1 files changed, 25 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0734bedabd9c..298f307c63a1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -76,6 +76,31 @@ unsigned long totalreserve_pages __read_mostly;
 int percpu_pagelist_fraction;
 gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
 
+#ifdef CONFIG_PM_SLEEP
+/*
+ * The following functions are used by the suspend/hibernate code to temporarily
+ * change gfp_allowed_mask in order to avoid using I/O during memory allocations
+ * while devices are suspended.  To avoid races with the suspend/hibernate code,
+ * they should always be called with pm_mutex held (gfp_allowed_mask also should
+ * only be modified with pm_mutex held, unless the suspend/hibernate code is
+ * guaranteed not to run in parallel with that modification).
+ */
+void set_gfp_allowed_mask(gfp_t mask)
+{
+        WARN_ON(!mutex_is_locked(&pm_mutex));
+        gfp_allowed_mask = mask;
+}
+
+gfp_t clear_gfp_allowed_mask(gfp_t mask)
+{
+        gfp_t ret = gfp_allowed_mask;
+
+        WARN_ON(!mutex_is_locked(&pm_mutex));
+        gfp_allowed_mask &= ~mask;
+        return ret;
+}
+#endif /* CONFIG_PM_SLEEP */
+
 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
 int pageblock_order __read_mostly;
 #endif