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MemoryManager: Off-by-one error when collecting memory pages.

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Notice that we ensured that the size is a multiple of the page size and
that there is at least one page there, otherwise, this change would be
invalid.

We create an empty region and then expand it:

    // First iteration.
    m_user_physical_regions.append(PhysicalRegion::create(addr, addr));

    // Following iterations.
    region->expand(region->lower(), addr);

So if the memory region only has one page, we would end up with an empty
region. Thus we need to do one more iteration.
This commit is contained in:
asynts 2020-10-10 18:05:22 +02:00 committed by Andreas Kling
parent f68ed6d25b
commit 71fd54f76b
Notes: sideshowbarker 2024-07-19 01:56:04 +09:00 
Author: https://github.com/asynts
Commit: https://github.com/SerenityOS/serenity/commit/71fd54f76b6
Pull-request: https://github.com/SerenityOS/serenity/pull/3742
1 changed files with 1 additions and 1 deletions
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2
Kernel/VM/MemoryManager.cpp
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@ -151,7 +151,7 @@ void MemoryManager::parse_memory_map()
klog() << "MM: considering memory at " << String::format("%p", (FlatPtr)mmap->addr) << " - " << String::format("%p", (FlatPtr)(mmap->addr + mmap->len));
#endif
for (size_t page_base = mmap->addr; page_base < (mmap->addr + mmap->len); page_base += PAGE_SIZE) {
for (size_t page_base = mmap->addr; page_base <= (mmap->addr + mmap->len); page_base += PAGE_SIZE) {
auto addr = PhysicalAddress(page_base);
if (addr.get() < used_range_end.get() && addr.get() >= used_range_start.get())