This bug was fixed in the package linux - 4.4.0-17.33
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linux (4.4.0-17.33) xenial; urgency=low
[ Tim Gardner ]
* Release Tracking Bug
- LP: #1563441
* ISST-LTE: pVM:high cpus number need a high crashkernel value in kdump
(LP: #1560552)
- SAUCE: (noup) ppc64
8d91f8b15361dfb438ab6eb3b319e2ded43458ff ('printk: do cond_resched()
between lines while outputting to consoles') came in via 4.4 stable. I
also cherry-picked 6b97a20d3a7909daa06625d4440c2c52d7bf08d7 ('printk:
set may_schedule for some of console_trylock() callers')
** Also affects: linux (Ubuntu
this is (mostly) fixed in 2 commits, from the original bug (bug 1505564)
kernel level commit 5a3a466ae3c86ad6b8fc36c2efc5f541ef0ed89e (from
git://kernel.ubuntu.com/ubuntu/ubuntu-trusty.git lts-backport-vivid)
partially fixes this problem, by using the console_may_schedule var
correctly. The
This isn't actually an issue with the serial port driver, it's the
printk code that is failing to schedule while printing out all the msgs.
During printk(), if the console lock is held, the msgs are queued up,
and inside console_unlock() any queued msgs are sent to the console
before unlocking:
** Summary changed:
- serial port driver under heavy load can hang system
+ lots of printk to serial console can hang system for long time
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https://bugs.launchpad.net/bugs/1534216
