mm: remove __GFP_NOFAIL is deprecated comment

[linux-2.6-block.git] / mm / zsmalloc.c

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index e7414cec220b3bce6cd5abbdd6a769f1f2c334a5..2d7c4c11fc635d3822d64e8b2d796414945305f7 100644 (file)
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -309,7 +309,12 @@ static void free_handle(struct zs_pool *pool, unsigned long handle)
 
 static void record_obj(unsigned long handle, unsigned long obj)
 {
-       *(unsigned long *)handle = obj;
+       /*
+        * lsb of @obj represents handle lock while other bits
+        * represent object value the handle is pointing so
+        * updating shouldn't do store tearing.
+        */
+       WRITE_ONCE(*(unsigned long *)handle, obj);
 }
 
 /* zpool driver */
@@ -1635,6 +1640,13 @@ static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
                free_obj = obj_malloc(d_page, class, handle);
                zs_object_copy(free_obj, used_obj, class);
                index++;
+               /*
+                * record_obj updates handle's value to free_obj and it will
+                * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
+                * breaks synchronization using pin_tag(e,g, zs_free) so
+                * let's keep the lock bit.
+                */
+               free_obj |= BIT(HANDLE_PIN_BIT);
                record_obj(handle, free_obj);
                unpin_tag(handle);
                obj_free(pool, class, used_obj);