Commit 0a6ffacb authored by SeongJae Park's avatar SeongJae Park Committed by Andrew Morton
Browse files

mm/madvise: deduplicate madvise_do_behavior() skip case handlings 

The logic for checking if a given madvise() request for a single memory
range can skip real work, namely madvise_do_behavior(), is duplicated in
do_madvise() and vector_madvise().  Split out the logic to a function and
reuse it.

Link: https://lkml.kernel.org/r/20250312164750.59215-4-sj@kernel.org


Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liam R. Howlett <howlett@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f4a578d3

mm/madvise.c

+34 −23
Original line number Diff line number Diff line
@@ -1640,6 +1640,31 @@ static bool is_valid_madvise(unsigned long start, size_t len_in, int behavior) 
	return true;

}



/*

 * madvise_should_skip() - Return if the request is invalid or nothing.

 * @start:	Start address of madvise-requested address range.

 * @len_in:	Length of madvise-requested address range.

 * @behavior:	Requested madvise behavor.

 * @err:	Pointer to store an error code from the check.

 *

 * If the specified behaviour is invalid or nothing would occur, we skip the

 * operation.  This function returns true in the cases, otherwise false.  In

 * the former case we store an error on @err.

 */

static bool madvise_should_skip(unsigned long start, size_t len_in,

		int behavior, int *err)

{

	if (!is_valid_madvise(start, len_in, behavior)) {

		*err = -EINVAL;

		return true;

	}

	if (start + PAGE_ALIGN(len_in) == start) {

		*err = 0;

		return true;

	}

	return false;

}



static bool is_madvise_populate(int behavior)

{

	switch (behavior) {
@@ -1747,23 +1772,15 @@ static int madvise_do_behavior(struct mm_struct *mm, 
 */

int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)

{

	unsigned long end;

	int error;

	size_t len;



	if (!is_valid_madvise(start, len_in, behavior))

		return -EINVAL;



	len = PAGE_ALIGN(len_in);

	end = start + len;



	if (end == start)

		return 0;



	if (madvise_should_skip(start, len_in, behavior, &error))

		return error;

	error = madvise_lock(mm, behavior);

	if (error)

		return error;

	error = madvise_do_behavior(mm, start, len_in, len, behavior);

	error = madvise_do_behavior(mm, start, len_in, PAGE_ALIGN(len_in),

			behavior);

	madvise_unlock(mm, behavior);



	return error;
@@ -1790,19 +1807,13 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter, 
	while (iov_iter_count(iter)) {

		unsigned long start = (unsigned long)iter_iov_addr(iter);

		size_t len_in = iter_iov_len(iter);

		size_t len;



		if (!is_valid_madvise(start, len_in, behavior)) {

			ret = -EINVAL;

			break;

		}

		int error;



		len = PAGE_ALIGN(len_in);

		if (start + len == start)

			ret = 0;

		if (madvise_should_skip(start, len_in, behavior, &error))

			ret = error;

		else

			ret = madvise_do_behavior(mm, start, len_in, len,

					behavior);

			ret = madvise_do_behavior(mm, start, len_in,

					PAGE_ALIGN(len_in), behavior);

		/*

		 * An madvise operation is attempting to restart the syscall,

		 * but we cannot proceed as it would not be correct to repeat