Re: [PATCH -next 1/1] mm/memory-failure.c: Cleanup in unpoison_memory

[HORIGUCHI NAOYA(堀口 直也)]

On Fri, Nov 25, 2022 at 02:54:44PM +0800, Wupeng Ma wrote:
> From: Ma Wupeng <mawupeng1@xxxxxxxxxx>
> 
> If freeit it true, the value of ret must be zero, there is no need to
> check the value of freeit after label unlock_mutex.
> 
> We can drop variable freeit to do this cleanup.
> 
> Signed-off-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>

Hi Wupeng,

> ---
>  mm/memory-failure.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 2e62940c7bae..c77a9e37e27e 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -2338,7 +2338,6 @@ int unpoison_memory(unsigned long pfn)
>  	struct page *page;
>  	struct page *p;
>  	int ret = -EBUSY;
> -	int freeit = 0;
>  	unsigned long count = 1;
>  	bool huge = false;
>  	static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
> @@ -2413,10 +2412,9 @@ int unpoison_memory(unsigned long pfn)
>  				goto unlock_mutex;
>  			}
>  		}
> -		freeit = !!TestClearPageHWPoison(p);
>  
>  		put_page(page);
> -		if (freeit) {
> +		if (TestClearPageHWPoison(p)) {

This reorders put_page() and TestClearPageHWPoison(), but when we run
into this else block, the target page or hugepage should have refcount > 1,
so it does not cause any behavioral change.  So I'm fine with it.

Looks good to me. Thank you for the patch.

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

>  			put_page(page);
>  			ret = 0;
>  		}
> @@ -2424,7 +2422,7 @@ int unpoison_memory(unsigned long pfn)
>  
>  unlock_mutex:
>  	mutex_unlock(&mf_mutex);
> -	if (!ret || freeit) {
> +	if (!ret) {
>  		if (!huge)
>  			num_poisoned_pages_sub(pfn, 1);
>  		unpoison_pr_info("Unpoison: Software-unpoisoned page %#lx\n",
> -- 
> 2.25.1