From 338a16ba154959b049458d4f507d60f694550b68 Mon Sep 17 00:00:00 2001
From: David Rientjes <rientjes@google.com>
Date: Fri, 12 May 2017 15:47:03 -0700
Subject: [PATCH] mm, thp: copying user pages must schedule on collapse
We have encountered need_resched warnings in __collapse_huge_page_copy()
while doing {clear,copy}_user_highpage() over HPAGE_PMD_NR source pages.
mm->mmap_sem is held for write, but the iteration is well bounded.
Reschedule as needed.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1705101426380.109808@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/khugepaged.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d1943e54ba95e..945fd1ca49b5a 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -612,7 +612,8 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
spinlock_t *ptl)
{
pte_t *_pte;
- for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
+ for (_pte = pte; _pte < pte + HPAGE_PMD_NR;
+ _pte++, page++, address += PAGE_SIZE) {
pte_t pteval = *_pte;
struct page *src_page;
@@ -651,9 +652,7 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
spin_unlock(ptl);
free_page_and_swap_cache(src_page);
}
-
- address += PAGE_SIZE;
- page++;
+ cond_resched();
}
}
--
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