On Wed, Oct 11, 2017 at 07:00:47PM +1100, Dave Chinner wrote: > HI folks, > > I was wondering if anyone else had seen this problem, because it's > got me absolutely stumped. One of my test VMs is having a really > weird livelock in xfs/277. It's getting stuck in an endless loop > burning the entire CPU in a the 277 process (i.e. running bash). > What it is stuck on makes no sense to me, nor does the looping > behaviour, and I can only reproduce it on this one machine. > > The code in question: > > "fsmap" ) > testio=`$XFS_IO_PROG -f -c "fsmap" $testfile 2>&1` > echo $testio | grep -q "Inappropriate ioctl" && \ > _notrun "xfs_io $command support is missing" > Oh, so it looks like you're in _require_xfs_io_command(). I was hunting around for this code in xfs/277. :P > Is pretty simple and obvious - not a lot to go wrong. set -x > shows the last command in the output file to be the fsmap command. > $test_io has about 5000 lines of output in it. > > I did some testing to isolate the problem. This exits having > executed the fsmap command just fine: > > > "fsmap" ) > testio=`$XFS_IO_PROG -f -c "fsmap" $testfile 2>&1` > exit > > But this never exits and it starts burning down teh CPU: > > "fsmap" ) > testio=`$XFS_IO_PROG -f -c "fsmap" $testfile 2>&1` > echo $testio > exit > > Yeah, echoing the output of the fsmap command seems to cause bash to > enter an endless loop of some kind. Well, it's not endless, because > every 30s or so the process dies and a new child process runs the > same loop again. Attaching strace to one of these processes: > ... > > bash is running around in a tight loop running readdir() on some > unknown directory over and over again. I can't work it out - this is > the only machine that does it, and it I can't reproduce it outside > of running xfs/277 from xfstests... > > I'm outta ideas - I've got no idea what the hell is going wrong > here. Anyone got any ideas? > Heh, that sounds pretty strange. Does your test dev have a pre-existing $testfile? Have you tried to execute the associated code in an independent bash script? E.g., I'd probably try to do something like mount your test dev then run: XFS_IO_PROG=... testfile=... testio=`$XFS_IO_PROG -f -c "fsmap" $testfile 2>&1` echo $testio ... from a separate script using hardcoded values from the xfstests environment, and see what happens..? Brian > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx > -- > To unsubscribe from this list: send the line "unsubscribe fstests" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe fstests" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
