This bug was fixed in the package zfs-linux - 0.6.5.6-0ubuntu28
---
zfs-linux (0.6.5.6-0ubuntu28) xenial; urgency=medium
* Fix ZFS shrinker deadlock with xattrs (LP: #1839521)
- Upstream ZFS fix 31b6111fd92a ("Kill zp->z_xattr_parent to prevent
pinning")
and ddae16a9cf0b
Verification done for linux on xenial-proposed.
The inodes for file, xattr dir, and xattr child are all evicted at file
removal time, not making it to any disposal list after file removal.
So the window/scenario for the problem to occur is not present anymore.
Log
---
$ uname -rv
4.4.0-160-gene
Hi @mathew-hodson,
This fix is needed in the Linux kernel package for Xenial as well (it
duplicates the zfs-linux/dkms source).
Shouldn't the 'linux' source package still be tracked?
Thanks,
Mauricio
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** No longer affects: linux (Ubuntu)
** No longer affects: linux (Ubuntu Xenial)
** No longer affects: linux (Ubuntu Bionic)
** No longer affects: linux (Ubuntu Disco)
** No longer affects: linux (Ubuntu Eoan)
** No longer affects: zfs-linux (Ubuntu Bionic)
** No longer affects: zfs-linux (Ub
Verification done for zfs-linux on xenial-proposed.
The inodes for file, xattr dir, and xattr child are all evicted at file
removal time, not making it to any disposal list after file removal.
So the window/scenario for the problem to occur is not present anymore.
Log
---
$ echo 'deb http://arc
Hello Mauricio, or anyone else affected,
Accepted zfs-linux into xenial-proposed. The package will build now and
be available at https://launchpad.net/ubuntu/+source/zfs-
linux/0.6.5.6-0ubuntu28 in a few hours, and then in the -proposed
repository.
Please help us by testing this new package. See
** Changed in: linux (Ubuntu Xenial)
Status: In Progress => Fix Committed
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https://bugs.launchpad.net/bugs/1839521
Title:
Xenial: ZFS deadlock in shrinker path with xattrs
To ma
Colin, thanks for sponsoring and additional testing!
Is this ZFS regression test suite available to other people?
It sounds great for future work with ZFS.
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Thanks Mauricio, I've sponsored this package, and sent the kernel
related changes to the kernel-team mailing list:
https://lists.ubuntu.com/archives/kernel-team/2019-August/102938.html
I also sanity checked the code with the ubuntu kernel team ZFS
regression tests and they all pass successfully.
** Description changed:
[Impact]
- * Xenial's ZFS can deadlock in the memory shrinker path
-after removing files with extended attributes (xattr).
+ * Xenial's ZFS can deadlock in the memory shrinker path
+ after removing files with extended attributes (xattr).
- * Extended attri
Fix Change Details
--
(Compare with comment #3)
The xattr dir/child inodes are evicted/disposed
immediately on file removal, not on shrinker.
$ touch /zfs/file
<...>-23940 [006] d... 10808.746798: p_zfs_mknode_0:
(zfs_mknode+0x0/0xe00 [zfs]) flag=0x0 dzp=0x88011a
debdiff for zfs-linux (zfs-linux_shrinker-deadlock-xattr.debdiff)
based on ubuntu/xenial-devel branch from LP source pkg git repo [1].
[1] https://git.launchpad.net/ubuntu/+source/zfs-linux
** Patch added: "zfs-linux_shrinker-deadlock-xattr.debdiff"
https://bugs.launchpad.net/ubuntu/+source/z
zfs-test results w/ original & modified zfs-dkms
original
$ uname -rv
4.4.0-159-generic #187-Ubuntu SMP Thu Aug 1 16:28:06 UTC 2019
$ modinfo zfs | head
filename: /lib/modules/4.4.0-159-generic/updates/dkms/zfs.ko
version:0.
[Original Description]
One LXC user reported lots of processes stuck in D state:
several threads waiting in the memory shrinker semaphore
(this symptom was thought to be/fixed via LP bug 1817628).
After some time, a provided crashdump revealed the issue
in ZFS's evict node path running in memory
Problem Details:
---
Helper scripts
(create /zfs.img and mount it on /zfs; and setup kprobe events for debug)
$ sudo ./zfs-mount.sh
$ sudo ./zfs-kprobes.sh
Print kprobe events to screen as we go:
$ sudo cat /sys/kernel/debug/tracing/trace_pipe &
Create file:
- allocates normal/fil
** Attachment added: "zfs-mount.sh"
https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1839521/+attachment/5281632/+files/zfs-mount.sh
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T
** Attachment added: "zfs-kprobes.sh"
https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1839521/+attachment/5281633/+files/zfs-kprobes.sh
** Attachment removed: "kmod-zget.c"
https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1839521/+attachment/5281631/+files/kmod-zget.c
--
zfs-test test suite on xenial
-
Build/install the latest zfs-test suite from zfs.git:
$ git clone https://github.com/zfsonlinux/zfs.git
$ cd zfs
$ git log --oneline -1
c81f179 Metaslab max_size should be persisted while unloaded
$ sudo apt-get build-dep zfs-linux
$ su
Fix Details
---
Problem report (GH Issue) upstream in ZFS on Linux:
https://github.com/zfsonlinux/zfs/issues/4816 ("Looping in zfs_zget()")
With very similar stack trace (syscall -> shrink ->
zfs_{inactive/rmnode/purgedir/zget})
https://github.com/zfsonlinux/zfs/issues/48
Problem Summary:
---
If an xattr directory inode and its xattr child inode are on the _same_
disposal list,
and the xattr directory inode is _before_ its xattr child inode in this
disposal list...
Then zfs_purgedir() of the xattr directory calls zfs_zget() for the xattr child
inode
** Attachment added: "kmod-zget.c"
https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1839521/+attachment/5281634/+files/kmod-zget.c
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Tit
Test-case for the problem (kmod-zget.c).
Header comments with steps to reproduce.
** Attachment added: "kmod-zget.c"
https://bugs.launchpad.net/ubuntu/+source/zfs-linux/+bug/1839521/+attachment/5281631/+files/kmod-zget.c
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