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https://github.com/RGBCube/serenity
synced 2025-07-24 21:37:34 +00:00
Kernel: Clean up a bunch of wrong-looking Region/VMObject code
Since a Region is merely a "window" onto a VMObject, it can both begin and end at a distance from the VMObject's boundaries. Therefore, we should always be computing indices into a VMObject's physical page array by adding the Region's "first_page_index()". There was a whole bunch of code that forgot to do that. This fixes many wrong behaviors for Regions that start part-way into a VMObject.
This commit is contained in:
parent
fe455c5ac4
commit
a221cddeec
2 changed files with 25 additions and 23 deletions
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@ -291,14 +291,15 @@ const Region* MemoryManager::region_from_vaddr(const Process& process, VirtualAd
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bool MemoryManager::zero_page(Region& region, unsigned page_index_in_region)
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bool MemoryManager::zero_page(Region& region, unsigned page_index_in_region)
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{
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{
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ASSERT_INTERRUPTS_DISABLED();
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ASSERT_INTERRUPTS_DISABLED();
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auto& vmo = region.vmobject();
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ASSERT(region.vmobject().is_anonymous());
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auto& vmo_page = vmo.physical_pages()[region.first_page_index() + page_index_in_region];
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ASSERT(vmo.is_anonymous());
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auto& vmobject = region.vmobject();
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auto& vmobject_physical_page_entry = vmobject.physical_pages()[region.first_page_index() + page_index_in_region];
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// NOTE: We don't need to acquire the VMObject's lock.
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// NOTE: We don't need to acquire the VMObject's lock.
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// This function is already exclusive due to interrupts being blocked.
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// This function is already exclusive due to interrupts being blocked.
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if (!vmo_page.is_null()) {
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if (!vmobject_physical_page_entry.is_null()) {
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#ifdef PAGE_FAULT_DEBUG
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#ifdef PAGE_FAULT_DEBUG
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dbgprintf("MM: zero_page() but page already present. Fine with me!\n");
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dbgprintf("MM: zero_page() but page already present. Fine with me!\n");
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#endif
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#endif
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@ -313,7 +314,7 @@ bool MemoryManager::zero_page(Region& region, unsigned page_index_in_region)
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#ifdef PAGE_FAULT_DEBUG
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#ifdef PAGE_FAULT_DEBUG
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dbgprintf(" >> ZERO P%p\n", physical_page->paddr().get());
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dbgprintf(" >> ZERO P%p\n", physical_page->paddr().get());
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#endif
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#endif
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vmo.physical_pages()[page_index_in_region] = move(physical_page);
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vmobject_physical_page_entry = move(physical_page);
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region.remap_page(page_index_in_region);
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region.remap_page(page_index_in_region);
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return true;
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return true;
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}
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}
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@ -321,8 +322,9 @@ bool MemoryManager::zero_page(Region& region, unsigned page_index_in_region)
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bool MemoryManager::copy_on_write(Region& region, unsigned page_index_in_region)
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bool MemoryManager::copy_on_write(Region& region, unsigned page_index_in_region)
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{
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{
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ASSERT_INTERRUPTS_DISABLED();
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ASSERT_INTERRUPTS_DISABLED();
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auto& vmo = region.vmobject();
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auto& vmobject = region.vmobject();
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if (vmo.physical_pages()[page_index_in_region]->ref_count() == 1) {
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auto& vmobject_physical_page_entry = vmobject.physical_pages()[region.first_page_index() + page_index_in_region];
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if (vmobject_physical_page_entry->ref_count() == 1) {
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#ifdef PAGE_FAULT_DEBUG
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#ifdef PAGE_FAULT_DEBUG
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dbgprintf(" >> It's a COW page but nobody is sharing it anymore. Remap r/w\n");
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dbgprintf(" >> It's a COW page but nobody is sharing it anymore. Remap r/w\n");
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#endif
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#endif
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@ -337,7 +339,7 @@ bool MemoryManager::copy_on_write(Region& region, unsigned page_index_in_region)
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#ifdef PAGE_FAULT_DEBUG
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#ifdef PAGE_FAULT_DEBUG
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dbgprintf(" >> It's a COW page and it's time to COW!\n");
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dbgprintf(" >> It's a COW page and it's time to COW!\n");
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#endif
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#endif
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auto physical_page_to_copy = move(vmo.physical_pages()[page_index_in_region]);
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auto physical_page_to_copy = move(vmobject_physical_page_entry);
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auto physical_page = allocate_user_physical_page(ShouldZeroFill::No);
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auto physical_page = allocate_user_physical_page(ShouldZeroFill::No);
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u8* dest_ptr = quickmap_page(*physical_page);
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u8* dest_ptr = quickmap_page(*physical_page);
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const u8* src_ptr = region.vaddr().offset(page_index_in_region * PAGE_SIZE).as_ptr();
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const u8* src_ptr = region.vaddr().offset(page_index_in_region * PAGE_SIZE).as_ptr();
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@ -345,7 +347,7 @@ bool MemoryManager::copy_on_write(Region& region, unsigned page_index_in_region)
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dbgprintf(" >> COW P%p <- P%p\n", physical_page->paddr().get(), physical_page_to_copy->paddr().get());
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dbgprintf(" >> COW P%p <- P%p\n", physical_page->paddr().get(), physical_page_to_copy->paddr().get());
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#endif
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#endif
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memcpy(dest_ptr, src_ptr, PAGE_SIZE);
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memcpy(dest_ptr, src_ptr, PAGE_SIZE);
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vmo.physical_pages()[page_index_in_region] = move(physical_page);
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vmobject_physical_page_entry = move(physical_page);
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unquickmap_page();
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unquickmap_page();
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region.set_should_cow(page_index_in_region, false);
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region.set_should_cow(page_index_in_region, false);
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region.remap_page(page_index_in_region);
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region.remap_page(page_index_in_region);
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@ -355,24 +357,23 @@ bool MemoryManager::copy_on_write(Region& region, unsigned page_index_in_region)
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bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_region)
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bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_region)
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{
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{
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ASSERT(region.page_directory());
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ASSERT(region.page_directory());
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auto& vmo = region.vmobject();
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ASSERT(region.vmobject().is_inode());
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ASSERT(vmo.is_inode());
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auto& inode_vmobject = static_cast<InodeVMObject&>(vmo);
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auto& vmobject = region.vmobject();
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auto& inode_vmobject = static_cast<InodeVMObject&>(vmobject);
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auto& vmo_page = inode_vmobject.physical_pages()[region.first_page_index() + page_index_in_region];
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auto& vmobject_physical_page_entry = inode_vmobject.physical_pages()[region.first_page_index() + page_index_in_region];
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InterruptFlagSaver saver;
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InterruptFlagSaver saver;
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sti();
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sti();
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LOCKER(vmo.m_paging_lock);
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LOCKER(vmobject.m_paging_lock);
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cli();
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cli();
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if (!vmo_page.is_null()) {
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if (!vmobject_physical_page_entry.is_null()) {
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#ifdef PAGE_FAULT_DEBUG
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#ifdef PAGE_FAULT_DEBUG
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dbgprintf("MM: page_in_from_inode() but page already present. Fine with me!\n");
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dbgprintf("MM: page_in_from_inode() but page already present. Fine with me!\n");
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#endif
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#endif
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region.remap_page( page_index_in_region);
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region.remap_page(page_index_in_region);
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return true;
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return true;
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}
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}
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@ -395,8 +396,8 @@ bool MemoryManager::page_in_from_inode(Region& region, unsigned page_index_in_re
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memset(page_buffer + nread, 0, PAGE_SIZE - nread);
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memset(page_buffer + nread, 0, PAGE_SIZE - nread);
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}
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}
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cli();
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cli();
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vmo_page = allocate_user_physical_page(ShouldZeroFill::No);
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vmobject_physical_page_entry = allocate_user_physical_page(ShouldZeroFill::No);
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if (vmo_page.is_null()) {
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if (vmobject_physical_page_entry.is_null()) {
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kprintf("MM: page_in_from_inode was unable to allocate a physical page\n");
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kprintf("MM: page_in_from_inode was unable to allocate a physical page\n");
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return false;
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return false;
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}
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}
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@ -87,16 +87,17 @@ int Region::commit()
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#ifdef MM_DEBUG
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#ifdef MM_DEBUG
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dbgprintf("MM: commit %u pages in Region %p (VMO=%p) at V%p\n", vmobject().page_count(), this, &vmobject(), vaddr().get());
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dbgprintf("MM: commit %u pages in Region %p (VMO=%p) at V%p\n", vmobject().page_count(), this, &vmobject(), vaddr().get());
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#endif
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#endif
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for (size_t i = first_page_index(); i <= last_page_index(); ++i) {
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for (size_t i = 0; i < page_count(); ++i) {
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if (!vmobject().physical_pages()[i].is_null())
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auto& vmobject_physical_page_entry = vmobject().physical_pages()[first_page_index() + i];
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if (!vmobject_physical_page_entry.is_null())
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continue;
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continue;
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auto physical_page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::Yes);
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auto physical_page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::Yes);
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if (!physical_page) {
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if (!physical_page) {
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kprintf("MM: commit was unable to allocate a physical page\n");
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kprintf("MM: commit was unable to allocate a physical page\n");
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return -ENOMEM;
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return -ENOMEM;
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}
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}
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vmobject().physical_pages()[i] = move(physical_page);
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vmobject_physical_page_entry = move(physical_page);
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remap_page(i - first_page_index());
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remap_page(i);
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}
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}
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return 0;
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return 0;
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}
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}
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