Re: Data corruption in kernel 5.1+ with iSER attached ramdisk

Ming Lei
2019-12-04T23:02:48Z

On Wed, Dec 04, 2019 at 12:23:39PM -0500, Stephen Rust wrote:
> Hi Ming,
>
> I have tried your latest "workaround" patch in brd including the fix
> for large offsets, and it does appear to work. I tried the same tests
> and the data was written correctly for all offsets I tried. Thanks!
>
> I include the updated additional bpftrace below.
>
> > So firstly, I'd suggest to investigate from RDMA driver side to see why
> > un-aligned buffer is passed to block layer.
> >
> > According to previous discussion, 512 aligned buffer should be provided
> > to block layer.
> >
> > So looks the driver needs to be fixed.
>
> If it does appear to be an RDMA driver issue, do you know who we
> should follow up with directly from the RDMA driver side of the world?
>
> Presumably non-brd devices, ie: real scsi devices work for these test
> cases because they accept un-aligned buffers?

Right, not every driver supports such un-aligned buffer.

I am not familiar with RDMA, but from the trace we have done so far,
it is highly related with iser driver.

Thanks,
Ming