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Commit 3140a227 authored by Brice Goglin's avatar Brice Goglin Committed by Linus Torvalds
Browse files

mm: rework do_pages_move() to work on page_sized chunks 



Rework do_pages_move() to work by page-sized chunks of struct page_to_node
that are passed to do_move_page_to_node_array().  We now only have to
allocate a single page instead a possibly very large vmalloc area to store
all page_to_node entries.

As a result, new_page_node() will now have a very small lookup, hidding
much of the overall sys_move_pages() overhead.

Signed-off-by: default avatarBrice Goglin <Brice.Goglin@inria.fr>
Signed-off-by: default avatarNathalie Furmento <Nathalie.Furmento@labri.fr>
Acked-by: default avatarChristoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 390722ba

mm/migrate.c

+44 −35
Original line number Diff line number Diff line
@@ -919,41 +919,43 @@ static int do_pages_move(struct mm_struct *mm, struct task_struct *task, 
			 const int __user *nodes,

			 int __user *status, int flags)

{

	struct page_to_node *pm = NULL;

	struct page_to_node *pm;

	nodemask_t task_nodes;

	int err = 0;

	int i;

	unsigned long chunk_nr_pages;

	unsigned long chunk_start;

	int err;



	task_nodes = cpuset_mems_allowed(task);



	/* Limit nr_pages so that the multiplication may not overflow */

	if (nr_pages >= ULONG_MAX / sizeof(struct page_to_node) - 1) {

		err = -E2BIG;

		goto out;

	}



	pm = vmalloc((nr_pages + 1) * sizeof(struct page_to_node));

	if (!pm) {

	err = -ENOMEM;

	pm = (struct page_to_node *)__get_free_page(GFP_KERNEL);

	if (!pm)

		goto out;

	}



	/*

	 * Get parameters from user space and initialize the pm

	 * array. Return various errors if the user did something wrong.

	 * Store a chunk of page_to_node array in a page,

	 * but keep the last one as a marker

	 */

	for (i = 0; i < nr_pages; i++) {

	chunk_nr_pages = (PAGE_SIZE / sizeof(struct page_to_node)) - 1;



	for (chunk_start = 0;

	     chunk_start < nr_pages;

	     chunk_start += chunk_nr_pages) {

		int j;



		if (chunk_start + chunk_nr_pages > nr_pages)

			chunk_nr_pages = nr_pages - chunk_start;



		/* fill the chunk pm with addrs and nodes from user-space */

		for (j = 0; j < chunk_nr_pages; j++) {

			const void __user *p;

			int node;



			err = -EFAULT;

		if (get_user(p, pages + i))

			if (get_user(p, pages + j + chunk_start))

				goto out_pm;

			pm[j].addr = (unsigned long) p;



		pm[i].addr = (unsigned long)p;

		if (nodes) {

			int node;



			if (get_user(node, nodes + i))

			if (get_user(node, nodes + j + chunk_start))

				goto out_pm;



			err = -ENODEV;
@@ -964,22 +966,29 @@ static int do_pages_move(struct mm_struct *mm, struct task_struct *task, 
			if (!node_isset(node, task_nodes))

				goto out_pm;



			pm[i].node = node;

		} else

			pm[i].node = 0;	/* anything to not match MAX_NUMNODES */

			pm[j].node = node;

		}

	/* End marker */

	pm[nr_pages].node = MAX_NUMNODES;



	err = do_move_page_to_node_array(mm, pm, flags & MPOL_MF_MOVE_ALL);

	if (err >= 0)

		/* End marker for this chunk */

		pm[chunk_nr_pages].node = MAX_NUMNODES;



		/* Migrate this chunk */

		err = do_move_page_to_node_array(mm, pm,

						 flags & MPOL_MF_MOVE_ALL);

		if (err < 0)

			goto out_pm;



		/* Return status information */

		for (i = 0; i < nr_pages; i++)

			if (put_user(pm[i].status, status + i))

		for (j = 0; j < chunk_nr_pages; j++)

			if (put_user(pm[j].status, status + j + chunk_start)) {

				err = -EFAULT;

				goto out_pm;

			}

	}

	err = 0;



out_pm:

	vfree(pm);

	free_page((unsigned long)pm);

out:

	return err;

}