Andreas Kling 3012b224f0 Kernel: Fix intermittent assertion failure in sys$exec() ...

While setting up the main thread stack for a new process, we'd incur
some zero-fill page faults. This was to be expected, since we allocate
a huge stack but lazily populate it with physical pages.

The problem is that page fault handlers may enable interrupts in order
to grab a VMObject lock (or to page in from an inode.)

During exec(), a process is reorganizing itself and will be in a very
unrunnable state if the scheduler should interrupt it and then later
ask it to run again. Which is exactly what happens if the process gets
pre-empted while the new stack's zero-fill page fault grabs the lock.

This patch fixes the issue by creating new main thread stacks before
disabling interrupts and going into the critical part of exec().

2019-12-18 23:03:23 +01:00

23 KiB

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