Re: [PATCH v6 12/12] mm,hwpoison: double-check page count in __get_any_page()

[Oscar Salvador]

On Thu, Aug 06, 2020 at 06:49:23PM +0000, nao.horiguchi@xxxxxxxxx wrote:
> From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
> 
> Soft offlining could fail with EIO due to the race condition with
> hugepage migration. This issuse became visible due to the change by
> previous patch that makes soft offline handler take page refcount
> by its own.  We have no way to directly pin zero refcount page, and
> the page considered as a zero refcount page could be allocated just
> after the first check.
> 
> This patch adds the second check to find the race and gives us
> chance to handle it more reliably.
> 
> Reported-by: Qian Cai <cai@xxxxxx>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>

Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>

-- 
Oscar Salvador
SUSE L3