commit ad33945175bed649ca5fe0881269db005bbb449a
author Ingo Molnar <mingo@elte.hu> Mon Jul 03 00:25:15 2006 -0700
committer Linus Torvalds <torvalds@g5.osdl.org> Mon Jul 03 15:27:08 2006 -0700
tree 2aac47ea54ac59f33e8188e25e1e9d9807eecae7
parent d378834840907326ac9d448056d957d13cc3718f

[PATCH] lockdep: annotate ->mmap_sem

Teach special (recursive) locking code to the lock validator.  Has no effect
on non-lockdep kernels.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index 7f48abd..54953d8 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -193,7 +193,10 @@
 
 	down_write(&oldmm->mmap_sem);
 	flush_cache_mm(oldmm);
-	down_write(&mm->mmap_sem);
+	/*
+	 * Not linked in yet - no deadlock potential:
+	 */
+	down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
 
 	mm->locked_vm = 0;
 	mm->mmap = NULL;