[lttng-dev] [RELEASE] LTTng-modules 2.9.11, 2.10.8, 2.11.0-rc2 (Linux kernel tracer)

[Mathieu Desnoyers]

Hi,

This is a set of bugfix releases of the LTTng modules kernel tracer.
It covers the three currently active lttng-modules branches: the
2.9 and 2.10 stable branches, as well as the 2.11 branch in release
candidate cycle.

Those releases add support for kernel 4.19.

One important improvement is to prevent allocation of buffers larger
than the available memory, which can cause the OOM killer to trigger.
Even if the OOM killer end up having to trigger, the current OOM kill
target is set to the current thread while allocating buffers.

Enjoy!

Mathieu

Project website: http://lttng.org
Documentation: http://lttng.org/docs
Download link: http://lttng.org/download

Changelog:

2018-11-01 (National Men Make Dinner Day) LTTng modules 2.11.0-rc2
* Fix: update kvm instrumentation for SLES12 SP2 LTSS >= 4.4.121-92.92
* Fix: Add missing const to lttng_tracepoint_ptr_deref prototype
* Fix: adapt to kernel relative references
* Fix: implicit declarations caused by buffer size checks.
* Prevent allocation of buffers if exceeding available memory
* Fix: btrfs instrumentation namespacing
* Fix: Convert rcu tracepointis to gp_seq (v4.19)
* Fix: tracing: Centralize preemptirq tracepoints (4.19)
* Fix: net: expose sk wmem in sock_exceed_buf_limit tracepoint (4.19)
* Fix: access migrate_disable field directly
* Fix: out of memory error handling

2018-11-01 (National Men Make Dinner Day) LTTng modules 2.10.8
* Fix: update kvm instrumentation for SLES12 SP2 LTSS >= 4.4.121-92.92
* Fix: Add missing const to lttng_tracepoint_ptr_deref prototype
* Fix: adapt to kernel relative references
* Fix: implicit declarations caused by buffer size checks.
* Prevent allocation of buffers if exceeding available memory
* Fix: Convert rcu tracepointis to gp_seq (v4.19)
* Fix: net: expose sk wmem in sock_exceed_buf_limit tracepoint (4.19)
* Fix: access migrate_disable field directly
* Fix: out of memory error handling

2018-11-01 (National Men Make Dinner Day) LTTng modules 2.9.11
* Fix: update kvm instrumentation for SLES12 SP2 LTSS >= 4.4.121-92.92
* Fix: Add missing const to lttng_tracepoint_ptr_deref prototype
* Fix: adapt to kernel relative references
* Fix: implicit declarations caused by buffer size checks.
* Prevent allocation of buffers if exceeding available memory
* Fix: Convert rcu tracepointis to gp_seq (v4.19)
* Fix: net: expose sk wmem in sock_exceed_buf_limit tracepoint (4.19)
* Fix: access migrate_disable field directly
* Fix: out of memory error handling

[Joel Fernandes via lttng-dev]

On Thu, Nov 1, 2018 at 3:56 PM Mathieu Desnoyers

Post by Mathieu Desnoyers
Hi,
This is a set of bugfix releases of the LTTng modules kernel tracer.
It covers the three currently active lttng-modules branches: the
2.9 and 2.10 stable branches, as well as the 2.11 branch in release
candidate cycle.
Those releases add support for kernel 4.19.
One important improvement is to prevent allocation of buffers larger
than the available memory, which can cause the OOM killer to trigger.
Even if the OOM killer end up having to trigger, the current OOM kill
target is set to the current thread while allocating buffers.

This is interesting. Me and Steve were looking at exactly this issue
with the ftrace ring buffer a few months ago. Turns out that even
setting the OOM kill target may not be enough to prevent all OOMs. I
don't remember the reason why not, I'll have to dig out those threads
but that's what the -mm folks said at the time. I did remember vaguely
that I tested it and the kill target doesn't always get killed.. its
possible that something *other* parallel allocation can be victimized
AFAIR, even though the culprit is the kill target.

- Joel