mm/mmap.c: remove verify_mm_writelocked()

We should get rid of this function.  It no longer serves its purpose.
This is a historical artifact from 2005 where do_brk was called outside of
the core mm.  We do have a proper abstraction in vm_brk_flags and that one
does the locking properly so there is no need to use this function.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Yangtao Li <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: David Rientjes <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dominik Brodowski <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Woodhouse <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 0 insertions, 16 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 7bb64381e77c..f901065c4c64 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2973,16 +2973,6 @@ out:
 	return ret;
 }
 
-static inline void verify_mm_writelocked(struct mm_struct *mm)
-{
-#ifdef CONFIG_DEBUG_VM
-	if (unlikely(down_read_trylock(&mm->mmap_sem))) {
-		WARN_ON(1);
-		up_read(&mm->mmap_sem);
-	}
-#endif
-}
-
 /*
  *  this is really a simplified "do_mmap".  it only handles
  *  anonymous maps.  eventually we may be able to do some
@@ -3010,12 +3000,6 @@ static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long fla
 		return error;
 
 	/*
-	 * mm->mmap_sem is required to protect against another thread
-	 * changing the mappings in case we sleep.
-	 */
-	verify_mm_writelocked(mm);
-
-	/*
 	 * Clear old maps.  this also does some error checking for us
 	 */
 	while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,