Split out the madvise behavior-dependent mmap_lock operations from
do_madvise(), for easier reuse of the logic in an upcoming change.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/madvise.c | 45 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 49f3a75046f6..ae0964bc4d88 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1565,6 +1565,33 @@ int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
 				 madvise_vma_anon_name);
 }
 #endif /* CONFIG_ANON_VMA_NAME */
+
+static int madvise_lock(struct mm_struct *mm, int behavior)
+{
+
+#ifdef CONFIG_MEMORY_FAILURE
+	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
+		return 0;
+#endif
+
+	if (madvise_need_mmap_write(behavior)) {
+		if (mmap_write_lock_killable(mm))
+			return -EINTR;
+	} else {
+		mmap_read_lock(mm);
+	}
+	return 0;
+
+}
+
+static void madvise_unlock(struct mm_struct *mm, int behavior)
+{
+	if (madvise_need_mmap_write(behavior))
+		mmap_write_unlock(mm);
+	else
+		mmap_read_unlock(mm);
+}
+
 /*
  * The madvise(2) system call.
  *
@@ -1641,7 +1668,6 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
 {
 	unsigned long end;
 	int error;
-	int write;
 	size_t len;
 	struct blk_plug plug;
 
@@ -1663,19 +1689,15 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
 	if (end == start)
 		return 0;
 
+	error = madvise_lock(mm, behavior);
+	if (error)
+		return error;
+
 #ifdef CONFIG_MEMORY_FAILURE
 	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
 		return madvise_inject_error(behavior, start, start + len_in);
 #endif
 
-	write = madvise_need_mmap_write(behavior);
-	if (write) {
-		if (mmap_write_lock_killable(mm))
-			return -EINTR;
-	} else {
-		mmap_read_lock(mm);
-	}
-
 	start = untagged_addr_remote(mm, start);
 	end = start + len;
 
@@ -1692,10 +1714,7 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
 	}
 	blk_finish_plug(&plug);
 
-	if (write)
-		mmap_write_unlock(mm);
-	else
-		mmap_read_unlock(mm);
+	madvise_unlock(mm, behavior);
 
 	return error;
 }
-- 
2.39.5

On Thu, Jan 16, 2025 at 05:30:55PM -0800, SeongJae Park wrote:
> Split out the madvise behavior-dependent mmap_lock operations from
> do_madvise(), for easier reuse of the logic in an upcoming change.
>
> Signed-off-by: SeongJae Park <sj@kernel.org>

Looks good to me, a decent cleanup regardless of application.

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

> ---
>  mm/madvise.c | 45 ++++++++++++++++++++++++++++++++-------------
>  1 file changed, 32 insertions(+), 13 deletions(-)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 49f3a75046f6..ae0964bc4d88 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -1565,6 +1565,33 @@ int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
>  				 madvise_vma_anon_name);
>  }
>  #endif /* CONFIG_ANON_VMA_NAME */
> +
> +static int madvise_lock(struct mm_struct *mm, int behavior)
> +{
> +
> +#ifdef CONFIG_MEMORY_FAILURE
> +	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
> +		return 0;
> +#endif
> +
> +	if (madvise_need_mmap_write(behavior)) {
> +		if (mmap_write_lock_killable(mm))
> +			return -EINTR;
> +	} else {
> +		mmap_read_lock(mm);
> +	}
> +	return 0;
> +
> +}
> +
> +static void madvise_unlock(struct mm_struct *mm, int behavior)
> +{
> +	if (madvise_need_mmap_write(behavior))
> +		mmap_write_unlock(mm);
> +	else
> +		mmap_read_unlock(mm);
> +}
> +
>  /*
>   * The madvise(2) system call.
>   *
> @@ -1641,7 +1668,6 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
>  {
>  	unsigned long end;
>  	int error;
> -	int write;
>  	size_t len;
>  	struct blk_plug plug;
>
> @@ -1663,19 +1689,15 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
>  	if (end == start)
>  		return 0;
>
> +	error = madvise_lock(mm, behavior);
> +	if (error)
> +		return error;
> +
>  #ifdef CONFIG_MEMORY_FAILURE
>  	if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
>  		return madvise_inject_error(behavior, start, start + len_in);
>  #endif
>
> -	write = madvise_need_mmap_write(behavior);
> -	if (write) {
> -		if (mmap_write_lock_killable(mm))
> -			return -EINTR;
> -	} else {
> -		mmap_read_lock(mm);
> -	}
> -
>  	start = untagged_addr_remote(mm, start);
>  	end = start + len;
>
> @@ -1692,10 +1714,7 @@ int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int beh
>  	}
>  	blk_finish_plug(&plug);
>
> -	if (write)
> -		mmap_write_unlock(mm);
> -	else
> -		mmap_read_unlock(mm);
> +	madvise_unlock(mm, behavior);
>
>  	return error;
>  }
> --
> 2.39.5

On Thu, Jan 16, 2025 at 05:30:55PM -0800, SeongJae Park wrote:
> Split out the madvise behavior-dependent mmap_lock operations from
> do_madvise(), for easier reuse of the logic in an upcoming change.
> 
> Signed-off-by: SeongJae Park <sj@kernel.org>

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