Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b6b19f25 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

ksm: make rmap walks more scalable 



The rmap walks in ksm.c are like those in rmap.c: they can safely be
done with anon_vma_lock_read().

Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Acked-by: default avatarMel Gorman <mgorman@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2832bc19

mm/ksm.c

+8 −8
Original line number Diff line number Diff line
@@ -1624,7 +1624,7 @@ int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg, 
		struct anon_vma_chain *vmac;

		struct vm_area_struct *vma;



		anon_vma_lock_write(anon_vma);

		anon_vma_lock_read(anon_vma);

		anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,

					       0, ULONG_MAX) {

			vma = vmac->vma;
@@ -1648,7 +1648,7 @@ int page_referenced_ksm(struct page *page, struct mem_cgroup *memcg, 
			if (!search_new_forks || !mapcount)

				break;

		}

		anon_vma_unlock(anon_vma);

		anon_vma_unlock_read(anon_vma);

		if (!mapcount)

			goto out;

	}
@@ -1678,7 +1678,7 @@ int try_to_unmap_ksm(struct page *page, enum ttu_flags flags) 
		struct anon_vma_chain *vmac;

		struct vm_area_struct *vma;



		anon_vma_lock_write(anon_vma);

		anon_vma_lock_read(anon_vma);

		anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,

					       0, ULONG_MAX) {

			vma = vmac->vma;
@@ -1697,11 +1697,11 @@ int try_to_unmap_ksm(struct page *page, enum ttu_flags flags) 
			ret = try_to_unmap_one(page, vma,

					rmap_item->address, flags);

			if (ret != SWAP_AGAIN || !page_mapped(page)) {

				anon_vma_unlock(anon_vma);

				anon_vma_unlock_read(anon_vma);

				goto out;

			}

		}

		anon_vma_unlock(anon_vma);

		anon_vma_unlock_read(anon_vma);

	}

	if (!search_new_forks++)

		goto again;
@@ -1731,7 +1731,7 @@ int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *, 
		struct anon_vma_chain *vmac;

		struct vm_area_struct *vma;



		anon_vma_lock_write(anon_vma);

		anon_vma_lock_read(anon_vma);

		anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,

					       0, ULONG_MAX) {

			vma = vmac->vma;
@@ -1749,11 +1749,11 @@ int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *, 


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

			if (ret != SWAP_AGAIN) {

				anon_vma_unlock(anon_vma);

				anon_vma_unlock_read(anon_vma);

				goto out;

			}

		}

		anon_vma_unlock(anon_vma);

		anon_vma_unlock_read(anon_vma);

	}

	if (!search_new_forks++)

		goto again;