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: Hugh Dickins <hughd@google.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/ksm.c b/mm/ksm.c
index 82dfb4b..5157385 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1624,7 +1624,7 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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;