window race for free
 pages

On Thu, Sep 17, 2020 at 10:10:45AM +0200, Oscar Salvador wrote:
> Aristeu Rozanski reported that a customer test case started
> to report -EBUSY after the hwpoison report patchset.
> 
> There is a race window between spotting a free page and taking it off
> its buddy freelist, so it might be that by the time we try to take it off,
> the page has been already allocated.
> 
> This patch tries to handle such race window by trying to handle the new
> type of page again if the page was allocated under us.
> 
> After this patch, Aristeu said the test cases work properly.
> 
> Signed-off-by: Oscar Salvador <osalvador@...e.de>
> Reported-by: Aristeu Rozanski <aris@...vo.org>

Tested-by: Aristeu Rozanski <aris@...vo.org>

-- 
Aristeu