All updaters of pgdat size (spanned_pages, start_pfn, and
present_pages) currently also hold lock_memory_hotplug() (in addition
to pgdat_resize_lock()).
Document this and make holding of that lock a requirement on the update
side for now, but keep the pgdat_resize_lock() around for readers that
can't lock a mutex.
Signed-off-by: Cody P Schafer <cody@xxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 3 +++
1 file changed, 3 insertions(+)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 5c76737..09ac172 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -716,6 +716,9 @@ typedef struct pglist_data {
* or node_spanned_pages stay constant. Holding this will also
* guarantee that any pfn_valid() stays that way.
*
+ * Updaters of any of these fields also must hold
+ * lock_memory_hotplug().
+ *
* Nests above zone->lock and zone->size_seqlock.
*/
spinlock_t node_size_lock;
--
1.8.2.2
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