To free all space utilized for persistent memory, one can write 0 to
/sys/kernel/pram. This will destroy all PRAM nodes that are not
currently being read or written.
---
mm/pram.c | 39 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/mm/pram.c b/mm/pram.c
index 3ad769b..43ad85f 100644
--- a/mm/pram.c
+++ b/mm/pram.c
@@ -697,6 +697,32 @@ static void pram_truncate_node(struct pram_node *node)
}
+/*
+ * Free all nodes that are not under operation.
+ */
+static void pram_truncate(void)
+{
+ struct page *page, *tmp;
+ struct pram_node *node;
+ LIST_HEAD(dispose);
+
+ mutex_lock(&pram_mutex);
+ list_for_each_entry_safe(page, tmp, &pram_nodes, lru) {
+ node = page_address(page);
+ if (!(node->flags & PRAM_ACCMODE_MASK))
+ list_move(&page->lru, &dispose);
+ }
+ mutex_unlock(&pram_mutex);
+
+ while (!list_empty(&dispose)) {
+ page = list_first_entry(&dispose, struct page, lru);
+ list_del(&page->lru);
+ node = page_address(page);
+ pram_truncate_node(node);
+ pram_free_page(node);
+ }
+}
+
static void pram_stream_init(struct pram_stream *ps,
struct pram_node *node, gfp_t gfp_mask)
{
@@ -1189,8 +1215,19 @@ static ssize_t show_pram_sb_pfn(struct kobject *kobj,
return sprintf(buf, "%lx\n", pfn);
}
+static ssize_t store_pram_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;
+ pram_truncate();
+ return count;
+}
+
static struct kobj_attribute pram_sb_pfn_attr =
- __ATTR(pram, 0444, show_pram_sb_pfn, NULL);
+ __ATTR(pram, 0644, show_pram_sb_pfn, store_pram_sb_pfn);
static struct attribute *pram_attrs[] = {
&pram_sb_pfn_attr.attr,
--
1.7.10.4
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