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Commit 0dd1c7bb authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds
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mm/rmap: extend rmap_walk_xxx() to cope with different cases 



There are a lot of common parts in traversing functions, but there are
also a little of uncommon parts in it.  By assigning proper function
pointer on each rmap_walker_control, we can handle these difference
correctly.

Following are differences we should handle.

1. difference of lock function in anon mapping case
2. nonlinear handling in file mapping case
3. prechecked condition:
	checking memcg in page_referenced(),
	checking VM_SHARE in page_mkclean()
	checking temporary vma in try_to_unmap()
4. exit condition:
	checking page_mapped() in try_to_unmap()

So, in this patch, I introduce 4 function pointers to handle above
differences.

Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya 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 051ac83a

include/linux/rmap.h

+15 −0
Original line number Diff line number Diff line
@@ -235,10 +235,25 @@ struct anon_vma *page_lock_anon_vma_read(struct page *page); 
void page_unlock_anon_vma_read(struct anon_vma *anon_vma);

int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);



/*

 * rmap_walk_control: To control rmap traversing for specific needs

 *

 * arg: passed to rmap_one() and invalid_vma()

 * rmap_one: executed on each vma where page is mapped

 * done: for checking traversing termination condition

 * file_nonlinear: for handling file nonlinear mapping

 * anon_lock: for getting anon_lock by optimized way rather than default

 * invalid_vma: for skipping uninterested vma

 */

struct rmap_walk_control {

	void *arg;

	int (*rmap_one)(struct page *page, struct vm_area_struct *vma,

					unsigned long addr, void *arg);

	int (*done)(struct page *page);

	int (*file_nonlinear)(struct page *, struct address_space *,

					struct vm_area_struct *vma);

	struct anon_vma *(*anon_lock)(struct page *page);

	bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);

};



/*

mm/ksm.c

+7 −0
Original line number Diff line number Diff line
@@ -2032,12 +2032,19 @@ again: 
			if ((rmap_item->mm == vma->vm_mm) == search_new_forks)

				continue;



			if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))

				continue;



			ret = rwc->rmap_one(page, vma,

					rmap_item->address, rwc->arg);

			if (ret != SWAP_AGAIN) {

				anon_vma_unlock_read(anon_vma);

				goto out;

			}

			if (rwc->done && rwc->done(page)) {

				anon_vma_unlock_read(anon_vma);

				goto out;

			}

		}

		anon_vma_unlock_read(anon_vma);

	}

mm/rmap.c

+29 −8
Original line number Diff line number Diff line
@@ -1684,10 +1684,14 @@ void __put_anon_vma(struct anon_vma *anon_vma) 
}



#ifdef CONFIG_MIGRATION

static struct anon_vma *rmap_walk_anon_lock(struct page *page)

static struct anon_vma *rmap_walk_anon_lock(struct page *page,

					struct rmap_walk_control *rwc)

{

	struct anon_vma *anon_vma;



	if (rwc->anon_lock)

		return rwc->anon_lock(page);



	/*

	 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()

	 * because that depends on page_mapped(); but not all its usages
@@ -1713,16 +1717,22 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc) 
	struct anon_vma_chain *avc;

	int ret = SWAP_AGAIN;



	anon_vma = rmap_walk_anon_lock(page);

	anon_vma = rmap_walk_anon_lock(page, rwc);

	if (!anon_vma)

		return ret;



	anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {

		struct vm_area_struct *vma = avc->vma;

		unsigned long address = vma_address(page, vma);



		if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))

			continue;



		ret = rwc->rmap_one(page, vma, address, rwc->arg);

		if (ret != SWAP_AGAIN)

			break;

		if (rwc->done && rwc->done(page))

			break;

	}

	anon_vma_unlock_read(anon_vma);

	return ret;
@@ -1740,15 +1750,26 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) 
	mutex_lock(&mapping->i_mmap_mutex);

	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {

		unsigned long address = vma_address(page, vma);



		if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))

			continue;



		ret = rwc->rmap_one(page, vma, address, rwc->arg);

		if (ret != SWAP_AGAIN)

			break;

			goto done;

		if (rwc->done && rwc->done(page))

			goto done;

	}

	/*

	 * No nonlinear handling: being always shared, nonlinear vmas

	 * never contain migration ptes.  Decide what to do about this

	 * limitation to linear when we need rmap_walk() on nonlinear.

	 */



	if (!rwc->file_nonlinear)

		goto done;



	if (list_empty(&mapping->i_mmap_nonlinear))

		goto done;



	ret = rwc->file_nonlinear(page, mapping, vma);



done:

	mutex_unlock(&mapping->i_mmap_mutex);

	return ret;

}