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https://github.com/RGBCube/serenity
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b2a52f6208
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.
53 lines
2.1 KiB
C++
53 lines
2.1 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/Bitmap.h>
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#include <Kernel/UnixTypes.h>
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#include <Kernel/VM/InodeVMObject.h>
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namespace Kernel {
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class SharedInodeVMObject final : public InodeVMObject {
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AK_MAKE_NONMOVABLE(SharedInodeVMObject);
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public:
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static NonnullRefPtr<SharedInodeVMObject> create_with_inode(Inode&);
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virtual RefPtr<VMObject> clone() override;
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private:
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virtual bool is_shared_inode() const override { return true; }
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explicit SharedInodeVMObject(Inode&, size_t);
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explicit SharedInodeVMObject(const SharedInodeVMObject&);
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virtual const char* class_name() const override { return "SharedInodeVMObject"; }
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SharedInodeVMObject& operator=(const SharedInodeVMObject&) = delete;
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};
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}
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