Re: generic/095 failing in ext4 and xfs

[Luis Henriques <lhenriques@suse.de>]

On Sat, Oct 02, 2021 at 08:59:57AM -0600, Jens Axboe wrote:
> On 10/2/21 4:16 AM, Luis Henriques wrote:
> > "Theodore Ts'o" <tytso@mit.edu> writes:
> > 
> >> On Fri, Oct 01, 2021 at 02:46:09PM -0600, Jens Axboe wrote:
> >>>
> >>> Hmm, do older versions fail? I see Ted suggested that 3.27 doesn't, can
> >>> you give that a go? If that does work, would be great if you could try
> >>> and bisect it.
> >>
> >> I just tried fio 3.28, and it worked for me.  So I don't think it's
> >> fio.
> > 
> > Awesome, thank you both for checking it out.  So, it's definitely
> > something in my test environment.
> > 
> >> Luis, could it be related to a  kernel config option?
> > 
> > Yeah, it could be.  I've tested this on a rolling release (openSUSE TW),
> > so it's definitely quite different from Debian 10.  It may take me a bit
> > to figure out what's going on, but I'll start with this kernel config and
> > report back any finding.
> > 
> > Again, thank you both for confirming it's working on your side.
> 
> Do you have a core file from fio? Would be interesting to get a
> backtrace from it.

Ok, not a lot of progress from my end yet, but here's some info gathered
with gdb from the core file:

#0  0x000056505966b361 in io_completed (td=0x7f2b0c5437a0, io_u_ptr=0x7ffec2403e48, icd=0x7ffec2403e60) at /usr/src/debug/fio-3.28-1.1.x86_64/io_u.c:2012
#1  0x000056505966b922 in ios_completed (icd=0x7ffec2403e60, td=0x7f2b0c5437a0) at /usr/src/debug/fio-3.28-1.1.x86_64/io_u.c:2086
#2  io_u_queued_complete (td=0x7f2b0c5437a0, min_evts=<optimized out>) at /usr/src/debug/fio-3.28-1.1.x86_64/io_u.c:2145
#3  0x0000565059680e88 in do_io (td=0x7f2b0c5437a0, bytes_done=0x7ffec2404070) at /usr/src/debug/fio-3.28-1.1.x86_64/backend.c:1176
#4  0x000056505968a8ee in thread_main (data=data@entry=0x56505ae43510) at /usr/src/debug/fio-3.28-1.1.x86_64/backend.c:1870
#5  0x000056505968ca48 in run_threads (sk_out=0x0) at /usr/src/debug/fio-3.28-1.1.x86_64/backend.c:2460
#6  0x000056505968cb55 in fio_backend (sk_out=0x0) at /usr/src/debug/fio-3.28-1.1.x86_64/backend.c:2597
#7  fio_backend (sk_out=0x0) at /usr/src/debug/fio-3.28-1.1.x86_64/backend.c:2558
#8  0x000056505962fd97 in main (argc=4, argv=0x7ffec240c448, envp=<optimized out>) at /usr/src/debug/fio-3.28-1.1.x86_64/fio.c:60

And here's the io_completed() code where the crash occurs:

   2007                 if (io_u->resid) {
   2008                         io_u->xfer_buflen = io_u->resid;
   2009                         io_u->xfer_buf += bytes;
   2010                         io_u->offset += bytes;
   2011                         td->ts.short_io_u[io_u->ddir]++;
   2012                         if (io_u->offset < io_u->file->real_file_size) {
   2013                                 requeue_io_u(td, io_u_ptr);
   2014                                 return;
   2015                         }
   2016                 }

> In terms of why it's failing, a guess would be that your device is using 4k
> sectors and the test is trying to do 1k aligned dio. That would fail, but
> it should not cause fio to crash...
> 
> -- 
> Jens Axboe
> 

Cheers,
--
Luís