To free all space utilized for preserved memory, one can write 0 to
/sys/kernel/pkram. This will destroy all PKRAM nodes that are not
currently being read or written.
Originally-by: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx>
---
mm/pkram.c | 39 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/mm/pkram.c b/mm/pkram.c
index 474fb6fc8355..d404e415f3cb 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c
@@ -493,6 +493,32 @@ static void pkram_truncate_node(struct pkram_node *node)
node->obj_pfn = 0;
}
+/*
+ * Free all nodes that are not under operation.
+ */
+static void pkram_truncate(void)
+{
+ struct page *page, *tmp;
+ struct pkram_node *node;
+ LIST_HEAD(dispose);
+
+ mutex_lock(&pkram_mutex);
+ list_for_each_entry_safe(page, tmp, &pkram_nodes, lru) {
+ node = page_address(page);
+ if (!(node->flags & PKRAM_ACCMODE_MASK))
+ list_move(&page->lru, &dispose);
+ }
+ mutex_unlock(&pkram_mutex);
+
+ while (!list_empty(&dispose)) {
+ page = list_first_entry(&dispose, struct page, lru);
+ list_del(&page->lru);
+ node = page_address(page);
+ pkram_truncate_node(node);
+ pkram_free_page(node);
+ }
+}
+
static void pkram_add_link(struct pkram_link *link, struct pkram_data_stream *pds)
{
__u64 link_pfn = page_to_pfn(virt_to_page(link));
@@ -1252,8 +1278,19 @@ static ssize_t show_pkram_sb_pfn(struct kobject *kobj,
return sprintf(buf, "%lx\n", pfn);
}
+static ssize_t store_pkram_sb_pfn(struct kobject *kobj,
+ struct kobj_attribute *attr, const char *buf, size_t count)
+{
+ int val;
+
+ if (kstrtoint(buf, 0, &val) || val)
+ return -EINVAL;
+ pkram_truncate();
+ return count;
+}
+
static struct kobj_attribute pkram_sb_pfn_attr =
- __ATTR(pkram, 0444, show_pkram_sb_pfn, NULL);
+ __ATTR(pkram, 0644, show_pkram_sb_pfn, store_pkram_sb_pfn);
static struct attribute *pkram_attrs[] = {
&pkram_sb_pfn_attr.attr,
--
1.9.4
