Appreciate you looking into this, I was only able to test your builds for about 5 hours on generic kernel version so far (doing some hardware upgrades at the moment, but my current test system is torture-test stable).
My test hardware was 2x (westmere) Intel Xeon E5620's (2 NUMA nodes) with 12GB (2GBx6) ECC RDIMMs on each CPU (24GB total) on ubuntu-server 16.04. ztest was ran on default /tmp however I had /tmp mounted on tmpfs with 10G limit, but from what I could tell it was not exceeding that limit. I believe this issue becomes more apparent in 4.4.11 and 4.4.12 (and possibly 4.4.13 now) for some reason since those were failing for me within a few hours with this "fix" applied, whereas latest stable I compiled with fix seemed okay. I think there's some race conditions of some sort with newer kernels, especially since I saw different results on the lowlatency kernel awhile back (on the same stable release). I'll do some more testing if I have some time, and I want to test this on some other distros as well but I think the fix might not work on future kernel releases that integrate 4.4.11, 4.4.12, and 4.4.13 since some of the patches may have changed some core functions which uncovered ZFS bugs again. It's still possible it somehow only effects my hardware/OS only. Unless I was compiling the kernel strangely, I was doing a git clone from master-next, checking out latest stable (detached head) and applying/commiting the patch. My 4.4.11 and 4.4.12 builds were were manually applied cleanly from upstream on top of xenial master-next (neither were merged into master-next at the time), so that could also have been a possible issue - there was a few redundant patches I skipped that were already in master-next though. However, the bug still stands on stock stable xenial kernel - and this patch seems to fix it (at least on generic, still unsure about lowlatency). Compiling debian/ubuntu kernels from git is pretty complicated though with conflicting documentation. I was using this command after checking out and appluing patch: fakeroot debian/rules clean fakeroot debian/rules updateconfigs fakeroot debian/rules binary-headers binary-generic binary-perarch (or binary-lowlatency for lowlatency builds) I'm not using cloud-tools packages. Anyways I guess you can close this and it can be reopened if I have time to attempt to reproduce the bug. it's not a critical patch but it's queued for 0.6.5-release upstream so there's probably no harm including it in ubuntu kernel. Thanks -- 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/1587686 Title: ZFS: Running ztest repeatedly for long periods of time eventually results in "zdb: can't open 'ztest': No such file or directory" Status in Native ZFS for Linux: New Status in linux package in Ubuntu: Incomplete Status in zfs-linux package in Ubuntu: In Progress Bug description: Problem: Running ztest repeatedly for long periods of time eventually results in "zdb: can't open 'ztest': No such file or directory" This bug affects the xenial kernel built-in ZFS as well as the package zfs-dkms. I don't believe ZFS 0.6.3-stable or 0.6.4-release are effected, 0.6.5-release seems to have included the offending commit. Sorry for excessive "Affects" tagging, I'm still new to this and unsure of the proper packages to report this against and/or how to properly add the upstream issues/commits. Upstream bug report: https://github.com/zfsonlinux/zfs/issues/4129 "ztest can occasionally fail because zdb cannot locate the pool after several hours of run time. This appears to be caused be an empty cache file." How to reproduce: run ztest repeatedly such as a command like this and it will eventually fail: ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* && sleep 3 && ztest -T 3600 && rm /tmp/z* (I have /tmp mounted on tmpfs with a 10G limit but I don't believe this is related in any way, and I've confirmed it's not running out of space) Upstream fix: https://github.com/zfsonlinux/zfs/commit/151f84e2c32f690b92c424d8c55d2dfccaa76e51 Description: Fix ztest truncated cache file "Commit efc412b updated spa_config_write() for Linux 4.2 kernels to truncate and overwrite rather than rename the cache file. This is the correct fix but it should have only been applied for the kernel build. In user space rename(2) is needed because ztest depends on the cache file." Associated pull request for above commit: https://github.com/zfsonlinux/zfs/pull/4130 I'm not sure why this wasn't backported to release but it's in zfs master. I've Reproduced this bug on xenial kernels 4.4.0-22-generic, 4.4.0-23-generic, 4.4.0-22-lowlatency, and 4.4.0-23-lowlatency as well as various xenial master-next builds. After applying the above commit patch to kernel and building/installing kernel manually, ztest runs fine. I've also separately tested the commit patch on zfs-dkms package which also appears to fix the issue. Note however, there may still be some other outstanding ztest related issues upstream - especially when preempt and hires timers are used. I'm currently testing more heavily against lowlatency builds and master-next. (I'm unsure how to associate this bug with multiple packages but zfs- dkms and linux-image-* packages both are affected). P.S. Also of note is https://github.com/zfsonlinux/zfs/commit/60a4ea3f948f1596b92b666fc7dd21202544edbb "Fix inverted logic on none elevator comparison" - which interestingly was signed-off-by canonical but curiously not included in the xenial kernel or zfs-dkms packages. It was however, backported to 0.6.5-release upstream. To manage notifications about this bug go to: https://bugs.launchpad.net/zfs/+bug/1587686/+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
