Am 24.03.2016 um 13:24 schrieb Brian Foster: > On Thu, Mar 24, 2016 at 01:17:15PM +0100, Stefan Priebe - Profihost AG wrote: >> >> Am 24.03.2016 um 12:17 schrieb Brian Foster: >>> On Thu, Mar 24, 2016 at 09:15:15AM +0100, Stefan Priebe - Profihost AG wrote: >>>> >>>> Am 24.03.2016 um 09:10 schrieb Stefan Priebe - Profihost AG: >>>>> >>>>> Am 23.03.2016 um 15:07 schrieb Brian Foster: >>>>>> On Wed, Mar 23, 2016 at 02:28:03PM +0100, Stefan Priebe - Profihost AG wrote: >>>>>>> sorry new one the last one got mangled. Comments inside. >>>>>>> >>>>>>> Am 05.03.2016 um 23:48 schrieb Dave Chinner: >>>>>>>> On Fri, Mar 04, 2016 at 04:03:42PM -0500, Brian Foster wrote: >>>>>>>>> On Fri, Mar 04, 2016 at 09:02:06PM +0100, Stefan Priebe wrote: >>>>>>>>>> Am 04.03.2016 um 20:13 schrieb Brian Foster: >>>>>>>>>>> On Fri, Mar 04, 2016 at 07:47:16PM +0100, Stefan Priebe wrote: >>>>>>>>>>>> Am 20.02.2016 um 19:02 schrieb Stefan Priebe - Profihost AG: >>>>>>>>>>>>> >>>>>>>>>>>>>> Am 20.02.2016 um 15:45 schrieb Brian Foster <bfoster@xxxxxxxxxx>: >>>>>>>>>>>>>> >>>>>>>>>>>>>>> On Sat, Feb 20, 2016 at 09:02:28AM +0100, Stefan Priebe wrote: >>>>>> ... >>>>>>> >>>>>>> This has happened again on 8 different hosts in the last 24 hours >>>>>>> running 4.4.6. >>>>>>> >>>>>>> All of those are KVM / Qemu hosts and are doing NO I/O except the normal >>>>>>> OS stuff as the VMs have remote storage. So no database, no rsync on >>>>>>> those hosts - just the OS doing nearly nothing. >>>>>>> >>>>>>> All those show: >>>>>>> [153360.287040] WARNING: CPU: 0 PID: 109 at fs/xfs/xfs_aops.c:1234 >>>>>>> xfs_vm_releasepage+0xe2/0xf0() >>>>>>> >>>>>> >>>>>> Ok, well at this point the warning isn't telling us anything beyond >>>>>> you're reproducing the problem. We can't really make progress without >>>>>> more information. We don't necessarily know what application or >>>>>> operations caused this by the time it occurs, but perhaps knowing what >>>>>> file is affected could give us a hint. >>>>>> >>>>>> We have the xfs_releasepage tracepoint, but that's unconditional and so >>>>>> might generate a lot of noise by default. Could you enable the >>>>>> xfs_releasepage tracepoint and hunt for instances where delalloc != 0? >>>>>> E.g., we could leave a long running 'trace-cmd record -e >>>>>> "xfs:xfs_releasepage" <cmd>' command on several boxes and wait for the >>>>>> problem to occur. Alternatively (and maybe easier), run 'trace-cmd start >>>>>> -e "xfs:xfs_releasepage"' and leave something like 'cat >>>>>> /sys/kernel/debug/tracing/trace_pipe | grep -v "delalloc 0" > >>>>>> ~/trace.out' running to capture instances. >>>> >>>> Isn't the trace a WARN_ONCE? So it does not reoccur or can i check the >>>> it in the trace.out even the WARN_ONCE was already triggered? >>>> >>> >>> The tracepoint is independent from the warning (see >>> xfs_vm_releasepage()), so the tracepoint will fire every invocation of >>> the function regardless of whether delalloc blocks still exist at that >>> point. That creates the need to filter the entries. >>> >>> With regard to performance, I believe the tracepoints are intended to be >>> pretty lightweight. I don't think it should hurt to try it on a box, >>> observe for a bit and make sure there isn't a huge impact. Note that the >>> 'trace-cmd record' approach will save everything to file, so that's >>> something to consider I suppose. >> >> Tests / cat is running. Is there any way to test if it works? Or is it >> enough that cat prints stuff from time to time but does not match -v >> delalloc 0 >> > > What is it printing where delalloc != 0? You could always just cat > trace_pipe and make sure the event is firing, it's just that I suspect > most entries will have delalloc == unwritten == 0. > > Also, while the tracepoint fires independent of the warning, it might > not be a bad idea to restart a system that has already seen the warning > since boot, just to provide some correlation or additional notification > when the problem occurs. I still wasn't able to catch one with trace-cmd. But i notice that it happens mostly in the first 48hours after a reboot. All systems running since some days but noone triggers this again. All systems who have triggered this bug got rebootet. Stefan -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
