linux-kernel - [PATCH 3/3] mm: thp: split_huge_pmd

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Date:	Fri,  6 May 2016 17:04:00 +0200
From:	Andrea Arcangeli <aarcange@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Cc:	Alex Williamson <alex.williamson@...hat.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>
Subject: [PATCH 3/3] mm: thp: split_huge_pmd_address() comment improvement

Comment is partly wrong, this improves it by including the case of
split_huge_pmd_address() called by try_to_unmap_one if
TTU_SPLIT_HUGE_PMD is set.

Signed-off-by: Andrea Arcangeli <aarcange@...hat.com>
---
 mm/huge_memory.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9086793..1fbe13d 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3031,8 +3031,10 @@ void split_huge_pmd_address(struct vm_area_struct *vma, unsigned long address,
 		return;
 
 	/*
-	 * Caller holds the mmap_sem write mode, so a huge pmd cannot
-	 * materialize from under us.
+	 * Caller holds the mmap_sem write mode or the anon_vma lock,
+	 * so a huge pmd cannot materialize from under us (khugepaged
+	 * holds both the mmap_sem write mode and the anon_vma lock
+	 * write mode).
 	 */
 	__split_huge_pmd(vma, pmd, address, freeze);
 }