Re: [patch v2 -mm] mm, hugetlb: schedule when potentially allocating many hugepages

[Anshuman Khandual]

On 06/10/2017 04:06 AM, David Rientjes wrote:
> A few hugetlb allocators loop while calling the page allocator and can
> potentially prevent rescheduling if the page allocator slowpath is not
> utilized.
> 
> Conditionally schedule when large numbers of hugepages can be allocated.
> 
> Signed-off-by: David Rientjes 

Fixes a task which was getting hung while writing like 1
hugepages (16MB on POWER8) into /proc/sys/vm/nr_hugepages.

Tested-by: Anshuman Khandual 

Re: [patch v2 -mm] mm, hugetlb: schedule when potentially allocating many hugepages

[Mike Kravetz]

On 06/09/2017 03:36 PM, David Rientjes wrote:
> A few hugetlb allocators loop while calling the page allocator and can
> potentially prevent rescheduling if the page allocator slowpath is not
> utilized.
> 
> Conditionally schedule when large numbers of hugepages can be allocated.
> 
> Signed-off-by: David Rientjes 

Thanks for doing this.

Reviewed-by: Mike Kravetz 

-- 
Mike Kravetz

> ---
>  Based on -mm only to prevent merge conflicts with
>  "mm/hugetlb.c: warn the user when issues arise on boot due to hugepages"
> 
>  v2: removed redundant cond_resched() per Mike
> 
>  mm/hugetlb.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1754,6 +1754,7 @@ static int gather_surplus_pages(struct hstate *h, int 
> delta)
>   break;
>   }
>   list_add(&page->lru, &surplus_list);
> + cond_resched();
>   }
>   allocated += i;
>  
> @@ -,6 +2223,7 @@ static void __init hugetlb_hstate_alloc_pages(struct 
> hstate *h)
>   } else if (!alloc_fresh_huge_page(h,
>&node_states[N_MEMORY]))
>   break;
> + cond_resched();
>   }
>   if (i < h->max_huge_pages) {
>   char buf[32];
> 
> --
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> 

[patch v2 -mm] mm, hugetlb: schedule when potentially allocating many hugepages

[David Rientjes]

A few hugetlb allocators loop while calling the page allocator and can
potentially prevent rescheduling if the page allocator slowpath is not
utilized.

Conditionally schedule when large numbers of hugepages can be allocated.

Signed-off-by: David Rientjes 
---
 Based on -mm only to prevent merge conflicts with
 "mm/hugetlb.c: warn the user when issues arise on boot due to hugepages"

 v2: removed redundant cond_resched() per Mike

 mm/hugetlb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1754,6 +1754,7 @@ static int gather_surplus_pages(struct hstate *h, int 
delta)
break;
}
list_add(&page->lru, &surplus_list);
+   cond_resched();
}
allocated += i;
 
@@ -,6 +2223,7 @@ static void __init hugetlb_hstate_alloc_pages(struct 
hstate *h)
} else if (!alloc_fresh_huge_page(h,
 &node_states[N_MEMORY]))
break;
+   cond_resched();
}
if (i < h->max_huge_pages) {
char buf[32];