Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753522AbaBYRpx (ORCPT ); Tue, 25 Feb 2014 12:45:53 -0500 Received: from mail-ob0-f173.google.com ([209.85.214.173]:39940 "EHLO mail-ob0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752635AbaBYRpv (ORCPT ); Tue, 25 Feb 2014 12:45:51 -0500 MIME-Version: 1.0 In-Reply-To: <343228200.20140213224922@eikelenboom.it> References: <1859471893.20140126115521@eikelenboom.it> <20140127000305.GA14236@electric-eye.fr.zoreil.com> <84816226.20140206123631@eikelenboom.it> <942972114.20140206140909@eikelenboom.it> <1434499348.20140211205617@eikelenboom.it> <1392178661.1752.1.camel@edumazet-glaptop2.roam.corp.google.com> <1392322487.11022.4.camel@dwillia2-mobl2.amr.corp.intel.com> <343228200.20140213224922@eikelenboom.it> Date: Tue, 25 Feb 2014 12:45:49 -0500 X-Google-Sender-Auth: eKXLBlggIbh8VpKi8MD1vRhslbE Message-ID: Subject: Re: 3.14-mw regression: rtl8169 WARNING: DMA-API: exceeded 7 overlapping mappings of pfn 55ebe From: Josh Boyer To: Sander Eikelenboom Cc: Dan Williams , Eric Dumazet , Konrad Rzeszutek Wilk , Wei Liu , Francois Romieu , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Dave Jones , Russell King Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 13, 2014 at 4:49 PM, Sander Eikelenboom wrote: > > Thursday, February 13, 2014, 9:14:47 PM, you wrote: > >> On Tue, 2014-02-11 at 20:17 -0800, Eric Dumazet wrote: >>> On Tue, 2014-02-11 at 18:07 -0800, Dan Williams wrote: >>> >>> > The overlap granularity is too large. Multiple dma_map_single >>> > mappings are allowed to a given page as long as they don't collide on >>> > the same cache line. >>> > >>> >>> I am not sure why you try number of mappings of a page. >>> >>> Try launching 100 concurrent netperf -t TCP_SENFILE >>> >>> Same page might be mapped more than 100 times, more than 10000 times in >>> some cases. > >> Thanks for that test case. > >> I updated the fix patch with the following. > >> diff --git a/lib/dma-debug.c b/lib/dma-debug.c >> index 42b12740940b..611010df1e9c 100644 >> --- a/lib/dma-debug.c >> +++ b/lib/dma-debug.c >> @@ -513,6 +513,13 @@ static int active_cln_insert(struct dma_debug_entry *entry) >> unsigned long flags; >> int rc; >> >> + /* If the device is not writing memory then we don't have any >> + * concerns about the cpu consuming stale data. This mitigates >> + * legitimate usages of overlapping mappings. >> + */ > + if (entry->>direction == DMA_TO_DEVICE) >> + return 0; >> + >> spin_lock_irqsave(&radix_lock, flags); >> rc = radix_tree_insert(&dma_active_cacheline, to_cln(entry), entry); >> if (rc == -EEXIST) >> @@ -526,6 +533,10 @@ static void active_cln_remove(struct dma_debug_entry *entry) >> { >> unsigned long flags; >> >> + /* ...mirror the insert case */ > + if (entry->>direction == DMA_TO_DEVICE) >> + return; >> + >> spin_lock_irqsave(&radix_lock, flags); >> /* since we are counting overlaps the final put of the >> * cacheline will occur when the overlap count is 0. > > >> Sander, barring a negative test result from you I'll send the attached >> patch to Andrew. > > Hi Dan, > > That seems to effectively suppress the warning, thanks and: > > Tested-by; Sander Eikelenboom Is there a reason this isn't in Linus' tree yet? josh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/