From 338a16ba154959b049458d4f507d60f694550b68 Mon Sep 17 00:00:00 2001 From: David Rientjes 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 Acked-by: Vlastimil Babka Cc: "Kirill A. Shutemov" Cc: Johannes Weiner Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/khugepaged.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index d1943e54ba95..945fd1ca49b5 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(); } } -- 2.30.2