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Commit 0f843c6a authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds
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mm/rmap: factor nonlinear handling out of try_to_unmap_file() 



To merge all kinds of rmap traverse functions, try_to_unmap(),
try_to_munlock(), page_referenced() and page_mkclean(), we need to
extract common parts and separate out non-common parts.

Nonlinear handling is handled just in try_to_unmap_file() and other rmap
traverse functions doesn't care of it.  Therfore it is better to factor
nonlinear handling out of try_to_unmap_file() in order to merge all
kinds of rmap traverse functions easily.

Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b854f711

mm/rmap.c

+74 −62
Original line number Diff line number Diff line
@@ -1426,6 +1426,79 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, 
	return ret;

}



static int try_to_unmap_nonlinear(struct page *page,

		struct address_space *mapping, struct vm_area_struct *vma)

{

	int ret = SWAP_AGAIN;

	unsigned long cursor;

	unsigned long max_nl_cursor = 0;

	unsigned long max_nl_size = 0;

	unsigned int mapcount;



	list_for_each_entry(vma,

		&mapping->i_mmap_nonlinear, shared.nonlinear) {



		cursor = (unsigned long) vma->vm_private_data;

		if (cursor > max_nl_cursor)

			max_nl_cursor = cursor;

		cursor = vma->vm_end - vma->vm_start;

		if (cursor > max_nl_size)

			max_nl_size = cursor;

	}



	if (max_nl_size == 0) {	/* all nonlinears locked or reserved ? */

		return SWAP_FAIL;

	}



	/*

	 * We don't try to search for this page in the nonlinear vmas,

	 * and page_referenced wouldn't have found it anyway.  Instead

	 * just walk the nonlinear vmas trying to age and unmap some.

	 * The mapcount of the page we came in with is irrelevant,

	 * but even so use it as a guide to how hard we should try?

	 */

	mapcount = page_mapcount(page);

	if (!mapcount)

		return ret;



	cond_resched();



	max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;

	if (max_nl_cursor == 0)

		max_nl_cursor = CLUSTER_SIZE;



	do {

		list_for_each_entry(vma,

			&mapping->i_mmap_nonlinear, shared.nonlinear) {



			cursor = (unsigned long) vma->vm_private_data;

			while (cursor < max_nl_cursor &&

				cursor < vma->vm_end - vma->vm_start) {

				if (try_to_unmap_cluster(cursor, &mapcount,

						vma, page) == SWAP_MLOCK)

					ret = SWAP_MLOCK;

				cursor += CLUSTER_SIZE;

				vma->vm_private_data = (void *) cursor;

				if ((int)mapcount <= 0)

					return ret;

			}

			vma->vm_private_data = (void *) max_nl_cursor;

		}

		cond_resched();

		max_nl_cursor += CLUSTER_SIZE;

	} while (max_nl_cursor <= max_nl_size);



	/*

	 * Don't loop forever (perhaps all the remaining pages are

	 * in locked vmas).  Reset cursor on all unreserved nonlinear

	 * vmas, now forgetting on which ones it had fallen behind.

	 */

	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.nonlinear)

		vma->vm_private_data = NULL;



	return ret;

}



bool is_vma_temporary_stack(struct vm_area_struct *vma)

{

	int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
@@ -1515,10 +1588,6 @@ static int try_to_unmap_file(struct page *page, enum ttu_flags flags) 
	pgoff_t pgoff = page->index << compound_order(page);

	struct vm_area_struct *vma;

	int ret = SWAP_AGAIN;

	unsigned long cursor;

	unsigned long max_nl_cursor = 0;

	unsigned long max_nl_size = 0;

	unsigned int mapcount;



	mutex_lock(&mapping->i_mmap_mutex);

	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
@@ -1539,64 +1608,7 @@ static int try_to_unmap_file(struct page *page, enum ttu_flags flags) 
	if (TTU_ACTION(flags) == TTU_MUNLOCK)

		goto out;



	list_for_each_entry(vma, &mapping->i_mmap_nonlinear,

							shared.nonlinear) {

		cursor = (unsigned long) vma->vm_private_data;

		if (cursor > max_nl_cursor)

			max_nl_cursor = cursor;

		cursor = vma->vm_end - vma->vm_start;

		if (cursor > max_nl_size)

			max_nl_size = cursor;

	}



	if (max_nl_size == 0) {	/* all nonlinears locked or reserved ? */

		ret = SWAP_FAIL;

		goto out;

	}



	/*

	 * We don't try to search for this page in the nonlinear vmas,

	 * and page_referenced wouldn't have found it anyway.  Instead

	 * just walk the nonlinear vmas trying to age and unmap some.

	 * The mapcount of the page we came in with is irrelevant,

	 * but even so use it as a guide to how hard we should try?

	 */

	mapcount = page_mapcount(page);

	if (!mapcount)

		goto out;

	cond_resched();



	max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;

	if (max_nl_cursor == 0)

		max_nl_cursor = CLUSTER_SIZE;



	do {

		list_for_each_entry(vma, &mapping->i_mmap_nonlinear,

							shared.nonlinear) {

			cursor = (unsigned long) vma->vm_private_data;

			while ( cursor < max_nl_cursor &&

				cursor < vma->vm_end - vma->vm_start) {

				if (try_to_unmap_cluster(cursor, &mapcount,

						vma, page) == SWAP_MLOCK)

					ret = SWAP_MLOCK;

				cursor += CLUSTER_SIZE;

				vma->vm_private_data = (void *) cursor;

				if ((int)mapcount <= 0)

					goto out;

			}

			vma->vm_private_data = (void *) max_nl_cursor;

		}

		cond_resched();

		max_nl_cursor += CLUSTER_SIZE;

	} while (max_nl_cursor <= max_nl_size);



	/*

	 * Don't loop forever (perhaps all the remaining pages are

	 * in locked vmas).  Reset cursor on all unreserved nonlinear

	 * vmas, now forgetting on which ones it had fallen behind.

	 */

	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.nonlinear)

		vma->vm_private_data = NULL;

	ret = try_to_unmap_nonlinear(page, mapping, vma);

out:

	mutex_unlock(&mapping->i_mmap_mutex);

	return ret;