[patch for-4.12] mm, thp: remove cond_resched from __collapse_huge_page_copy

From: David Rientjes
Date: Mon Jun 19 2017 - 16:43:44 EST

This is a partial revert of commit 338a16ba1549 ("mm, thp: copying user
pages must schedule on collapse") which added a cond_resched() to

On x86 with CONFIG_HIGHPTE, __collapse_huge_page_copy is called in atomic
context and thus scheduling is not possible. This is only a possible
config on arm and i386.

Although need_resched has been shown to be set for over 100 jiffies while
doing the iteration in __collapse_huge_page_copy, this is better than

if (in_atomic())

to cover only non-CONFIG_HIGHPTE configs.

Reported-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Note: Larry should be back as of June 17 to test if this fixes the
reported issue.

mm/khugepaged.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -652,7 +652,6 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
- cond_resched();