From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 4 Oct 2006 16:39:35 -0400 From: Dave Jones Subject: Re: 2.6.18: Kernel BUG at mm/rmap.c:522 Message-ID: <20061004203935.GB32161@redhat.com> References: <20061004104018.GB22487@skl-net.de> <4523BE45.5050205@yahoo.com.au> <20061004154227.GD22487@skl-net.de> <1159976940.27331.0.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1159976940.27331.0.camel@twins> Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: Andre Noll , Nick Piggin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, andrea@suse.de, riel@redhat.com List-ID: On Wed, Oct 04, 2006 at 05:49:00PM +0200, Peter Zijlstra wrote: > > > It is also nice if we can work out where the page actually came from. The > > > following attached patch should help out a bit with that, if you could > > > run with it? > > Okay. I'll reboot with your patch and let you know if it crashes again. > enable CONFIG_DEBUG_VM to get that. Given this warnings still pops up from time to time, I question whether putting that check under DEBUG_VM was such a good idea. It's not as if it's a major performance impact. This has potential for us to lose valuable debugging info for a few nanoseconds performance increase in an already costly path. This patch brings it back unconditionally, and moves the BUG() into the if arm. Signed-off-by: Dave Jones --- local-git/mm/rmap.c~ 2006-10-04 16:38:06.000000000 -0400 +++ local-git/mm/rmap.c 2006-10-04 16:38:24.000000000 -0400 @@ -576,15 +576,14 @@ void page_add_file_rmap(struct page *pag void page_remove_rmap(struct page *page) { if (atomic_add_negative(-1, &page->_mapcount)) { -#ifdef CONFIG_DEBUG_VM if (unlikely(page_mapcount(page) < 0)) { printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page)); printk (KERN_EMERG " page->flags = %lx\n", page->flags); printk (KERN_EMERG " page->count = %x\n", page_count(page)); printk (KERN_EMERG " page->mapping = %p\n", page->mapping); + BUG(); } -#endif - BUG_ON(page_mapcount(page) < 0); + /* * It would be tidy to reset the PageAnon mapping here, * but that might overwrite a racing page_add_anon_rmap -- http://www.codemonkey.org.uk -- 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