Re: [Xen-devel] BUG in xennet_make_frags with paged skb data

2014-11-10 Thread Eric Dumazet
On Mon, 2014-11-10 at 16:42 +, David Vrabel wrote: > On 10/11/14 16:39, Zoltan Kiss wrote: > > > > The BUG_ON suggested by Stefan would be still reasonable: > > > > BUG_ON(((page-compound_head(page))*PAGE_SIZE)+offset+len > > > PAGE_SIZE< > Well, it wouldn't trigger but I don't think it is u

Re: [Xen-devel] BUG in xennet_make_frags with paged skb data

2014-11-10 Thread David Vrabel
On 10/11/14 16:39, Zoltan Kiss wrote: > > The BUG_ON suggested by Stefan would be still reasonable: > > BUG_ON(((page-compound_head(page))*PAGE_SIZE)+offset+len > > PAGE_SIZE

Re: [Xen-devel] BUG in xennet_make_frags with paged skb data

2014-11-10 Thread Zoltan Kiss
On 10/11/14 14:41, David Vrabel wrote: On 10/11/14 14:35, Seth Forshee wrote: On Fri, Nov 07, 2014 at 10:44:15AM +, David Vrabel wrote: On 06/11/14 21:49, Seth Forshee wrote: We've had several reports of hitting the following BUG_ON in xennet_make_frags with 3.2 and 3.13 kernels (I'm cur

Re: [Xen-devel] BUG in xennet_make_frags with paged skb data

2014-11-07 Thread Zoltan Kiss
Hi, On 07/11/14 11:08, Stefan Bader wrote: On 07.11.2014 11:44, David Vrabel wrote: On 06/11/14 21:49, Seth Forshee wrote: We've had several reports of hitting the following BUG_ON in xennet_make_frags with 3.2 and 3.13 kernels (I'm currently awaiting results of testing with 3.17): /

Re: [Xen-devel] BUG in xennet_make_frags with paged skb data

2014-11-07 Thread Stefan Bader
On 07.11.2014 13:21, Zoltan Kiss wrote: > > > On 07/11/14 12:15, Stefan Bader wrote: >> On 07.11.2014 12:22, Eric Dumazet wrote: >>> On Fri, 2014-11-07 at 09:25 +, Zoltan Kiss wrote: >>> >>> Please do not top post. >>> Hi, AFAIK in this scenario your skb frag is wrong. The page

Re: [Xen-devel] BUG in xennet_make_frags with paged skb data

2014-11-07 Thread Zoltan Kiss
On 07/11/14 12:15, Stefan Bader wrote: On 07.11.2014 12:22, Eric Dumazet wrote: On Fri, 2014-11-07 at 09:25 +, Zoltan Kiss wrote: Please do not top post. Hi, AFAIK in this scenario your skb frag is wrong. The page pointer should point to the original compound page (not a member of it),

Re: [Xen-devel] BUG in xennet_make_frags with paged skb data

2014-11-07 Thread Stefan Bader
On 07.11.2014 12:22, Eric Dumazet wrote: > On Fri, 2014-11-07 at 09:25 +, Zoltan Kiss wrote: > > Please do not top post. > >> Hi, >> >> AFAIK in this scenario your skb frag is wrong. The page pointer should >> point to the original compound page (not a member of it), and offset >> should be

Re: [Xen-devel] BUG in xennet_make_frags with paged skb data

2014-11-07 Thread Eric Dumazet
On Fri, 2014-11-07 at 09:25 +, Zoltan Kiss wrote: Please do not top post. > Hi, > > AFAIK in this scenario your skb frag is wrong. The page pointer should > point to the original compound page (not a member of it), and offset > should be set accordingly. > For example, if your compound pag

Re: [Xen-devel] BUG in xennet_make_frags with paged skb data

2014-11-07 Thread Zoltan Kiss
Hi, AFAIK in this scenario your skb frag is wrong. The page pointer should point to the original compound page (not a member of it), and offset should be set accordingly. For example, if your compound page is 16K (4 page), then the page pointer should point to the first page, and if the data s