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Bug #3971

Updated by pespin 3 months ago

Initially found and described in detail here: https://osmocom.org/issues/3339?#note-15

My system totally freezes for 2-5 seconds before/during the time osmo-trx starts failing reading/writing on OS#3339. That happens about 30 second after starting osmo-trx-lms. My XServer blocks and music playing from a youtube video on the background also either stops or plays in a 1 sec loop. When I recover control of my system, I can see in the logs of osmo-trx the read/write failure from OS#3339.

Through htop one can easily see that upon starting osmo-trx-lms, memory suddenly grows until filling my 16GB, and then is when my system freezes and osmo-trx starts failing, during that time kernel is working heavily to free up memory.

Interestingly, if I strace the osmo-trx-lms I don't see this kind of issue, but it's true too that the CPU consumption drops a lot too. strace only shows heavy use of calls: accept(), poll() and select().

If I ctrl+z (SIGSTOP) the osmo-trx-lms, the kernel stops acquiring memory (and releases most of it). Once I use "fg" to SIGCONTINUE the process, it continues acquiring memory like crazy. Same if I use gdb to do the same kind of operation.

Allocation happens in kernel memory, not process-related memory:
<pre>
kernel dynamic memory 10.2G 1009.3M 9.2G <-----!!!!!!!

OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
26117200 26114592 99% 0.25K 816487 32 6531896K filp <---!!!!!!!
26120640 26118794 99% 0.06K 408135 64 1632540K kmalloc-64 <---!!!!!!!
</pre>

* Reproducible both on LimeSDR-USB and LimeSDR-mini HW.
* reproducible both on USB2 and USB3.
* Reproducible both on LimeSuite 18.10.* and 19.01.*
* Reproducible both on kernel 4.19.4-arch1-1-ARCH and 5.0.9-arch1-1-ARCH
* Reproducible on 1.0.22-1
* Reproducible both with ASan enabled or disabled.


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