[PATCH v1 6/7] virtio-mem: use page_offline_(start|end) when setting PageOffline()

David Hildenbrand
2021-04-29T12:26:52Z

Let's properly use page_offline_(start|end) to synchronize setting
PageOffline(), so we won't have valid page access to unplugged memory
regions from /proc/kcore.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
drivers/virtio/virtio_mem.c | 2 ++
mm/util.c | 2 ++
2 files changed, 4 insertions(+)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 10ec60d81e84..dc2a2e2b2ff8 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -1065,6 +1065,7 @@ static int virtio_mem_memory_notifier_cb(struct notifier_block *nb,
static void virtio_mem_set_fake_offline(unsigned long pfn,
unsigned long nr_pages, bool onlined)
{
+ page_offline_begin();
for (; nr_pages--; pfn++) {
struct page *page = pfn_to_page(pfn);

@@ -1075,6 +1076,7 @@ static void virtio_mem_set_fake_offline(unsigned long pfn,
ClearPageReserved(page);
}
}
+ page_offline_end();
}

/*
diff --git a/mm/util.c b/mm/util.c
index 95395d4e4209..d0e357bd65e6 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -1046,8 +1046,10 @@ void page_offline_begin(void)
{
down_write(&page_offline_rwsem);
}
+EXPORT_SYMBOL(page_offline_begin);

void page_offline_end(void)
{
up_write(&page_offline_rwsem);
}
+EXPORT_SYMBOL(page_offline_end);
--
2.30.2