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Searching in: Trouble Reports
ID: TR12N07418
Added on: 2016-12-14
Last update: 2017-02-01
Solved in version: 5.2.11
Platform: All Linux Platforms
Product: NoMachine Server
Severity: Minor
Status: Closed
Display server could terminate unexpectedly when the available shared memory on the system is exhausted
This issue can occur when exhausting the available shared memory on the system and it is accompanied by the following lines in the 'session' log of the display server process:
nxagentSharedMemoryInit: WARNING! Failed to allocate shared memory segment of 33554432 bytes.
nxagentSharedMemoryInit: WARNING! Trying to allocate 16777216 bytes.
This edge case is not handled properly and a segfault occurs with the following backtace:
#0  __memset_sse2 () at ../sysdeps/x86_64/multiarch/../memset.S:80
#1  0x00007fbf04ad949f in ?? () from /usr/NX/lib/
#2  0x00007fbf04ae473d in nxagentDisplayServerInit () from /usr/NX/lib/
#3  0x00007fbf04ae5145 in nxagentShadowInit () from /usr/NX/lib/
#4  0x00007fbf04ac44fb in nxagentShadowClientCallback () from /usr/NX/lib/
#5  0x00007fbf0240b2dc in _CallCallbacks () from /usr/NX/lib/
#6  0x00007fbf02405f00 in NextAvailableClient () from /usr/NX/lib/
#7  0x00007fbf024724bb in ?? () from /usr/NX/lib/
#8  0x00007fbf02473b05 in EstablishNewConnections () from /usr/NX/lib/
#9  0x00007fbf0240add1 in ProcessWorkQueue () from /usr/NX/lib/
#10 0x00007fbf0246d69e in WaitForSomething () from /usr/NX/lib/
#11 0x00007fbf02406397 in Dispatch () from /usr/NX/lib/
#12 0x00007fbf023f392e in _NXDisplayMain () from /usr/NX/lib/

It has to be noted that this bug is not the reason for the exhausted shared memory, and, if some shared memory is not freed to make room for new allocations, it could be impossible to start new sessions.