Re: 3.14-mw regression: rtl8169 WARNING: DMA-API: exceeded 7 overlapping mappings of pfn 55ebe
From: Ben Hutchings <hidden>
Date: 2014-02-12 22:53:05
Also in:
lkml
On Tue, 2014-02-11 at 13:28 -0800, Eric Dumazet wrote: [...]
Incoming frames might be taken out of order-3 pages. With regular Ethernet frames, this is 21 frames per order-3 pages. ACTIVE_PFN_MAX_OVERLAP seems too small. Alternative would be to user order-0 only pages if CONFIG_DMA_API_DEBUG is set. Not sure if it works if PAGE_SIZE=66536 ....
Indeed, you can get a lot of packet buffers into a 64K page...
quoted hunk ↗ jump to hunk
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index f589c9af8cbf..1b9995adfd29 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h@@ -1924,7 +1924,11 @@ static inline void __skb_queue_purge(struct sk_buff_head *list) kfree_skb(skb); } +#if defined(CONFIG_DMA_API_DEBUG) +#define NETDEV_FRAG_PAGE_MAX_ORDER 0 +#else #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768) +#endif #define NETDEV_FRAG_PAGE_MAX_SIZE (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER) #define NETDEV_PAGECNT_MAX_BIAS NETDEV_FRAG_PAGE_MAX_SIZE
That may be useful for debugging this particular problem, but please don't make debugging options change behaviour like this. Ben. -- Ben Hutchings If more than one person is responsible for a bug, no one is at fault.
Attachments
- signature.asc [application/pgp-signature] 811 bytes