On Tue, Jul 12, 2016 at 10:31:18AM -0700, Cong Wang wrote: > On Mon, Jul 11, 2016 at 12:45 PM, <nuclear...@nuclearcat.com> wrote: > > Hi > > > > On latest kernel i noticed kernel panic happening 1-2 times per day. It is > > also happening on older kernel (at least 4.5.3). > > > ... > > [42916.426463] Call Trace: > > [42916.426658] <IRQ> > > > > [42916.426719] [<ffffffff81843786>] skb_push+0x36/0x37 > > [42916.427111] [<ffffffffa00e8ce5>] ppp_start_xmit+0x10f/0x150 > > [ppp_generic] > > [42916.427314] [<ffffffff81853467>] dev_hard_start_xmit+0x25a/0x2d3 > > [42916.427516] [<ffffffff818530f2>] ? > > validate_xmit_skb.isra.107.part.108+0x11d/0x238 > > [42916.427858] [<ffffffff8186dee3>] sch_direct_xmit+0x89/0x1b5 > > [42916.428060] [<ffffffff8186e142>] __qdisc_run+0x133/0x170 > > [42916.428261] [<ffffffff81850034>] net_tx_action+0xe3/0x148 > > [42916.428462] [<ffffffff810c401a>] __do_softirq+0xb9/0x1a9 > > [42916.428663] [<ffffffff810c4251>] irq_exit+0x37/0x7c > > [42916.428862] [<ffffffff8102b8f7>] smp_apic_timer_interrupt+0x3d/0x48 > > [42916.429063] [<ffffffff818cb15c>] apic_timer_interrupt+0x7c/0x90 > > Interesting, we call a skb_cow_head() before skb_push() in ppp_start_xmit(), > I have no idea why this could happen. > The skb is corrupted: head is at ffff8800b0bf2800 while data is at ffa00500b0bf284c.
Figuring out how this corruption happened is going to be hard without a way to reproduce the problem. Denys, can you confirm you're using a vanilla kernel? Also I guess the ppp devices and tc settings are handled by accel-ppp. If so, can you share more info about your setup (accel-ppp.conf, radius attributes, iptables...) so that I can try to reproduce it on my machines? Regards Guillaume
