Re: [PATCH] Warn if we run out of swap space

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Tue, 26 May 2009 10:23:36 -0400 (EDT)
Christoph Lameter <cl@linux.com> wrote:

> 
> Subject: Warn if we run out of swap space
> 
> Running out of swap space means that the evicton of anonymous pages may no longer
> be possible which can lead to OOM conditions.
> 
> Print a warning when swap space first becomes exhausted.
> We do not use WARN_ON because that would perform a meaningless stack dump.
> 
> Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
> 
> ---
>  include/linux/swap.h |    1 +
>  mm/swapfile.c        |    7 +++++++
>  mm/vmscan.c          |    9 +++++++++
>  3 files changed, 17 insertions(+)
> 
> Index: linux-2.6/mm/swapfile.c
> ===================================================================
> --- linux-2.6.orig/mm/swapfile.c	2009-05-22 14:03:37.000000000 -0500
> +++ linux-2.6/mm/swapfile.c	2009-05-26 09:11:52.000000000 -0500
> @@ -374,6 +374,8 @@ no_page:
>  	return 0;
>  }
> 
> +int out_of_swap_message_printed = 0;
> +
>  swp_entry_t get_swap_page(void)
>  {
>  	struct swap_info_struct *si;
> @@ -410,6 +412,11 @@ swp_entry_t get_swap_page(void)
>  	}
> 
>  	nr_swap_pages++;
> +	if (!out_of_swap_message_printed) {
> +		out_of_swap_message_printed = 1;
> +		printk(KERN_WARNING "All of swap is in use. Some pages "
> +			"cannot be swapped out.\n");
> +	}
>  noswap:
>  	spin_unlock(&swap_lock);
BTW, hmm

Isn't this should be
==
noswap:
	if (total_swap_pages && !out_of_swap_message_printed) {
		....
	}
==

?
-Kame




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