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Kernel: Fix partial munmap() deallocating still-in-use VM

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We were always returning the full VM range of the partially-unmapped
Region to the range allocator. This caused us to re-use those addresses
for subsequent VM allocations.

This patch also skips creating a new VMObject in partial munmap().
Instead we just make split regions that point into the same VMObject.

This fixes the mysterious GCC ICE on large C++ programs.
This commit is contained in:
Andreas Kling 2019-09-27 20:17:41 +02:00
parent d5f3972012
commit 2584636d19
4 changed files with 17 additions and 12 deletions
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5
Kernel/VM/MemoryManager.cpp
View file

@ -705,7 +705,7 @@ void MemoryManager::map_region_at_address(PageDirectory& page_directory, Region&
}
}
bool MemoryManager::unmap_region(Region& region)
bool MemoryManager::unmap_region(Region& region, bool deallocate_range)
{
ASSERT(region.page_directory());
InterruptDisabler disabler;
@ -722,7 +722,8 @@ bool MemoryManager::unmap_region(Region& region)
dbgprintf("MM: >> Unmapped V%p => P%p <<\n", vaddr, physical_page ? physical_page->paddr().get() : 0);
#endif
}
region.page_directory()->range_allocator().deallocate({ region.vaddr(), region.size() });
if (deallocate_range)
region.page_directory()->range_allocator().deallocate(region.range());
region.release_page_directory();
return true;
}