WindowsMappings::Collect resets each part of the range as it walks it:
it marks shared views seen and resets private pages' write-watch bits.
When it then met a NOACCESS view or memory that is not committed
private memory, it returned false with the earlier parts already reset,
so their writes were lost to the caller's fallback. With reset, the
whole range is now checked first and nothing is reset when it fails.
AI-assisted (Claude Code).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Write tracking protects shared guest pages read-only. A push on a fiber
stack in such a page faults, and Windows cannot dispatch it because the
exception frame lands on the same protected stack, so the process was
terminated without a report. Pin fiber contexts writable for their
lifetime; pinned pages are always collected as written.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A file read into guest memory is a host write: before the I/O it pins the shared pages it
covers, which reopens any page armed for write tracking and keeps write tracking from arming
it again until the read ends, when the pages count as written. A destination the guest cannot
write fails with EFAULT before any I/O; read and pread throw as for any failed read, AIO
reports SCE_KERNEL_ERROR_EFAULT, and APR throws. APR also throws when a read ends before the
requested size.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
MapViewOfFile3 takes an offset that is a multiple of the allocation granularity
(64 KiB), while shared guest pages are 16 KiB. An alias of a range starting at
a 16 KiB page that is not 64 KiB aligned was refused ("the section offset is not
a multiple of the allocation granularity"), so its host import failed. The view
now starts at the granularity boundary below the offset, the alias points past
the lead, and unmapping rounds back to the view's base.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Scott Schuster
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