mm: Prepare decoupling the page fault disabling logic
Add a pagefault_disabled variable to task_struct to allow decoupling
the pagefault-disabled logic from the preempt count.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/mm/memory.c b/mm/memory.c
index 5a35443..924a791 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3757,6 +3757,35 @@
return 0;
}
+void pagefault_disable(void)
+{
+ inc_preempt_count();
+ current->pagefault_disabled++;
+ /*
+ * make sure to have issued the store before a pagefault
+ * can hit.
+ */
+ barrier();
+}
+EXPORT_SYMBOL(pagefault_disable);
+
+void pagefault_enable(void)
+{
+ /*
+ * make sure to issue those last loads/stores before enabling
+ * the pagefault handler again.
+ */
+ barrier();
+ current->pagefault_disabled--;
+ dec_preempt_count();
+ /*
+ * make sure we do..
+ */
+ barrier();
+ preempt_check_resched();
+}
+EXPORT_SYMBOL(pagefault_enable);
+
/*
* By the time we get here, we already hold the mm semaphore
*/