The fix in question is:
commit e7a2fa70c3b0d8c8cee2b484038bb5623c7c1ea9
Author: Tom Caputi <tcap...@datto.com>
Date: Tue Aug 27 12:55:51 2019 -0400
Fix deadlock in 'zfs rollback'
Currently, the 'zfs rollback' code can end up deadlocked due to
the way the kernel handles unreferenced inodes on a suspended fs.
Essentially, the zfs_resume_fs() code path may cause zfs to spawn
new threads as it reinstantiates the suspended fs's zil. When a
new thread is spawned, the kernel may attempt to free memory for
that thread by freeing some unreferenced inodes. If it happens to
select inodes that are a a part of the suspended fs a deadlock
will occur because freeing inodes requires holding the fs's
z_teardown_inactive_lock which is still held from the suspend.
This patch corrects this issue by adding an additional reference
to all inodes that are still present when a suspend is initiated.
This prevents them from being freed by the kernel for any reason.
Reviewed-by: Alek Pinchuk <apinc...@datto.com>
Reviewed-by: Brian Behlendorf <behlendo...@llnl.gov>
Signed-off-by: Tom Caputi <tcap...@datto.com>
Closes #9203
** Changed in: zfs-linux (Ubuntu)
Assignee: (unassigned) => Colin Ian King (colin-king)
** Changed in: zfs-linux (Ubuntu)
Importance: Undecided => High
** Changed in: zfs-linux (Ubuntu)
Status: New => In Progress
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https://bugs.launchpad.net/bugs/1847832
Title:
Backport ZoL pull request 9203 into the official packages.
Status in zfs-linux package in Ubuntu:
In Progress
Bug description:
Hopefully this is the correct bug tracker to report this on.
Recently, I ran into a bug in ZFS as shipped in Ubuntu 19.10 that
caused the kernel to deadlock and the system to eventually hang.
I was advised by a ZFS on Linux project maintainer that this was a bug
that was fixed in 0.8.2.
The relevant pull request is here:
https://github.com/zfsonlinux/zfs/pull/9203
It would probably be a good idea to backport that pull request into
19.10's build of ZFS.
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