Re: [PATCH] sunvdc: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN

Re: [PATCH] sunvdc: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN

[Jens Axboe]

On 11/28/18 5:36 AM, Yang Xiao wrote:
> From: Young Xiao <YangX92@hotmail.com>
> 
> __vdc_tx_trigger should only loop on EAGAIN a finite
> number of times.
> 
> See commit adddc32d6fde ("sunvnet: Do not spin in an
> infinite loop when vio_ldc_send() returns EAGAIN") for detail.

Looks good to me, applied.

-- 
Jens Axboe

Re: [PATCH] sunvdc: Do not spin in an infinite loop when vio_ldc_send() returns EAGAIN

[John Paul Adrian Glaubitz]

Hello Jens and Yang,

On Wed, 2018-11-28 at 06:23 -0700, Jens Axboe wrote:
> On 11/28/18 5:36 AM, Yang Xiao wrote:
> > From: Young Xiao <YangX92@hotmail.com>
> > 
> > __vdc_tx_trigger should only loop on EAGAIN a finite
> > number of times.
> > 
> > See commit adddc32d6fde ("sunvnet: Do not spin in an
> > infinite loop when vio_ldc_send() returns EAGAIN") for detail.
> 
> Looks good to me, applied.

I am seeing a lot of I/O errors as a result of this change of Linux running
inside a SPARC T5-2 LDOM running on Solaris 11.4.81 and I'm wondering whether
this change was justified by the commit in adddc32d6fde ("sunvnet: Do not spin
in an infinite loop when vio_ldc_send() returns EAGAIN") only or whether there
were actual bug reports.

See the output below:

[19095.192532] sunvdc: vdc_tx_trigger() failure, err=-11
[19095.192605] I/O error, dev vdiskc, sector 368208928 op 0x1:(WRITE) flags 0x1000 phys_seg 2 prio class 2
[19095.205681] XFS (vdiskc1): metadata I/O error in "xfs_buf_ioend+0x28c/0x600 [xfs]" at daddr 0x15f26420 len 32 error 5
[19432.043471] sunvdc: vdc_tx_trigger() failure, err=-11
[19432.043529] I/O error, dev vdiskc, sector 3732568 op 0x1:(WRITE) flags 0x1000 phys_seg 1 prio class 2
[19432.058821] sunvdc: vdc_tx_trigger() failure, err=-11
[19432.058843] I/O error, dev vdiskc, sector 3736256 op 0x1:(WRITE) flags 0x1000 phys_seg 4 prio class 2
[19432.074109] sunvdc: vdc_tx_trigger() failure, err=-11
[19432.074128] I/O error, dev vdiskc, sector 3736512 op 0x1:(WRITE) flags 0x1000 phys_seg 4 prio class 2
[19432.089425] sunvdc: vdc_tx_trigger() failure, err=-11
[19432.089443] I/O error, dev vdiskc, sector 3737024 op 0x1:(WRITE) flags 0x1000 phys_seg 1 prio class 2
[19432.100964] XFS (vdiskc1): metadata I/O error in "xfs_buf_ioend+0x28c/0x600 [xfs]" at daddr 0x38ec58 len 8 error 5

At least Oracle's UEK kernel for SPARC [1] does not contain this change which
is why I'm a bit reluctant to believe that the change is correct.

Adrian

> [1] https://github.com/oracle/linux-uek/tree/uek4/qu7/

-- 
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