* [patch] mm, thp: copying user pages must schedule on collapse
@ 2017-05-10 21:27 David Rientjes
2017-05-11 9:51 ` Vlastimil Babka
0 siblings, 1 reply; 2+ messages in thread
From: David Rientjes @ 2017-05-10 21:27 UTC (permalink / raw)
To: Andrew Morton
Cc: Kirill A. Shutemov, Johannes Weiner, Vlastimil Babka, Mel Gorman,
linux-kernel, linux-mm
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.
Signed-off-by: David Rientjes <rientjes@google.com>
---
mm/khugepaged.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
--- 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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^ permalink raw reply [flat|nested] 2+ messages in thread* Re: [patch] mm, thp: copying user pages must schedule on collapse
2017-05-10 21:27 [patch] mm, thp: copying user pages must schedule on collapse David Rientjes
@ 2017-05-11 9:51 ` Vlastimil Babka
0 siblings, 0 replies; 2+ messages in thread
From: Vlastimil Babka @ 2017-05-11 9:51 UTC (permalink / raw)
To: David Rientjes, Andrew Morton
Cc: Kirill A. Shutemov, Johannes Weiner, Mel Gorman, linux-kernel, linux-mm
On 05/10/2017 11:27 PM, David Rientjes wrote:
> 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.
>
> Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> mm/khugepaged.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> --- 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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