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

[Randy Dunlap <randy.dunlap@oracle.com>]

Andrew Morton wrote:
> On Tue, 26 May 2009 10:23:36 -0400 (EDT)
> Christoph Lameter <cl@linux.com> wrote:
> 
>> @@ -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);
>>  	return (swp_entry_t) {0};
>> Index: linux-2.6/mm/vmscan.c
>> ===================================================================
>> --- linux-2.6.orig/mm/vmscan.c	2009-05-26 09:06:03.000000000 -0500
>> +++ linux-2.6/mm/vmscan.c	2009-05-26 09:20:30.000000000 -0500
>> @@ -1945,6 +1945,15 @@ out:
>>  		goto loop_again;
>>  	}
>>
>> +	/*
>> +	 * If we had an out of swap condition but things have improved then
>> +	 * reset the flag so that we print the message again when we run
>> +	 * out of swap again.
>> +	 */
>> +#ifdef CONFIG_SWAP
>> +	if (out_of_swap_message_printed && !vm_swap_full())
>> +		out_of_swap_message_printed = 0;
>> +#endif
>>  	return sc.nr_reclaimed;
>>  }
> 
> I still worry that there may be usage patterns which will result in
> this message coming out many times.

and using printk_ratelimit() or printk_timed_ratelimit() would be OK or not?

-- 
~Randy
LPC 2009, Sept. 23-25, Portland, Oregon
http://linuxplumbersconf.org/2009/

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