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Message-ID: <20240118081253-mutt-send-email-mst@kernel.org>
Date: Thu, 18 Jan 2024 08:14:21 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Zhu Yanjun <yanjun.zhu@...el.com>, jasowang@...hat.com,
xuanzhuo@...ux.alibaba.com, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org,
virtualization@...ts.linux.dev, netdev@...r.kernel.org,
Zhu Yanjun <yanjun.zhu@...ux.dev>
Subject: Re: [PATCH 1/1] virtio_net: Add timeout handler to avoid kernel hang
On Tue, Jan 16, 2024 at 01:04:49PM +0100, Paolo Abeni wrote:
> On Mon, 2024-01-15 at 09:29 +0800, Zhu Yanjun wrote:
> > From: Zhu Yanjun <yanjun.zhu@...ux.dev>
> >
> > Some devices emulate the virtio_net hardwares. When virtio_net
> > driver sends commands to the emulated hardware, normally the
> > hardware needs time to response. Sometimes the time is very
> > long. Thus, the following will appear. Then the whole system
> > will hang.
> > The similar problems also occur in Intel NICs and Mellanox NICs.
> > As such, the similar solution is borrowed from them. A timeout
> > value is added and the timeout value as large as possible is set
> > to ensure that the driver gets the maximum possible response from
> > the hardware.
> >
> > "
> > [ 213.795860] watchdog: BUG: soft lockup - CPU#108 stuck for 26s! [(udev-worker):3157]
> > [ 213.796114] Modules linked in: virtio_net(+) net_failover failover qrtr rfkill sunrpc intel_rapl_msr intel_rapl_common intel_uncore_frequency intel_uncore_frequency_common intel_ifs i10nm_edac nfit libnvdimm x86_pkg_temp_thermal intel_powerclamp coretemp iTCO_wdt rapl intel_pmc_bxt dax_hmem iTCO_vendor_support vfat cxl_acpi intel_cstate pmt_telemetry pmt_class intel_sdsi joydev intel_uncore cxl_core fat pcspkr mei_me isst_if_mbox_pci isst_if_mmio idxd i2c_i801 isst_if_common mei intel_vsec idxd_bus i2c_smbus i2c_ismt ipmi_ssif acpi_ipmi ipmi_si ipmi_devintf ipmi_msghandler acpi_pad acpi_power_meter pfr_telemetry pfr_update fuse loop zram xfs crct10dif_pclmul crc32_pclmul crc32c_intel polyval_clmulni polyval_generic ghash_clmulni_intel sha512_ssse3 bnxt_en sha256_ssse3 sha1_ssse3 nvme ast nvme_core i2c_algo_bit wmi pinctrl_emmitsburg scsi_dh_rdac scsi_dh_emc scsi_dh_alua dm_multipath
> > [ 213.796194] irq event stamp: 67740
> > [ 213.796195] hardirqs last enabled at (67739): [<ffffffff8c2015ca>] asm_sysvec_apic_timer_interrupt+0x1a/0x20
> > [ 213.796203] hardirqs last disabled at (67740): [<ffffffff8c14108e>] sysvec_apic_timer_interrupt+0xe/0x90
> > [ 213.796208] softirqs last enabled at (67686): [<ffffffff8b12115e>] __irq_exit_rcu+0xbe/0xe0
> > [ 213.796214] softirqs last disabled at (67681): [<ffffffff8b12115e>] __irq_exit_rcu+0xbe/0xe0
> > [ 213.796217] CPU: 108 PID: 3157 Comm: (udev-worker) Kdump: loaded Not tainted 6.7.0+ #9
> > [ 213.796220] Hardware name: Intel Corporation M50FCP2SBSTD/M50FCP2SBSTD, BIOS SE5C741.86B.01.01.0001.2211140926 11/14/2022
> > [ 213.796221] RIP: 0010:virtqueue_get_buf_ctx_split+0x8d/0x110
> > [ 213.796228] Code: 89 df e8 26 fe ff ff 0f b7 43 50 83 c0 01 66 89 43 50 f6 43 78 01 75 12 80 7b 42 00 48 8b 4b 68 8b 53 58 74 0f 66 87 44 51 04 <48> 89 e8 5b 5d c3 cc cc cc cc 66 89 44 51 04 0f ae f0 48 89 e8 5b
> > [ 213.796230] RSP: 0018:ff4bbb362306f9b0 EFLAGS: 00000246
> > [ 213.796233] RAX: 0000000000000000 RBX: ff2f15095896f000 RCX: 0000000000000001
> > [ 213.796235] RDX: 0000000000000000 RSI: ff4bbb362306f9cc RDI: ff2f15095896f000
> > [ 213.796236] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> > [ 213.796237] R10: 0000000000000003 R11: ff2f15095893cc40 R12: 0000000000000002
> > [ 213.796239] R13: 0000000000000004 R14: 0000000000000000 R15: ff2f1509534f3000
> > [ 213.796240] FS: 00007f775847d0c0(0000) GS:ff2f1528bac00000(0000) knlGS:0000000000000000
> > [ 213.796242] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 213.796243] CR2: 0000557f987b6e70 CR3: 0000002098602006 CR4: 0000000000f71ef0
> > [ 213.796245] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > [ 213.796246] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
> > [ 213.796247] PKRU: 55555554
> > [ 213.796249] Call Trace:
> > [ 213.796250] <IRQ>
> > [ 213.796252] ? watchdog_timer_fn+0x1c0/0x220
> > [ 213.796258] ? __pfx_watchdog_timer_fn+0x10/0x10
> > [ 213.796261] ? __hrtimer_run_queues+0x1af/0x380
> > [ 213.796269] ? hrtimer_interrupt+0xf8/0x230
> > [ 213.796274] ? __sysvec_apic_timer_interrupt+0x64/0x1a0
> > [ 213.796279] ? sysvec_apic_timer_interrupt+0x6d/0x90
> > [ 213.796282] </IRQ>
> > [ 213.796284] <TASK>
> > [ 213.796285] ? asm_sysvec_apic_timer_interrupt+0x1a/0x20
> > [ 213.796293] ? virtqueue_get_buf_ctx_split+0x8d/0x110
> > [ 213.796297] virtnet_send_command+0x18a/0x1f0 [virtio_net]
> > [ 213.796310] _virtnet_set_queues+0xc6/0x120 [virtio_net]
> > [ 213.796319] virtnet_probe+0xa06/0xd50 [virtio_net]
> > [ 213.796328] virtio_dev_probe+0x195/0x230
> > [ 213.796333] really_probe+0x19f/0x400
> > [ 213.796338] ? __pfx___driver_attach+0x10/0x10
> > [ 213.796340] __driver_probe_device+0x78/0x160
> > [ 213.796343] driver_probe_device+0x1f/0x90
> > [ 213.796346] __driver_attach+0xd6/0x1d0
> > [ 213.796349] bus_for_each_dev+0x8c/0xe0
> > [ 213.796355] bus_add_driver+0x119/0x220
> > [ 213.796359] driver_register+0x59/0x100
> > [ 213.796362] ? __pfx_virtio_net_driver_init+0x10/0x10 [virtio_net]
> > [ 213.796369] virtio_net_driver_init+0x8e/0xff0 [virtio_net]
> > [ 213.796375] do_one_initcall+0x6f/0x380
> > [ 213.796384] do_init_module+0x60/0x240
> > [ 213.796388] init_module_from_file+0x86/0xc0
> > [ 213.796396] idempotent_init_module+0x129/0x2c0
> > [ 213.796406] __x64_sys_finit_module+0x5e/0xb0
> > [ 213.796409] do_syscall_64+0x60/0xe0
> > [ 213.796415] ? do_syscall_64+0x6f/0xe0
> > [ 213.796418] ? lockdep_hardirqs_on_prepare+0xe4/0x1a0
> > [ 213.796424] ? do_syscall_64+0x6f/0xe0
> > [ 213.796427] ? do_syscall_64+0x6f/0xe0
> > [ 213.796431] entry_SYSCALL_64_after_hwframe+0x6e/0x76
> > [ 213.796435] RIP: 0033:0x7f7758f279cd
> > [ 213.796465] Code: 5d c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 33 e4 0c 00 f7 d8 64 89 01 48
> > [ 213.796467] RSP: 002b:00007ffe2cad8738 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
> > [ 213.796469] RAX: ffffffffffffffda RBX: 0000557f987a8180 RCX: 00007f7758f279cd
> > [ 213.796471] RDX: 0000000000000000 RSI: 00007f77593e5453 RDI: 000000000000000f
> > [ 213.796472] RBP: 00007f77593e5453 R08: 0000000000000000 R09: 00007ffe2cad8860
> > [ 213.796473] R10: 000000000000000f R11: 0000000000000246 R12: 0000000000020000
> > [ 213.796475] R13: 0000557f9879f8e0 R14: 0000000000000000 R15: 0000557f98783aa0
> > [ 213.796482] </TASK>
> > "
> >
> > Signed-off-by: Zhu Yanjun <yanjun.zhu@...ux.dev>
> > ---
> > drivers/net/virtio_net.c | 10 ++++++++--
> > 1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 51b1868d2f22..28b7dd917a43 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -2468,7 +2468,7 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> > {
> > struct scatterlist *sgs[4], hdr, stat;
> > unsigned out_num = 0, tmp;
> > - int ret;
> > + int ret, timeout = 200;
> >
> > /* Caller should know better */
> > BUG_ON(!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ));
> > @@ -2502,8 +2502,14 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> > * into the hypervisor, so the request should be handled immediately.
> > */
> > while (!virtqueue_get_buf(vi->cvq, &tmp) &&
> > - !virtqueue_is_broken(vi->cvq))
> > + !virtqueue_is_broken(vi->cvq)) {
> > + if (timeout)
> > + timeout--;
>
> This is not really a timeout, just a loop counter. 200 iterations could
> be a very short time on reasonable H/W. I guess this avoid the soft
> lockup, but possibly (likely?) breaks the functionality when we need to
> loop for some non negligible time.
>
> I fear we need a more complex solution, as mentioned by Micheal in the
> thread you quoted.
>
> Cheers,
>
> Paolo
So a bunch of devices just queue a rquest on a workqueue. Problem is,
errors are not reported then. I really feel this is something netdev
core should support better: return a "deferred" status and have
netdev core wait outside a lock on a waitqueue.
--
MST
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