Messages in this thread Patch in this message |  | | Date | Thu, 13 Feb 2014 22:49:22 +0100 | From | Sander Eikelenboom <> | Subject | Re: 3.14-mw regression: rtl8169 WARNING: DMA-API: exceeded 7 overlapping mappings of pfn 55ebe |
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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 <linux@eikelenboom.it>
-- Sander
> -- > Dan
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