mm, x86, ptrace, bts: defer branch trace stopping

When a ptraced task is unlinked, we need to stop branch tracing for
that task.

Since the unlink is called with interrupts disabled, and we need
interrupts enabled to stop branch tracing, we defer the work.

Collect all branch tracing related stuff in a branch tracing context.

Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: roland@redhat.com
Cc: eranian@googlemail.com
Cc: juan.villacis@intel.com
Cc: ak@linux.jf.intel.com
LKML-Reference: <20090403144550.712401000@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 7 deletions

diff --git a/mm/mlock.c b/mm/mlock.c
index cbe9e0581b75..749383b442c7 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -660,21 +660,20 @@ void *alloc_locked_buffer(size_t size)
         return buffer;
 }
 
-void release_locked_buffer(void *buffer, size_t size)
+void refund_locked_buffer_memory(struct mm_struct *mm, 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)
 {
-        release_locked_buffer(buffer, size);
-
+        refund_locked_buffer_memory(current->mm, size);
         kfree(buffer);
 }