On Jan 5, 2012, at 5:44 AM, Zdenek Kabelac wrote: > Dne 4.1.2012 23:50, David Shaw napsal(a): >> Hi, >> >> I'm using some code that creates a snapshot using DM directly (we aren't using LVM), using essentially: >> >> suspend linear device X >> reload X as a "snapshot-origin" device >> create "snapshot" device >> resume original X device (which is now a snapshot-origin) >> >> This has worked fine for several years. Recently, however, we updated to a more recent system, and ext4, and are seeing something odd. Under load, the process above freezes at the first suspend step, and locks up the device in question, requiring a reboot to fix things. >> >> I wrote the attached program to demonstrate the problem. All it does it call DM_DEVICE_SUSPEND and DM_DEVICE_RESUME over and over on a DM device. Basically, run the test program on any mounted linear DM target in one shell, then delete a lot of data from a directory residing on that device in another shell. On my systems this will freeze both the test program and the rm in D state, and require a reboot to fix things. >> >> I've tried multiple different kernels, but at the moment, I'm using kernel-PAE-2.6.35.6-45.fc14.i686 and device-mapper-libs-1.02.63-2.fc14.i686. >> >> One clue I can add is that it only seems to happen if the filesystem on the device is ext4. It does not happen with ext3. >> >> Any ideas on where I should look next? >> > > Maybe you should suspect ext4 - if there is no problem with dm & ext3 ? > > I guess you need to get stacktrace where the system locks. > (echo t >/proc/sysrq-trigger - or Sysrq+T) > > You should probably also try different kernel. Thanks for the tip! It did indeed turn out to be ext4, and it was already fixed: http://git.kernel.org/?p=linux/kernel/git/stable/linux -stable.git;a=commitdiff;h=be4f27d324e8ddd57cc0d4d604fe85ee0425cba9 David _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
