[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH for stable 3.10] xen-netback: drop SKB from internal queue if frontend is disconnected
On Fri, 2014-07-11 at 14:28 +0100, Wei Liu wrote: > On Fri, Jul 11, 2014 at 02:15:29PM +0100, Ian Campbell wrote: > > On Fri, 2014-07-11 at 14:08 +0100, Wei Liu wrote: > > > In 88a810def7 ("xen-netback: fix refcnt unbalance for 3.10"), we moved > > > the ref counting code from xenvif_disconnect to xenvif_free. > > > > Since this was a 3.10 specific backport that explains why this is also > > such? > > > > Yes. OK. > > > It can occur that frontend is disconnected while there's still SKB > > > stuck in netback's rx_queue in rare case. When netback thread wakes up, > > > it will try to write to an already unmapped ring, resulting in kernel > > > oops. > > > > > > Moving the ref counting back to xenvif_disconnect isn't an option as it > > > reintroduces an old bug. Further more, writing into a dead frontend's > > > ring and memory is just wrong. Dropping those SKBs seems to be a good > > > strategy. > > > > > > This patch fixes that corner case: introduce a flag to indicate whether > > > frontend ring is mapped. If the ring is unmapped, just drop those SKBs. > > > > > > This bug only manifests in 3.10 kernel. Kernel >=3.12 doesn't have it. > > > > What about 3.11? > > > > 3.11 is long dead while 3.10 is LTS kernel. I don't think GregKH accepts > patch for 3.11 anymore. Whether Greg would take a patch is orthogonal to whether the bug exists in 3.11 though. Someone might want to fix their own kernel locally for example... Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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