linux-kernel - [RFC 3/4] Remove nest locking operation with mmap

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Date:   Wed, 19 Apr 2017 14:18:26 +0200
From:   Laurent Dufour <ldufour@...ux.vnet.ibm.com>
To:     linux-mm@...ck.org
Cc:     Davidlohr Bueso <dave@...olabs.net>, akpm@...ux-foundation.org,
        Jan Kara <jack@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Michal Hocko <mhocko@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        haren@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
        khandual@...ux.vnet.ibm.com, Paul.McKenney@...ibm.com,
        linux-kernel@...r.kernel.org
Subject: [RFC 3/4] Remove nest locking operation with mmap_sem

The range locking framework doesn't yet provide nest locking
operation, so remove them assuming that the check is now good.

Signed-off-by: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
---
 mm/mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index cd8fa7e74784..4df13e633e92 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3284,7 +3284,7 @@ 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.
 		 */
-		down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
+		down_write(&anon_vma->root->rwsem);
 		/*
 		 * We can safely modify head.next after taking the
 		 * anon_vma->root->rwsem. If some other vma in this mm shares
@@ -3314,7 +3314,7 @@ 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();
-		down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
+		down_write(&mapping->i_mmap_rwsem);
 	}
 }
 
-- 
2.7.4