ring_buffer: reset buffer page when freeing
Mathieu Desnoyers pointed out that the freeing of the page frame needs
to be reset otherwise we might trigger BUG_ON in the page free code.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 95ca933..cfa7113 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -128,6 +128,17 @@
};
/*
+ * Also stolen from mm/slob.c. Thanks to Mathieu Desnoyers for pointing
+ * this issue out.
+ */
+static inline void free_buffer_page(struct buffer_page *bpage)
+{
+ reset_page_mapcount(&bpage->page);
+ bpage->page.mapping = NULL;
+ __free_page(&bpage->page);
+}
+
+/*
* We need to fit the time_stamp delta into 27 bits.
*/
static inline int test_time_stamp(u64 delta)
@@ -240,7 +251,7 @@
free_pages:
list_for_each_entry_safe(page, tmp, &pages, list) {
list_del_init(&page->list);
- __free_page(&page->page);
+ free_buffer_page(page);
}
return -ENOMEM;
}
@@ -284,7 +295,7 @@
list_for_each_entry_safe(page, tmp, head, list) {
list_del_init(&page->list);
- __free_page(&page->page);
+ free_buffer_page(page);
}
kfree(cpu_buffer);
}
@@ -393,7 +404,7 @@
p = cpu_buffer->pages.next;
page = list_entry(p, struct buffer_page, list);
list_del_init(&page->list);
- __free_page(&page->page);
+ free_buffer_page(page);
}
BUG_ON(list_empty(&cpu_buffer->pages));
@@ -520,7 +531,7 @@
free_pages:
list_for_each_entry_safe(page, tmp, &pages, list) {
list_del_init(&page->list);
- __free_page(&page->page);
+ free_buffer_page(page);
}
return -ENOMEM;
}