From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 847F76B005A for ; Sun, 24 May 2009 22:38:56 -0400 (EDT) Message-ID: <4A1A057A.3080203@oracle.com> Date: Sun, 24 May 2009 19:42:02 -0700 From: Randy Dunlap MIME-Version: 1.0 Subject: Re: [PATCH] Warn if we run out of swap space References: <20090524144056.0849.A69D9226@jp.fujitsu.com> In-Reply-To: <20090524144056.0849.A69D9226@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Christoph Lameter , akpm@linux-foundation.org, linux-mm@kvack.org, Pavel Machek , Dave Hansen List-ID: KOSAKI Motohiro wrote: > Hi > > I have two question. > > >> 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. >> >> Signed-off-by: Christoph Lameter >> >> --- >> mm/swapfile.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> Index: linux-2.6/mm/swapfile.c >> =================================================================== >> --- linux-2.6.orig/mm/swapfile.c 2009-05-22 12:25:19.000000000 -0500 >> +++ linux-2.6/mm/swapfile.c 2009-05-22 13:56:10.000000000 -0500 >> @@ -380,6 +380,7 @@ swp_entry_t get_swap_page(void) >> pgoff_t offset; >> int type, next; >> int wrapped = 0; >> + static int printed = 0; >> >> spin_lock(&swap_lock); >> if (nr_swap_pages <= 0) >> @@ -410,6 +411,10 @@ swp_entry_t get_swap_page(void) >> } >> >> nr_swap_pages++; >> + if (!printed) { >> + printed = 1; >> + printk(KERN_WARNING "All of swap is in use. Some pages cannot be swapped out."); >> + } > > Why don't you use WARN_ONCE()? Someone earlier in this patch thread (maybe Pavel?) commented that WARN_ONCE() would cause a stack dump and that would be too harsh, especially for users. I.e., just the message is needed here, not a stack dump. > lumpy reclaim on no swap system makes this warnings, right? > if so, I think it's a bit annoy. > > > >> noswap: >> spin_unlock(&swap_lock); >> return (swp_entry_t) {0}; -- ~Randy LPC 2009, Sept. 23-25, Portland, Oregon http://linuxplumbersconf.org/2009/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org