[release/10.0] Limit doublemapper maximum size #119392
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The double mapping currently sets the maximum size of the double mapped memory to 2TB. However, that causes the runtime to fail to start if there is a rlimit for max file size set to a smaller value. This change fixed the problem by clipping the max double mapped memory size by that rlimit and also uses much more conservative size even without the file size limit set. It is now set to the total amount of physical memory by default and also clipped by the virtual memory rlimit. Close #117819
Even on 32 bit targets, more than 4GB memory may be available.
jkotas
approved these changes
Sep 5, 2025
jeffschwMSFT
approved these changes
Sep 5, 2025
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Backport of #119316 to release/10.0
/cc @janvorli
Customer Impact
When a customer sets maximum file size limit on Linux using the
ulimit -f XXXXcommand to a value smaller than 2TB (4GB on 32 bit OS), .NET process fails to start and crashes with SIGXFSZ signal due to the executable allocator in .NET setting maximum size of shared memory for double mapping to 2TB (4GB on 32 bit OS). See issue #117819.Regression
Testing
Local testing app running under a debugger with
ulimit -fset to low valuesRisk
Low, the change causes the maximum size of executable code to be limited by the: