Re: Kernel Panic in skb_release_data using genet

Florian Fainelli
2022-05-14T16:35:52Z

On 5/13/2022 7:56 AM, Maxime Ripard wrote:
> Hi Florian,
>
> Sorry for reviving this old thread...
>
> On Thu, Jun 10, 2021 at 02:33:17PM -0700, Florian Fainelli wrote:
>> On 6/2/2021 6:28 AM, Maxime Ripard wrote:
>>> On Tue, Jun 01, 2021 at 11:33:18AM +0200, nicolas saenz julienne wrote:
>>>> On Mon, 2021-05-31 at 19:36 -0700, Florian Fainelli wrote:
>>>>>> That is also how I boot my Pi4 at home, and I suspect you are right, if
>>>>>> the VPU does not shut down GENET's DMA, and leaves buffer addresses in
>>>>>> the on-chip descriptors that point to an address space that is managed
>>>>>> totally differently by Linux, then we can have a serious problem and
>>>>>> create some memory corruption when the ring is being reclaimed. I will
>>>>>> run a few experiments to test that theory and there may be a solution
>>>>>> using the SW_INIT reset controller to have a big reset of the controller
>>>>>> before handing it over to the Linux driver.
>>>>>
>>>>> Adding a WARN_ON(reg & DMA_EN) in bcmgenet_dma_disable() has not shown
>>>>> that the TX or RX DMA have been left running during the hand over from
>>>>> the VPU to the kernel. I checked out drm-misc-next-2021-05-17 to reduce
>>>>> as much as possible the differences between your set-up and my set-up
>>>>> but so far have not been able to reproduce the crash in booting from NFS
>>>>> repeatedly, I will try again.
>>>>
>>>> FWIW I can reproduce the error too. That said it's rather hard to reproduce,
>>>> something in the order of 1 failure every 20 tries.
>>>
>>> Yeah, it looks like it's only from a cold boot and comes in "bursts",
>>> where you would get like 5 in a row and be done with it for a while.
>>
>> Here are two patches that you could try exclusive from one another
>>
>> 1) Limit GENET to a single queue
>>
>> diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
>> b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
>> index fcca023f22e5..e400c12e6868 100644
>> --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
>> +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
>> @@ -3652,6 +3652,12 @@ static int bcmgenet_change_carrier(struct
>> net_device *dev, bool new_carrier)
>> return 0;
>> }
>>
>> +static u16 bcmgenet_select_queue(struct net_device *dev, struct sk_buff
>> *skb,
>> + struct net_device *sb_dev)
>> +{
>> + return 0;
>> +}
>> +
>> static const struct net_device_ops bcmgenet_netdev_ops = {
>> .ndo_open = bcmgenet_open,
>> .ndo_stop = bcmgenet_close,
>> @@ -3666,6 +3672,7 @@ static const struct net_device_ops
>> bcmgenet_netdev_ops = {
>> #endif
>> .ndo_get_stats = bcmgenet_get_stats,
>> .ndo_change_carrier = bcmgenet_change_carrier,
>> + .ndo_select_queue = bcmgenet_select_queue,
>> };
>>
>> /* Array of GENET hardware parameters/characteristics */
>>
>> 2) Ensure that all TX/RX queues are disabled upon DMA initialization
>>
>> diff --git a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
>> b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
>> index fcca023f22e5..7f8a5996fbbb 100644
>> --- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
>> +++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
>> @@ -3237,15 +3237,21 @@ static void bcmgenet_get_hw_addr(struct
>> bcmgenet_priv *priv,
>> /* Returns a reusable dma control register value */
>> static u32 bcmgenet_dma_disable(struct bcmgenet_priv *priv)
>> {
>> + unsigned int i;
>> u32 reg;
>> u32 dma_ctrl;
>>
>> /* disable DMA */
>> dma_ctrl = 1 << (DESC_INDEX + DMA_RING_BUF_EN_SHIFT) | DMA_EN;
>> + for (i = 0; i < priv->hw_params->tx_queues; i++)
>> + dma_ctrl |= (1 << (i + DMA_RING_BUF_EN_SHIFT));
>> reg = bcmgenet_tdma_readl(priv, DMA_CTRL);
>> reg &= ~dma_ctrl;
>> bcmgenet_tdma_writel(priv, reg, DMA_CTRL);
>>
>> + dma_ctrl = 1 << (DESC_INDEX + DMA_RING_BUF_EN_SHIFT) | DMA_EN;
>> + for (i = 0; i < priv->hw_params->rx_queues; i++)
>> + dma_ctrl |= (1 << (i + DMA_RING_BUF_EN_SHIFT));
>> reg = bcmgenet_rdma_readl(priv, DMA_CTRL);
>> reg &= ~dma_ctrl;
>> bcmgenet_rdma_writel(priv, reg, DMA_CTRL);
>
> It looks like current upstream still has this issue, which also upsets KASAN:
>
> [ 16.798433] ==================================================================
> [ 16.809347] BUG: KASAN: wild-memory-access in skb_release_data+0x124/0x270
> [ 16.816379] Read of size 8 at addr 80800000807f2e0c by task swapper/0/0
> [ 16.823122]
> [ 16.824655] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.18.0-rc5-v8+ #210
> [ 16.831581] Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT)
> [ 16.837525] Call trace:
> [ 16.840025] dump_backtrace.part.0+0x1dc/0x1f0
> [ 16.844576] show_stack+0x24/0x80
> [ 16.847974] dump_stack_lvl+0x8c/0xb8
> [ 16.851735] print_report+0x1cc/0x240
> [ 16.855494] kasan_report+0xb4/0x120
> [ 16.859161] __asan_load8+0xa0/0xc4
> [ 16.862743] skb_release_data+0x124/0x270
> [ 16.866849] consume_skb+0x74/0xe0
> [ 16.870337] __dev_kfree_skb_any+0x74/0x90
> [ 16.874538] bcmgenet_desc_rx+0x4b4/0x620
> [ 16.878642] bcmgenet_rx_poll+0x78/0x150
> [ 16.882657] __napi_poll.constprop.0+0x64/0x240
> [ 16.887290] net_rx_action+0x4d4/0x590
> [ 16.891127] __do_softirq+0x228/0x4d8
> [ 16.894875] __irq_exit_rcu+0x1e4/0x24c
> [ 16.898806] irq_exit_rcu+0x20/0x54
> [ 16.902382] el1_interrupt+0x38/0x50
> [ 16.906051] el1h_64_irq_handler+0x18/0x2c
> [ 16.910250] el1h_64_irq+0x64/0x68
> [ 16.913733] arch_local_irq_enable+0xc/0x20
> [ 16.918010] default_idle_call+0x80/0x114
> [ 16.922118] cpuidle_idle_call+0x1e0/0x224
> [ 16.926310] do_idle+0x104/0x14c
> [ 16.929616] cpu_startup_entry+0x34/0x3c
> [ 16.933630] rest_init+0x180/0x200
> [ 16.937113] arch_post_acpi_subsys_init+0x0/0x30
> [ 16.941840] start_kernel+0x3c8/0x400
> [ 16.945592] __primary_switched+0xa8/0xb0
> [ 16.949699] ==================================================================
> [ 16.957052] Disabling lock debugging due to kernel taint
> [ 16.962507] Unable to handle kernel paging request at virtual address 80800000807f2e0c
> [ 16.970590] Mem abort info:
> [ 16.973461] ESR = 0x96000004
> [ 16.976602] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 16.982038] SET = 0, FnV = 0
> [ 16.985176] EA = 0, S1PTW = 0
> [ 16.988403] FSC = 0x04: level 0 translation fault
> [ 16.993440] Data abort info:
> [ 16.996401] ISV = 0, ISS = 0x00000004
> [ 17.000333] CM = 0, WnR = 0
> [ 17.003384] [80800000807f2e0c] address between user and kernel address ranges
> [ 17.010674] Internal error: Oops: 96000004 [#1] SMP
> [ 17.015651] Modules linked in:
> [ 17.018784] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G B 5.18.0-rc5-v8+ #210
> [ 17.027115] Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT)
> [ 17.033052] pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 17.040148] pc : skb_release_data+0x124/0x270
> [ 17.044603] lr : skb_release_data+0x124/0x270
> [ 17.049055] sp : ffffffc00a477690
> [ 17.052434] x29: ffffffc00a477690 x28: 0000000000000000 x27: ffffff8043cfeb42
> [ 17.059744] x26: 0000000000000001 x25: ffffff8040a5d5be x24: 00000000ffffffff
> [ 17.067049] x23: ffffff8043cfeb40 x22: 0000000000000000 x21: ffffff8040a5d540
> [ 17.074355] x20: ffffff8043cfeb70 x19: 80800000807f2e04 x18: 00000000ee6397dc
> [ 17.081661] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> [ 17.088961] x14: 0000000000000000 x13: 746e696174206c65 x12: ffffffb801567cf9
> [ 17.096265] x11: 1ffffff801567cf8 x10: ffffffb801567cf8 x9 : dfffffc000000000
> [ 17.103572] x8 : ffffffc00ab3e7c7 x7 : 0000000000000001 x6 : ffffffb801567cf8
> [ 17.110875] x5 : ffffffc00ab3e7c0 x4 : ffffffb801567cf9 x3 : 0000000000000000
> [ 17.118178] x2 : 0000000000000020 x1 : ffffffc00a48e7c0 x0 : 0000000000000001
> [ 17.125481] Call trace:
> [ 17.127978] skb_release_data+0x124/0x270
> [ 17.132083] consume_skb+0x74/0xe0
> [ 17.135567] __dev_kfree_skb_any+0x74/0x90
> [ 17.139764] bcmgenet_desc_rx+0x4b4/0x620
> [ 17.143863] bcmgenet_rx_poll+0x78/0x150
> [ 17.147873] __napi_poll.constprop.0+0x64/0x240
> [ 17.152503] net_rx_action+0x4d4/0x590
> [ 17.156338] __do_softirq+0x228/0x4d8
> [ 17.160083] __irq_exit_rcu+0x1e4/0x24c
> [ 17.164008] irq_exit_rcu+0x20/0x54
> [ 17.167580] el1_interrupt+0x38/0x50
> [ 17.171247] el1h_64_irq_handler+0x18/0x2c
> [ 17.175444] el1h_64_irq+0x64/0x68
> [ 17.178923] arch_local_irq_enable+0xc/0x20
> [ 17.183197] default_idle_call+0x80/0x114
> [ 17.187301] cpuidle_idle_call+0x1e0/0x224
> [ 17.191490] do_idle+0x104/0x14c
> [ 17.194793] cpu_startup_entry+0x34/0x3c
> [ 17.198803] rest_init+0x180/0x200
> [ 17.202283] arch_post_acpi_subsys_init+0x0/0x30
> [ 17.207006] start_kernel+0x3c8/0x400
> [ 17.210755] __primary_switched+0xa8/0xb0
> [ 17.214872] Code: 72001c1f 540001e1 91002260 97d3086f (f9400660)
> [ 17.221083] ---[ end trace 0000000000000000 ]---
> [ 17.225791] Kernel panic - not syncing: Oops: Fatal exception in interrupt
> [ 17.232785] SMP: stopping secondary CPUs
> [ 17.236795] Kernel Offset: disabled
> [ 17.240348] CPU features: 0x100,00000d08,00001086
> [ 17.245143] Memory Limit: none
> [ 17.248273] ---[ end Kernel panic - not syncing: Oops: Fatal exception in interrupt ]---
>
> This is at boot, over TFTP and NFS on a RaspberryPi4

How do I reproduce this reliably? What version of GCC did you build your
kernel with? How often does that happen? What config.txt file are you
using for your Pi4 B?
--
Florian