Bug#934752: libc6: SEGFAULTs caused by tcache after upgrade to Buster
Sorry for late answer.
On 17. 08. 19 22:18, Florian Weimer wrote:
* Pavel Matěja:
The strange means they appear only on 2 servers out of 6.
Servers with Xeon E5606 and Pentium G6950 were running fine while Xeon
E3-1220 v6 produced crashes.
It did not matter if the host Debian was Stretch or Buster.
Do you see crashes on stretch as well? What does the backtrace look
like there?
I newer saw the SEGFAULT when we had Stretch based chroot.
I had just one SEGFAULT on Stretch host but I didn't collect coredumps
back then.
Unfortunately the server is already running Buster.
Since the bug is caused by new libc in chroot I should be able to
install just kernel from Stretch and wait for the SEGFAULT, right?
I think the backtrace will be the same anyway.
SSLv3 and TLS code path looked quite distinct to cause the same problem.
Based on info that SEGFAULTs are related to memory allocation in new
libc and CPU performance I found
http://51.15.138.76/patch/17499/
where Wilco Dijkstra discuss some problems with tcache which "leads to
various crashes in benchtests"
I was under the impression that this problem only occurs if one of the
tunables has an out-of-bounds value. Do you set any tunables?
No, I didn't even know they existed.
I did not read the libc sources yet so I don't know what does the patch
actually fixes neither if it helps with my problem.
Pavel Matěja
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