On Fri, May 16, 2014 at 10:11:56AM +1000, Dave Chinner wrote: > On Fri, May 16, 2014 at 01:19:09AM +0200, Mateusz Guzik wrote: > > Except there is no log entry if /var got frozen (and this is not an > > imaginary example). > > Freezing the filesystem that the freezing daemon logs to is, well, a > major application architecture fail. Sorry, catering for the lowest > common denominator (i.e. stupidity) is not an valid argument for > adding stuff to the kernel.... >
I'm only saying what you can encounter in varous companies. If aiding this problem the way I proposed is not a good idea (and it turns out there is a much better way), I'm not insisting. > > Grabbig a debugger to inspect daemon's state is not > > exactly what your typical support associate can or should do. > > No, but they can read /proc/self/mountinfo, and grab sysrq-w output. > And they should be able to read that and tell that there is a freeze > hang from that info. This "filesystem hang triage 101" stuff.... > > > But this was a side request, I'm not going to argue about including > > this since turns out there is a better way. > > > > Somewhere in the thread an idea to log long-standing freezes was > > mentioned which would provide sufficient information as far as > > You've already got the hung task timer firing when a fs is frozen > for too long. You'll see processes hung in sb_write_wait(), and that > tells you the filesystem is frozen. Then look at > /proc/self/mountinfo to find which fs is frozen.... > But additional question was what initiated the freeze and it is not answered by this. Hopefully a warning for long-standing freezes will be implemented and that will answer the question. Once more, I'm fine with mere 'frozen' in mountinfo, so I suggest we drop this now side subject. If you really want to continue we can discuss this in private. :-> -- Mateusz Guzik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
