+ mm-thp-remove-cond_resched-from-__collapse_huge_page_copy.patch added to -mm tree

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The patch titled
     Subject: mm, thp: remove cond_resched from __collapse_huge_page_copy
has been added to the -mm tree.  Its filename is
     mm-thp-remove-cond_resched-from-__collapse_huge_page_copy.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-thp-remove-cond_resched-from-__collapse_huge_page_copy.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-remove-cond_resched-from-__collapse_huge_page_copy.patch

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------------------------------------------------------
From: David Rientjes <rientjes@xxxxxxxxxx>
Subject: mm, thp: remove cond_resched from __collapse_huge_page_copy

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

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
doing

	if (in_atomic())
		cond_resched()

to cover only non-CONFIG_HIGHPTE configs.

Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1706191341550.97821@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Reported-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

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

diff -puN mm/khugepaged.c~mm-thp-remove-cond_resched-from-__collapse_huge_page_copy mm/khugepaged.c
--- a/mm/khugepaged.c~mm-thp-remove-cond_resched-from-__collapse_huge_page_copy
+++ a/mm/khugepaged.c
@@ -652,7 +652,6 @@ static void __collapse_huge_page_copy(pt
 			spin_unlock(ptl);
 			free_page_and_swap_cache(src_page);
 		}
-		cond_resched();
 	}
 }
 
_

Patches currently in -mm which might be from rientjes@xxxxxxxxxx are

mm-thp-remove-cond_resched-from-__collapse_huge_page_copy.patch
mm-vmscan-avoid-thrashing-anon-lru-when-free-file-is-low.patch
mm-vmpressure-pass-through-notification-support.patch
mm-hugetlb-schedule-when-potentially-allocating-many-hugepages.patch
fs-epoll-short-circuit-fetching-events-if-thread-has-been-killed.patch

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