>From a kernel perspective this big slowness on shutting down a bcache volume might be caused by a locking / race condition issue. If I read correctly this problem has been reproduced in bionic (and in xenial we even got a kernel oops - it looks like caused by a NULL pointer dereference). I would try to address these issues separately.
About bionic it would be nice to test this commit (also mentioned by @elmo in comment #28): https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=eb8cbb6df38f6e5124a3d5f1f8a3dbf519537c60 Moreover, even if we didn't get an explicit NULL pointer dereference with bionic, I think it would be interesting to test also the following fixes: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a4b732a248d12cbdb46999daf0bf288c011335eb https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1f0ffa67349c56ea54c03ccfd1e073c990e7411e https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9951379b0ca88c95876ad9778b9099e19a95d566 I've already backported all of them and applied to the latest bionic kernel. A test kernel is available here: https://kernel.ubuntu.com/~arighi/LP-1796292/ If it doesn't cost too much it would be great to do a test with it. In the meantime I'll try to reproduce the problem locally. Thanks in advance! -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1796292 Title: Tight timeout for bcache removal causes spurious failures Status in curtin: Fix Released Status in linux package in Ubuntu: Confirmed Status in linux source package in Bionic: New Status in linux source package in Cosmic: New Status in linux source package in Disco: New Status in linux source package in Eoan: Confirmed Bug description: I've had a number of deployment faults where curtin would report Timeout exceeded for removal of /sys/fs/bcache/xxx when doing a mass- deployment of 30+ nodes. Upon retrying the node would usually deploy fine. Experimentally I've set the timeout ridiculously high, and it seems I'm getting no faults with this. I'm wondering if the timeout for removal is set too tight, or might need to be made configurable. --- curtin/util.py~ 2018-05-18 18:40:48.000000000 +0000 +++ curtin/util.py 2018-10-05 09:40:06.807390367 +0000 @@ -263,7 +263,7 @@ return _subp(*args, **kwargs) -def wait_for_removal(path, retries=[1, 3, 5, 7]): +def wait_for_removal(path, retries=[1, 3, 5, 7, 1200, 1200]): if not path: raise ValueError('wait_for_removal: missing path parameter') To manage notifications about this bug go to: https://bugs.launchpad.net/curtin/+bug/1796292/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
