On Tue, 23 Feb 2021 10:28:35 +0200
Tariq Toukan <ttoukan.li...@gmail.com> wrote:
> On 2/22/2021 9:50 PM, Jesper Dangaard Brouer wrote:
> > Net-next at commit d310ec03a34e ("Merge tag 'perf-core-2021-02-17')
> >
> > There is a divide error in drivers/net/ethernet/mellanox/mlx5/core/en_tx.c
> > where it seems that num_tc_x_num_ch can become zero in a modulo operation:
> >
> > if (unlikely(txq_ix >= num_tc_x_num_ch))
> > txq_ix %= num_tc_x_num_ch;
> >
> > I think error were introduced in:
> > - 214baf22870c ("net/mlx5e: Support HTB offload")
> >
> > The modulo operation was introduced in:
> > - 145e5637d941 ("net/mlx5e: Add TX PTP port object support")
> >
> > The crash looks like this:
> >
> > [ 12.112849] divide error: 0000 [#1] PREEMPT SMP PTI
> > [ 12.117727] CPU: 4 PID: 0 Comm: swapper/4 Not tainted 5.11.0-net-next+
> > #575
> > [ 12.124677] Hardware name: Supermicro Super Server/X10SRi-F, BIOS 2.0a
> > 08/01/2016
> > [ 12.132149] RIP: 0010:mlx5e_select_queue+0xd5/0x1e0 [mlx5_core]
> > [ 12.138110] Code: 85 c0 75 2e 48 83 bb 08 57 00 00 00 75 5b 31 d2 48 89
> > ee 48 89 df e8 ba 3e 54 e1 0f b7 d0 41 39 d4 0f 8f 6b ff ff ff 89 d0 99
> > <41> f7 fc e9 60 ff ff ff 8b 96 8c 00 00 00 89 d1 c1 e9 10 39 c1 0f
> > [ 12.156849] RSP: 0018:ffffc900001c0c10 EFLAGS: 00010297
> > [ 12.162065] RAX: 0000000000000004 RBX: ffff88810ff00000 RCX:
> > 0000000000000007
> > [ 12.169188] RDX: 0000000000000000 RSI: ffff888107016400 RDI:
> > ffff8881008dc740
> > [ 12.176313] RBP: ffff888107016400 R08: 0000000000000000 R09:
> > 000000ncing: Fatal exception in interrupt ]---
> >
> > This is an RFC, because I don't think this is a proper fix, but
> > at least it allows me to boot with mlx5 driver enabled.
> >
> > Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
> > ---
>
> Hi Jesper,
>
> Thanks for your report and patch.
>
> We'll check it and post the proper fix.
> I wonder what's special in your configuration / use case, as I'm not
> aware of such failure.
> Can you please share more info about the reproduction?
The machine simply crash under boot, that is how I reproduced.
You should look at why: num_tc_x_num_ch can be zero in:
u16 mlx5e_select_queue(struct net_device *dev, struct sk_buff *skb,
struct net_device *sb_dev)
{
[...]
num_tc_x_num_ch = READ_ONCE(priv->num_tc_x_num_ch);
Here are some info on the mlx5 NIC I'm using:
$ ethtool -i mlx5p1
driver: mlx5_core
version: 5.11.0-net-next-alloc_pages_bul
firmware-version: 16.23.1020 (MT_0000000009)
expansion-rom-version:
bus-info: 0000:03:00.0
supports-statistics: yes
supports-test: yes
supports-eeprom-access: no
supports-register-dump: no
supports-priv-flags: yes
03:00.0 Ethernet controller: Mellanox Technologies MT28800 Family [ConnectX-5
Ex]
Subsystem: Mellanox Technologies Device 0002
Physical Slot: 0
Flags: bus master, fast devsel, latency 0, IRQ 26
Memory at f0000000 (64-bit, prefetchable) [size=32M]
Expansion ROM at fba00000 [disabled] [size=1M]
Capabilities: [60] Express Endpoint, MSI 00
Capabilities: [48] Vital Product Data
Capabilities: [9c] MSI-X: Enable+ Count=64 Masked-
Capabilities: [c0] Vendor Specific Information: Len=18 <?>
Capabilities: [40] Power Management version 3
Capabilities: [100] Advanced Error Reporting
Capabilities: [150] Alternative Routing-ID Interpretation (ARI)
Capabilities: [1c0] Secondary PCI Express
Capabilities: [230] Access Control Services
Capabilities: [320] Lane Margining at the Receiver <?>
Capabilities: [370] Physical Layer 16.0 GT/s <?>
Capabilities: [420] Data Link Feature <?>
Kernel driver in use: mlx5_core
Kernel modules: mlx5_core
03:00.1 Ethernet controller: Mellanox Technologies MT28800 Family [ConnectX-5
Ex]
Subsystem: Mellanox Technologies Device 0002
Physical Slot: 0
Flags: bus master, fast devsel, latency 0, IRQ 86
Memory at ee000000 (64-bit, prefetchable) [size=32M]
Expansion ROM at fb900000 [disabled] [size=1M]
Capabilities: [60] Express Endpoint, MSI 00
Capabilities: [48] Vital Product Data
Capabilities: [9c] MSI-X: Enable+ Count=64 Masked-
Capabilities: [c0] Vendor Specific Information: Len=18 <?>
Capabilities: [40] Power Management version 3
Capabilities: [100] Advanced Error Reporting
Capabilities: [150] Alternative Routing-ID Interpretation (ARI)
Capabilities: [230] Access Control Services
Capabilities: [420] Data Link Feature <?>
Kernel driver in use: mlx5_core
Kernel modules: mlx5_core
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
