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: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 6a456ce..616aa4d 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -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);
};
/*
diff --git a/mm/ksm.c b/mm/ksm.c
index c3035fe..91b8cb3 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -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);
}
diff --git a/mm/rmap.c b/mm/rmap.c
index 1ef74e2..a292707 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1680,10 +1680,14 @@ 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
@@ -1709,16 +1713,22 @@ 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;
@@ -1736,15 +1746,26 @@ 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;
}
--
1.7.9.5
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