WARNING: CPU: 0 PID: 0 at net/core/skbuff.c:3995

[simonhiggs]

Hello All, I hope I've posted in the right place...

I've just installed Arch on a Raspberry Pi 2, for use with squeezelite audio software and an HiFiBerry SPDIF interface.
All is working well, except occasionally I have a loud noise from the interface for a couple of seconds. There is this entry in dmesg..

$this->bbcode_second_pass_code('', '[ 238.294945] ------------[ cut here ]------------
[ 238.299968] WARNING: CPU: 0 PID: 0 at net/core/skbuff.c:3995 skb_try_coalesce+0x320/0x378()
[ 238.308804] Modules linked in: snd_soc_bcm2708_i2s snd_soc_wm8804 snd_soc_hifiberry_digi regmap_mmio snd_soc_core snd_compress snd_pcm_dmaengine snd_pcm snd_timer regmap_spi regmap_i2c snd leds_gpio led_class i2c_bcm2708 uio_pdrv_genirq uio sch_fq_codel bcm2708_rng rng_core ipv6
[ 238.334535] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.18.7-3-ARCH #1
[ 238.341237] [<c0015630>] (unwind_backtrace) from [<c0011f2c>] (show_stack+0x10/0x14)
[ 238.349209] [<c0011f2c>] (show_stack) from [<c0734b44>] (dump_stack+0x84/0xc4)
[ 238.356608] [<c0734b44>] (dump_stack) from [<c002ca84>] (warn_slowpath_common+0x74/0x90)
[ 238.364884] [<c002ca84>] (warn_slowpath_common) from [<c002cb3c>] (warn_slowpath_null+0x1c/0x24)
[ 238.373854] [<c002cb3c>] (warn_slowpath_null) from [<c065db4c>] (skb_try_coalesce+0x320/0x378)
[ 238.382662] [<c065db4c>] (skb_try_coalesce) from [<c06b2108>] (tcp_try_coalesce.part.38+0x28/0xbc)
[ 238.391811] [<c06b2108>] (tcp_try_coalesce.part.38) from [<c06b38dc>] (tcp_data_queue+0x7a8/0xca8)
[ 238.400956] [<c06b38dc>] (tcp_data_queue) from [<c06b55d0>] (tcp_rcv_established+0x150/0x63c)
[ 238.426714] [<c06b55d0>] (tcp_rcv_established) from [<c06bd998>] (tcp_v4_do_rcv+0x180/0x394)
[ 238.470670] [<c06bd998>] (tcp_v4_do_rcv) from [<c06c01a4>] (tcp_v4_rcv+0x8c4/0x8cc)
[ 238.514735] [<c06c01a4>] (tcp_v4_rcv) from [<c069c830>] (ip_local_deliver_finish+0xe0/0x2c8)
[ 238.559597] [<c069c830>] (ip_local_deliver_finish) from [<c0667f9c>] (__netif_receive_skb_core+0x664/0x85c)
[ 238.605725] [<c0667f9c>] (__netif_receive_skb_core) from [<c066b8d8>] (process_backlog+0x8c/0x138)
[ 238.651234] [<c066b8d8>] (process_backlog) from [<c066b71c>] (net_rx_action+0x13c/0x26c)
[ 238.696117] [<c066b71c>] (net_rx_action) from [<c00303f4>] (__do_softirq+0x128/0x320)
[ 238.741185] [<c00303f4>] (__do_softirq) from [<c0030880>] (irq_exit+0xb8/0xf4)
[ 238.767215] [<c0030880>] (irq_exit) from [<c0073508>] (__handle_domain_irq+0xa8/0x104)
[ 238.812251] [<c0073508>] (__handle_domain_irq) from [<c073a830>] (__irq_svc+0x30/0x144)
[ 238.857412] [<c073a830>] (__irq_svc) from [<c000f13c>] (arch_cpu_idle+0x38/0x3c)
[ 238.901788] [<c000f13c>] (arch_cpu_idle) from [<c0064528>] (cpu_startup_entry+0x358/0x3e4)
[ 238.947059] [<c0064528>] (cpu_startup_entry) from [<c09f7c64>] (start_kernel+0x3a0/0x3ac)
[ 238.992133] ---[ end trace ac9dbc156bde2360 ]---')

I've no idea about what this means, let alone how to fix. Any help most welcome.

Simon.

[moonman]

Looks like a bug in the kernel or the driver for your NIC. I would report to RPI foundation directly. https://github.com/raspberrypi/linux/issues as we are using same source

[simonhiggs]

Thanks moonman,

Now posted over at RPi..

Simon.