linux-kernel - [PATCH 63/64] mm/mmap: hack drop down_write_nest

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Message-Id: <20180205012754.23615-64-dbueso@wotan.suse.de>
Date:   Mon,  5 Feb 2018 02:27:53 +0100
From:   Davidlohr Bueso <dbueso@...e.de>
To:     akpm@...ux-foundation.org, mingo@...nel.org
Cc:     peterz@...radead.org, ldufour@...ux.vnet.ibm.com, jack@...e.cz,
        mhocko@...nel.org, kirill.shutemov@...ux.intel.com,
        mawilcox@...rosoft.com, mgorman@...hsingularity.net,
        dave@...olabs.net, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 63/64] mm/mmap: hack drop down_write_nest_lock()

From: Davidlohr Bueso <dave@...olabs.net>

* THIS IS A HACK *

Directly call down_write() on i_mmap_rwsem (such that
we don't have to convert it to a range lock)

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 mm/mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index e10d005f7e2f..1d3a5edd19b2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3394,7 +3394,7 @@ 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
@@ -3424,7 +3424,7 @@ 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);
 	}
 }
 
-- 
2.13.6