On 12/18/2012 12:05 PM, Nick Bartos wrote: > I've added the output of "ps -ef" in addition to triggering a trace > when a hang is detected. Not much is generally running at that point, > but you can have a look: > > https://gist.github.com/raw/4330223/2f131ee312ee43cb3d8c307a9bf2f454a7edfe57/rbd-hang-1355851498.txt This helped a lot. I updated the bug with a little more info. http://tracker.newdream.net/issues/3519 I also think I have now found something that could explain what you are seeing, and am developing a fix. I'll provide you an update as soon as I have tested what I come up with, almost certainly this afternoon. -Alex > Is it possible that there is some sort of deadlock going on? We are > doing the rbd maps (and subsequent filesystem mounts) on the same > systems which are running the ceph-osd and ceph-mon processes. To get > around the 'sync' deadlock problem, we are using a patch from Sage > which ignores system wide sync's on filesystems mounted with the > 'mand' option (and we mount the underlying osd filesystems with > 'mand'). However I am wondering if there is potential for other types > of deadlocks in this environment. > > Also, we recently saw an rbd hang in a much older version, running > kernel 3.5.3 with only the sync hack patch, along side ceph 0.48.1. > It's possible that this issue was around for some time, just the > recent patches made it happen more often (and thus more reproducible) > for us. > > > On Tue, Dec 18, 2012 at 8:09 AM, Alex Elder <elder@xxxxxxxxxxx> wrote: >> On 12/17/2012 11:12 AM, Nick Bartos wrote: >>> Here's a log with the rbd debugging enabled: >>> >>> https://gist.github.com/raw/4319962/d9690fd92c169198efc5eecabf275ef1808929d2/rbd-hang-test-1355763470.log >>> >>> On Fri, Dec 14, 2012 at 10:03 AM, Alex Elder <elder@xxxxxxxxxxx> wrote: >>>> On 12/14/2012 10:53 AM, Nick Bartos wrote: >>>>> Yes I was only enabling debugging for libceph. I'm adding debugging >>>>> for rbd as well. I'll do a repro later today when a test cluster >>>>> opens up. >>>> >>>> Excellent, thank you. -Alex >> >> I looked through these debugging messages. Looking only at the >> rbd debugging, what I see seems to indicate that rbd is idle at >> the point the "hang" seems to start. This suggests that the hang >> is not due to rbd itself, but rather whatever it is that might >> be responsible for using the rbd image once it has been mapped. >> >> Is that possible? I don't know what process you have that is >> mapping the rbd image, and what is supposed to be the next thing >> it does. (I realize this may not make a lot of sense, given >> a patch in rdb seems to have caused the hang to begin occurring.) >> >> Also note that the debugging information available (i.e., the >> lines in the code that can output debugging information) may >> well be incomplete. So if you don't find anything it may be >> necessary to provide you with another update which might include >> more debugging. >> >> Anyway, could you provide a little more context about what >> is going on sort of *around* rbd when activity seems to stop? >> >> Thanks a lot. >> >> -Alex -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
