From b0943d61b8fa420180f92f64ef67662b4f6cc493 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@suse.de>
Date: Wed, 18 Dec 2013 17:08:46 -0800
Subject: mm: numa: defer TLB flush for THP migration as long as possible

THP migration can fail for a variety of reasons.  Avoid flushing the TLB
to deal with THP migration races until the copy is ready to start.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/migrate.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'mm/migrate.c')

diff --git a/mm/migrate.c b/mm/migrate.c
index cfb419085261..e9b710201335 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1759,6 +1759,9 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
 		goto out_fail;
 	}
 
+	if (mm_tlb_flush_pending(mm))
+		flush_tlb_range(vma, mmun_start, mmun_end);
+
 	/* Prepare a page as a migration target */
 	__set_page_locked(new_page);
 	SetPageSwapBacked(new_page);
-- 
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