ladybird/Kernel/VM/PrivateInodeVMObject.cpp
Tom b2a52f6208 Kernel: Implement lazy committed page allocation
By designating a committed page pool we can guarantee to have physical
pages available for lazy allocation in mappings. However, when forking
we will overcommit. The assumption is that worst-case it's better for
the fork to die due to insufficient physical memory on COW access than
the parent that created the region. If a fork wants to ensure that all
memory is available (trigger a commit) then it can use madvise.

This also means that fork now can gracefully fail if we don't have
enough physical pages available.
2021-01-01 23:43:44 +01:00

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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <Kernel/FileSystem/Inode.h>
#include <Kernel/VM/PrivateInodeVMObject.h>
namespace Kernel {
NonnullRefPtr<PrivateInodeVMObject> PrivateInodeVMObject::create_with_inode(Inode& inode)
{
return adopt(*new PrivateInodeVMObject(inode, inode.size()));
}
RefPtr<VMObject> PrivateInodeVMObject::clone()
{
return adopt(*new PrivateInodeVMObject(*this));
}
PrivateInodeVMObject::PrivateInodeVMObject(Inode& inode, size_t size)
: InodeVMObject(inode, size)
{
}
PrivateInodeVMObject::PrivateInodeVMObject(const PrivateInodeVMObject& other)
: InodeVMObject(other)
{
}
PrivateInodeVMObject::~PrivateInodeVMObject()
{
}
}