From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id F32016B004F for ; Sat, 23 May 2009 00:42:20 -0400 (EDT) Date: Fri, 22 May 2009 21:38:47 -0700 From: Andrew Morton Subject: Re: [PATCH] Warn if we run out of swap space Message-Id: <20090522213847.5f4a276b.akpm@linux-foundation.org> In-Reply-To: References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: linux-mm@kvack.org, Pavel Machek , Dave Hansen List-ID: On Fri, 22 May 2009 14:58:19 -0400 (EDT) Christoph Lameter 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. > > 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."); > + } > noswap: > spin_unlock(&swap_lock); > return (swp_entry_t) {0}; I think the warning is useful. (Although the missing \n makes me wonder how well tested this is). However the once-per-boot thing weakens it quite a lot. Suppose someone runs out of swap, sees the message, adds more swap then later runs out again? Perhaps we could clear the `printed' flag each time the amount of online swap is altered? -- 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