I've just upgraded to 4.15.0.29.31 from proposed, and I can confirm Alan
Jenkins' comment #17: the bug is still present:
$ uname -r
4.15.0-29-generic
$ sudo ./check block/016
block/016 (send a signal to a process waiting on a frozen queue) [failed]
runtime ... 8,390s
--- tests/block/016.out 2018-07-18 10:04:54.136492698 -0300
+++ results/nodev/block/016.out.bad 2018-07-18 10:22:55.171574748 -0300
@@ -1,2 +1,3 @@
Running block/016
+dd: error reading '/dev/nullb0': Input/output error
Test complete
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https://bugs.launchpad.net/bugs/1776887
Title:
Critical upstream bugfix missing in Ubuntu 18.04 - frequent Xorg crash
after suspend
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Bionic:
Fix Committed
Bug description:
== SRU Justification ==
This upstream bug has been confirmed to affect Ubuntu users[1]. As
per the fix commit (below), the most frequent symptom is a crash of
Xorg/Xwayland, i.e. killing the entire GUI, when a laptop is woken
from system sleep. Frequency of the bug is described as once every
few days[2].
[1] E.g. this user confirms the bug & very specific workaround:
https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1760450/comments/11
[2] E.g. this log of crashes:
https://bugzilla.redhat.com/show_bug.cgi?id=1553979#c23
This is a bug in blk-core.c. It is not specific to any one hardware
driver. Technically the suspend bug is triggered by the SCSI core -
which is used by *all SATA devices*.
The commit also includes a test which quickly and reliably proves the
existence of a horrifying bug.
I guess you might avoid this bug only if you have root on NVMe. The
other way to not hit the Xorg crash is if you don't use all your RAM,
so there's no pressure that leads to cold pages of Xorg being swapped.
Also, you won't reproduce the Xorg crash if you suspend+resume
immediately. (This frustrated my tests at one point, it only
triggered after left the system suspended over lunch :).
Fix: "block: do not use interruptible wait anywhere"
in kernel 4.17:
https://github.com/torvalds/linux/commit/1dc3039bc87ae7d19a990c3ee71cfd8a9068f428
in kernel 4.16.8:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-
stable.git/commit/?h=linux-4.16.y&id=7859056bc73dea2c3714b00c83b253d4c22bf7b6
lack of fix in 4.15.0-24.26 (ubuntu 18.04): https://git.launchpad.net
/~ubuntu-kernel/ubuntu/+source/linux/+git/bionic/tree/block/blk-
core.c?id=Ubuntu-4.15.0-24.26#n856
I.e., this bug is still present in Ubuntu source package
linux-4.15.0-24.26 (and 4.15.0-23.25). I attach hardware details
(lspci-vnvn.log) of a system where this bug is known to happen.
Regards
Alan
WORKAROUND: Use kernel parameter:
scsi_mod.scan=sync
== Fix ==
1dc3039bc87a ("block: do not use interruptible wait anywhere")
== Regression Potential ==
Low. This patch has been sent to stable, so it has had additional
upstream review.
== Test Case ==
A test kernel was built with this patch and tested by the original bug
reporter.
The bug reporter states the test kernel resolved the bug.
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