Merge ssh://master.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-x86

* ssh://master.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-x86:
  x86: fix global_flush_tlb() bug

1 files changed, 7 insertions, 2 deletions

diff --git a/arch/x86/mm/pageattr_64.c b/arch/x86/mm/pageattr_64.c
index 8a4f65bf956e..c7b7dfe1d405 100644
--- a/arch/x86/mm/pageattr_64.c
+++ b/arch/x86/mm/pageattr_64.c
@@ -230,9 +230,14 @@ void global_flush_tlb(void)
         struct page *pg, *next;
         struct list_head l;
 
-        down_read(&init_mm.mmap_sem);
+        /*
+         * Write-protect the semaphore, to exclude two contexts
+         * doing a list_replace_init() call in parallel and to
+         * exclude new additions to the deferred_pages list:
+         */
+        down_write(&init_mm.mmap_sem);
         list_replace_init(&deferred_pages, &l);
-        up_read(&init_mm.mmap_sem);
+        up_write(&init_mm.mmap_sem);
 
         flush_map(&l);