virtiofs: enable test case for mapping virtiofs MAP_PRIVATE#13964
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virtiofs: enable test case for mapping virtiofs MAP_PRIVATE#13964
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benhillis
requested review from
Brian-Perkins,
OneBlue,
Copilot,
craigloewen-msft and
justus-camp-microsoft
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Pull request overview
This PR enables the virtiofs test variation for mapping app execution links with MAP_PRIVATE and clarifies the specific limitation preventing MAP_SHARED support on virtiofs.
Key changes:
- Adds a new MAP_PRIVATE mmap test that runs unconditionally for all filesystem types, verifying that app execution links can be mapped with MAP_PRIVATE
- Updates the virtiofs-specific comment to clarify that the limitation is specifically about MAP_SHARED support, not a general debugging issue
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| LxtCheckMapErrno(Mapping = mmap(NULL, 2, PROT_READ, MAP_PRIVATE, Fd, 0)); | ||
| LxtCheckMemoryEqual(Mapping, "MZ", 2); | ||
| LxtCheckResult(munmap(Mapping, 2)); |
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After successfully unmapping the MAP_PRIVATE mapping, the Mapping variable should be set to MAP_FAILED. Without this, when running on virtiofs, the ErrorExit cleanup code at line 3493-3495 will attempt to munmap an already-unmapped address, which can cause undefined behavior. Add Mapping = MAP_FAILED; after this line to prevent double-free of the mapping.
Suggested change
| LxtCheckResult(munmap(Mapping, 2)); | |
| LxtCheckResult(munmap(Mapping, 2)); | |
| Mapping = MAP_FAILED; |
OneBlue
approved these changes
Dec 23, 2025
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This test enables the virtiofs variation for mapping an app execution link as MAP_PRIVATE and clarifies what support is missing.