[patch 2/14] x86, mm: add release_locked_buffer_on_behalf

[Markus Metzger]

Allow the release of a locked buffer on behalf of another task.


Signed-off-by: Markus Metzger <markus.t.metzger@xxxxxxxxx>
---

Index: git-tip/include/linux/mm.h
===================================================================
--- git-tip.orig/include/linux/mm.h	2009-03-23 16:23:19.000000000 +0100
+++ git-tip/include/linux/mm.h	2009-03-23 16:33:03.000000000 +0100
@@ -13,6 +13,7 @@
 #include <linux/prio_tree.h>
 #include <linux/debug_locks.h>
 #include <linux/mm_types.h>
+#include <linux/sched.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -1318,6 +1319,11 @@ void vmemmap_populate_print_last(void);
 
 extern void *alloc_locked_buffer(size_t size);
 extern void free_locked_buffer(void *buffer, size_t size);
-extern void release_locked_buffer(void *buffer, size_t size);
+extern void release_locked_buffer_on_behalf(struct mm_struct *mm,
+					    void *buffer, size_t size);
+static inline void release_locked_buffer(void *buffer, size_t size)
+{
+	release_locked_buffer_on_behalf(current->mm, buffer, size);
+}
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */
Index: git-tip/mm/mlock.c
===================================================================
--- git-tip.orig/mm/mlock.c	2009-03-23 16:23:19.000000000 +0100
+++ git-tip/mm/mlock.c	2009-03-23 16:24:24.000000000 +0100
@@ -660,16 +660,17 @@ void *alloc_locked_buffer(size_t size)
 	return buffer;
 }
 
-void release_locked_buffer(void *buffer, size_t size)
+void release_locked_buffer_on_behalf(struct mm_struct *mm,
+				     void *buffer, size_t size)
 {
 	unsigned long pgsz = PAGE_ALIGN(size) >> PAGE_SHIFT;
 
-	down_write(&current->mm->mmap_sem);
+	down_write(&mm->mmap_sem);
 
-	current->mm->total_vm  -= pgsz;
-	current->mm->locked_vm -= pgsz;
+	mm->total_vm  -= pgsz;
+	mm->locked_vm -= pgsz;
 
-	up_write(&current->mm->mmap_sem);
+	up_write(&mm->mmap_sem);
 }
 
 void free_locked_buffer(void *buffer, size_t size)
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