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

[Christoph Lameter <cl@linux-foundation.org>]

On Wed, 27 May 2009, KAMEZAWA Hiroyuki wrote:

> >  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) {
> 		....
> 	}

Look at the beginning of get_swap_page():

   spin_lock(&swap_lock);
        if (nr_swap_pages <= 0)
                goto noswap;
        nr_swap_pages--;

I placed the printk intentionally before the noswap label.

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