linux-kernel - Re: [PATCH 1/9] mm/madvise: use is_memory_failure() from madvise_do

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Message-ID: <0e8c5b99-6b9c-4e10-b33d-42485a943125@lucifer.local>
Date: Tue, 11 Mar 2025 11:27:57 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: SeongJae Park <sj@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        "Liam R. Howlett" <howlett@...il.com>,
        David Hildenbrand <david@...hat.com>,
        Shakeel Butt <shakeel.butt@...ux.dev>,
        Vlastimil Babka <vbabka@...e.cz>, kernel-team@...a.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 1/9] mm/madvise: use is_memory_failure() from
 madvise_do_behavior()

On Mon, Mar 10, 2025 at 10:23:10AM -0700, SeongJae Park wrote:
> To reduce redundant open-coded checks of CONFIG_MEMORY_FAILURE and
> MADV_{HWPOISON,SOFT_OFFLINE} in madvise_[un]lock(), is_memory_failure()
> has introduced.  madvise_do_behavior() is still doing the same

NIT: 'is' introduced.

> open-coded check, though.  Use is_memory_failure() instead.
>
> To avoid build failure on !CONFIG_MEMORY_FAILURE case, implement an
> empty madvise_inject_error() under the config.  Also move the definition
> of is_memory_failure() inside #ifdef CONFIG_MEMORY_FAILURE clause for
> madvise_inject_error() definition, to reduce duplicated ifdef clauses.
>
> Signed-off-by: SeongJae Park <sj@...nel.org>

Good improvement, thanks!

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  mm/madvise.c | 49 +++++++++++++++++++++++++++----------------------
>  1 file changed, 27 insertions(+), 22 deletions(-)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 388dc289b5d1..c3ab1f283b18 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -1392,7 +1392,32 @@ static int madvise_inject_error(int behavior,
>
>  	return 0;
>  }
> -#endif
> +
> +static bool is_memory_failure(int behavior)
> +{
> +	switch (behavior) {
> +	case MADV_HWPOISON:
> +	case MADV_SOFT_OFFLINE:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +#else
> +
> +static int madvise_inject_error(int behavior,
> +		unsigned long start, unsigned long end)
> +{
> +	return 0;
> +}
> +
> +static bool is_memory_failure(int behavior)
> +{
> +	return false;
> +}
> +
> +#endif	/* CONFIG_MEMORY_FAILURE */
>
>  static bool
>  madvise_behavior_valid(int behavior)
> @@ -1569,24 +1594,6 @@ int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
>  }
>  #endif /* CONFIG_ANON_VMA_NAME */
>
> -#ifdef CONFIG_MEMORY_FAILURE
> -static bool is_memory_failure(int behavior)
> -{
> -	switch (behavior) {
> -	case MADV_HWPOISON:
> -	case MADV_SOFT_OFFLINE:
> -		return true;
> -	default:
> -		return false;
> -	}
> -}
> -#else
> -static bool is_memory_failure(int behavior)
> -{
> -	return false;
> -}
> -#endif
> -
>  static int madvise_lock(struct mm_struct *mm, int behavior)
>  {
>  	if (is_memory_failure(behavior))
> @@ -1640,10 +1647,8 @@ static int madvise_do_behavior(struct mm_struct *mm,
>  	unsigned long end;
>  	int error;
>
> -#ifdef CONFIG_MEMORY_FAILURE
> -	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
> +	if (is_memory_failure(behavior))
>  		return madvise_inject_error(behavior, start, start + len_in);
> -#endif
>  	start = untagged_addr_remote(mm, start);
>  	end = start + len;
>
> --
> 2.39.5