DPAA2 triggers, [PATCH] dma debug: report -EEXIST errors in add_dma_entry

Jeremy Linton
2021-09-09T03:34:13Z

+DPAA2, netdev maintainers
Hi,

On 5/18/21 7:54 AM, Hamza Mahfooz wrote:
> Since, overlapping mappings are not supported by the DMA API we should
> report an error if active_cacheline_insert returns -EEXIST.

It seems this patch found a victim. I was trying to run iperf3 on a
honeycomb (5.14.0, fedora 35) and the console is blasting this error
message at 100% cpu. So, I changed it to a WARN_ONCE() to get the call
trace, which is attached below.

[ 151.839693] cacheline tracking EEXIST, overlapping mappings aren't
supported
...
[ 151.924397] Hardware name: SolidRun Ltd. SolidRun CEX7 Platform, BIOS
EDK II Aug 9 2021
[ 151.932481] pstate: 40400005 (nZcv daif +PAN -UAO -TCO BTYPE=--)
[ 151.938483] pc : add_dma_entry+0x218/0x240
[ 151.942575] lr : add_dma_entry+0x218/0x240
[ 151.946666] sp : ffff8000101e2f20
[ 151.949975] x29: ffff8000101e2f20 x28: ffffaf317ac85000 x27:
ffff3d0366ecb3a0
[ 151.957116] x26: 0000040000000000 x25: 0000000000000001 x24:
ffffaf317bbe8908
[ 151.964257] x23: 0000000000000001 x22: ffffaf317bbe8810 x21:
0000000000000000
[ 151.971397] x20: 0000000082e48000 x19: ffffaf317be6e000 x18:
ffffffffffffffff
[ 151.978537] x17: 646574726f707075 x16: 732074276e657261 x15:
ffff8000901e2c2f
[ 151.985676] x14: 0000000000000000 x13: 0000000000000000 x12:
0000000000000000
[ 151.992816] x11: ffffaf317bb4c4c0 x10: 00000000ffffe000 x9 :
ffffaf3179708060
[ 151.999956] x8 : 00000000ffffdfff x7 : ffffaf317bb4c4c0 x6 :
0000000000000001
[ 152.007096] x5 : ffff3d0a9af66e30 x4 : 0000000000000000 x3 :
0000000000000027
[ 152.014236] x2 : 0000000000000023 x1 : ffff3d0360aac000 x0 :
0000000000000040
[ 152.021376] Call trace:
[ 152.023816] add_dma_entry+0x218/0x240
[ 152.027561] debug_dma_map_sg+0x118/0x17c
[ 152.031566] dma_map_sg_attrs+0x70/0xb0
[ 152.035397] dpaa2_eth_build_sg_fd+0xac/0x2f0 [fsl_dpaa2_eth]
[ 152.041150] __dpaa2_eth_tx+0x3ec/0x570 [fsl_dpaa2_eth]
[ 152.046377] dpaa2_eth_tx+0x74/0x110 [fsl_dpaa2_eth]
[ 152.051342] dev_hard_start_xmit+0xe8/0x1a4
[ 152.055523] sch_direct_xmit+0x8c/0x1e0
[ 152.059355] __dev_xmit_skb+0x484/0x6a0
[ 152.063186] __dev_queue_xmit+0x380/0x744
[ 152.067190] dev_queue_xmit+0x20/0x2c
[ 152.070848] neigh_hh_output+0xb4/0x130
[ 152.074679] ip_finish_output2+0x494/0x8f0
[ 152.078770] __ip_finish_output+0x12c/0x230
[ 152.082948] ip_finish_output+0x40/0xe0
[ 152.086778] ip_output+0xe4/0x2d4
[ 152.090088] __ip_queue_xmit+0x1b4/0x5c0
[ 152.094006] ip_queue_xmit+0x20/0x30
[ 152.097576] __tcp_transmit_skb+0x3b8/0x7b4
[ 152.101755] tcp_write_xmit+0x350/0x8e0
[ 152.105586] __tcp_push_pending_frames+0x48/0x110
[ 152.110286] tcp_rcv_established+0x338/0x690
[ 152.114550] tcp_v4_do_rcv+0x1c0/0x29c
[ 152.118294] tcp_v4_rcv+0xd14/0xe3c
[ 152.121777] ip_protocol_deliver_rcu+0x88/0x340
[ 152.126302] ip_local_deliver_finish+0xc0/0x184
[ 152.130827] ip_local_deliver+0x7c/0x23c
[ 152.134744] ip_rcv_finish+0xb4/0x100
[ 152.138400] ip_rcv+0x54/0x210
[ 152.141449] deliver_skb+0x74/0xdc
[ 152.144846] __netif_receive_skb_core.constprop.0+0x250/0x81c
[ 152.150588] __netif_receive_skb_list_core+0x94/0x264
[ 152.155635] netif_receive_skb_list_internal+0x1d0/0x3bc
[ 152.160942] netif_receive_skb_list+0x38/0x70
[ 152.165295] dpaa2_eth_poll+0x168/0x350 [fsl_dpaa2_eth]
[ 152.170521] __napi_poll.constprop.0+0x40/0x19c
[ 152.175047] net_rx_action+0x2c4/0x360
[ 152.178792] __do_softirq+0x1b0/0x394
[ 152.182450] run_ksoftirqd+0x68/0xa0
[ 152.186023] smpboot_thread_fn+0x13c/0x270
[ 152.190115] kthread+0x138/0x140

PS, it might not hurt to rate limit/_once this somehow to avoid a
runtime problem if it starts to trigger.

Thanks,

>
> Suggested-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Hamza Mahfooz <someguy@effective-light.com>
> ---
> kernel/dma/debug.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/dma/debug.c b/kernel/dma/debug.c
> index 14de1271463f..dadae6255d05 100644
> --- a/kernel/dma/debug.c
> +++ b/kernel/dma/debug.c
> @@ -566,11 +566,9 @@ static void add_dma_entry(struct dma_debug_entry *entry)
> if (rc == -ENOMEM) {
> pr_err("cacheline tracking ENOMEM, dma-debug disabled\n");
> global_disable = true;
> + } else if (rc == -EEXIST) {
> + pr_err("cacheline tracking EEXIST, overlapping mappings aren't supported\n");
> }
> -
> - /* TODO: report -EEXIST errors here as overlapping mappings are
> - * not supported by the DMA API
> - */
> }
>
> static int dma_debug_create_entries(gfp_t gfp)