[RFC v2 02/10] mm: Remove nest locking operation with mmap_sem

Laurent Dufour
2017-05-24T11:21:01Z

The range locking framework doesn't yet provide nest locking
operation.

Once the range locking API while provide nested operation support,
this patch will have to be reviewed.

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
---
mm/mmap.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index f82741e199c0..87c8625ae91d 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3284,7 +3284,11 @@ static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
* The LSB of head.next can't change from under us
* because we hold the mm_all_locks_mutex.
*/
+#ifndef CONFIG_MEM_RANGE_LOCK
down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
+#else
+ down_write(&anon_vma->root->rwsem);
+#endif
/*
* We can safely modify head.next after taking the
* anon_vma->root->rwsem. If some other vma in this mm shares
@@ -3314,7 +3318,11 @@ static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
*/
if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
BUG();
+#ifndef CONFIG_MEM_RANGE_LOCK
down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
+#else
+ down_write(&mapping->i_mmap_rwsem);
+#endif
}
}

--
2.7.4