linux-kernel - [PATCHv7 13/29] thp: run vma_adjust_trans_huge() outside i_mmap

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Date:	Sat, 16 Apr 2016 03:23:44 +0300
From:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:	Hugh Dickins <hughd@...gle.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Dave Hansen <dave.hansen@...el.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Christoph Lameter <cl@...two.org>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Jerome Marchand <jmarchan@...hat.com>,
	Yang Shi <yang.shi@...aro.org>,
	Sasha Levin <sasha.levin@...cle.com>,
	Andres Lagar-Cavilla <andreslc@...gle.com>,
	Ning Qu <quning@...il.com>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCHv7 13/29] thp: run vma_adjust_trans_huge() outside i_mmap_rwsem

vma_addjust_trans_huge() splits pmd if it's crossing VMA boundary.
During split we munlock the huge page which requires rmap walk.
rmap wants to take the lock on its own.

Let's move vma_adjust_trans_huge() outside i_mmap_rwsem to fix this.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 mm/mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index bd2e1a533bc1..df3976af9302 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -678,6 +678,8 @@ again:			remove_next = 1 + (end > next->vm_end);
 		}
 	}
 
+	vma_adjust_trans_huge(vma, start, end, adjust_next);
+
 	if (file) {
 		mapping = file->f_mapping;
 		root = &mapping->i_mmap;
@@ -698,8 +700,6 @@ again:			remove_next = 1 + (end > next->vm_end);
 		}
 	}
 
-	vma_adjust_trans_huge(vma, start, end, adjust_next);
-
 	anon_vma = vma->anon_vma;
 	if (!anon_vma && adjust_next)
 		anon_vma = next->anon_vma;
-- 
2.8.0.rc3