Re: [PATCH v8 2/3] mm/hwpoison: put page in already hwpoisoned case with MF_COUNT_INCREASED

[Miaohe Lin <linmiaohe@huawei.com>]

On 2022/4/8 21:53, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@nec.com>
> 
> In already hwpoisoned case, memory_failure() is supposed to return with
> releasing the page refcount taken for error handling. But currently the
> refcount is not released when called with MF_COUNT_INCREASED, which
> makes page refcount inconsistent.  This should be rare and non-critical,
> but it might be inconvenient in testing (unpoison doesn't work).

IMHO, this issue will lead to memoryleak as page isn't freed even owner process
is killed. So we might need a Fixes tag?

Anyway, this patch looks good to me. Thanks!
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

> 
> Suggested-by: Miaohe Lin <linmiaohe@huawei.com>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
> ---
>  mm/memory-failure.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 2020944398c9..b2e32cdc3823 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1811,6 +1811,8 @@ int memory_failure(unsigned long pfn, int flags)
>  		res = -EHWPOISON;
>  		if (flags & MF_ACTION_REQUIRED)
>  			res = kill_accessing_process(current, pfn, flags);
> +		if (flags & MF_COUNT_INCREASED)
> +			put_page(p);
>  		goto unlock_mutex;
>  	}
>  
>