Split out the madvise parameters validation logic from do_madvise(), for
easy reuse of the logic from a future change.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/madvise.c | 32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index ae0964bc4d88..9cc31efe875a 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1592,6 +1592,27 @@ static void madvise_unlock(struct mm_struct *mm, int behavior)
 		mmap_read_unlock(mm);
 }
 
+static bool is_valid_madvise(unsigned long start, size_t len_in, int behavior)
+{
+	size_t len;
+
+	if (!madvise_behavior_valid(behavior))
+		return false;
+
+	if (!PAGE_ALIGNED(start))
+		return false;
+	len = PAGE_ALIGN(len_in);
+
+	/* Check to see whether len was rounded up from small -ve to zero */
+	if (len_in && !len)
+		return false;
+
+	if (start + len < start)
+		return false;
+
+	return true;
+}
+
 /*
  * The madvise(2) system call.
  *
@@ -1671,20 +1692,11 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
 	size_t len;
 	struct blk_plug plug;
 
-	if (!madvise_behavior_valid(behavior))
+	if (!is_valid_madvise(start, len_in, behavior))
 		return -EINVAL;
 
-	if (!PAGE_ALIGNED(start))
-		return -EINVAL;
 	len = PAGE_ALIGN(len_in);
-
-	/* Check to see whether len was rounded up from small -ve to zero */
-	if (len_in && !len)
-		return -EINVAL;
-
 	end = start + len;
-	if (end < start)
-		return -EINVAL;
 
 	if (end == start)
 		return 0;
-- 
2.39.5

On Thu, 16 Jan 2025, SeongJae Park wrote:

>Split out the madvise parameters validation logic from do_madvise(), for
>easy reuse of the logic from a future change.
>
>Signed-off-by: SeongJae Park <sj@kernel.org>

Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>

On Thu, Jan 16, 2025 at 05:30:56PM -0800, SeongJae Park wrote:
> Split out the madvise parameters validation logic from do_madvise(), for
> easy reuse of the logic from a future change.
>
> Signed-off-by: SeongJae Park <sj@kernel.org>

Another decent cleanup, regardless of appllication, so:

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

> ---
>  mm/madvise.c | 32 ++++++++++++++++++++++----------
>  1 file changed, 22 insertions(+), 10 deletions(-)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index ae0964bc4d88..9cc31efe875a 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -1592,6 +1592,27 @@ static void madvise_unlock(struct mm_struct *mm, int behavior)
>  		mmap_read_unlock(mm);
>  }
>
> +static bool is_valid_madvise(unsigned long start, size_t len_in, int behavior)
> +{
> +	size_t len;
> +
> +	if (!madvise_behavior_valid(behavior))
> +		return false;
> +
> +	if (!PAGE_ALIGNED(start))
> +		return false;
> +	len = PAGE_ALIGN(len_in);

Kind of a pity to duplicate this, but not exactly a big deal.

> +
> +	/* Check to see whether len was rounded up from small -ve to zero */
> +	if (len_in && !len)
> +		return false;
> +
> +	if (start + len < start)
> +		return false;
> +
> +	return true;
> +}
> +
>  /*
>   * The madvise(2) system call.
>   *
> @@ -1671,20 +1692,11 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
>  	size_t len;
>  	struct blk_plug plug;
>
> -	if (!madvise_behavior_valid(behavior))
> +	if (!is_valid_madvise(start, len_in, behavior))
>  		return -EINVAL;
>
> -	if (!PAGE_ALIGNED(start))
> -		return -EINVAL;
>  	len = PAGE_ALIGN(len_in);
> -
> -	/* Check to see whether len was rounded up from small -ve to zero */
> -	if (len_in && !len)
> -		return -EINVAL;
> -
>  	end = start + len;
> -	if (end < start)
> -		return -EINVAL;
>
>  	if (end == start)
>  		return 0;
> --
> 2.39.5

On Thu, Jan 16, 2025 at 05:30:56PM -0800, SeongJae Park wrote:
> Split out the madvise parameters validation logic from do_madvise(), for
> easy reuse of the logic from a future change.
> 
> Signed-off-by: SeongJae Park <sj@kernel.org>

Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>