[PATCH] hugetlb: Abort a hugepage pool resize if a signal is pending

[PATCH] hugetlb: Abort a hugepage pool resize if a signal is pending

[Mel Gorman]

If a user asks for a hugepage pool resize but specified a large number, the
machine can begin trashing. In response, they might hit ctrl-c but signals
are ignored and the pool resize continues until it fails an allocation. This
can take a considerable amount of time so this patch aborts a pool resize
if a signal is pending.

[dave@linux.vnet.ibm.com: His idea]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
---
 mm/hugetlb.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index af02ee8..a952cb8 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1238,6 +1238,9 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count)
 		if (!ret)
 			goto out;
 
+		/* Bail for signals. Probably ctrl-c from user */
+		if (signal_pending(current))
+			goto out;
 	}
 
 	/*

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Re: [PATCH] hugetlb: Abort a hugepage pool resize if a signal is pending

[Dave Hansen]

On Wed, 2009-12-02 at 14:15 +0000, Mel Gorman wrote:
> If a user asks for a hugepage pool resize but specified a large number, the
> machine can begin trashing. In response, they might hit ctrl-c but signals
> are ignored and the pool resize continues until it fails an allocation. This
> can take a considerable amount of time so this patch aborts a pool resize
> if a signal is pending.
> 
> [dave@linux.vnet.ibm.com: His idea]
> Signed-off-by: Mel Gorman <mel@csn.ul.ie>
> ---
>  mm/hugetlb.c |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index af02ee8..a952cb8 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1238,6 +1238,9 @@ static unsigned long set_max_huge_pages(struct hstate *h, unsigned long count)
>  		if (!ret)
>  			goto out;
> 
> +		/* Bail for signals. Probably ctrl-c from user */
> +		if (signal_pending(current))
> +			goto out;

Thanks, Mel!

This will help m unwedge my system the next time I fat-finger an extra
zero or two into my hugepage pool size.

-- Dave

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