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2d1a651e0a
This patch changes the semantics of purgeable memory. - AnonymousVMObject now has a "purgeable" flag. It can only be set when constructing the object. (Previously, all anonymous memory was effectively purgeable.) - AnonymousVMObject now has a "volatile" flag. It covers the entire range of physical pages. (Previously, we tracked ranges of volatile pages, effectively making it a page-level concept.) - Non-volatile objects maintain a physical page reservation via the committed pages mechanism, to ensure full coverage for page faults. - When an object is made volatile, it relinquishes any unused committed pages immediately. If later made non-volatile again, we then attempt to make a new committed pages reservation. If this fails, we return ENOMEM to userspace. mmap() now creates purgeable objects if passed the MAP_PURGEABLE option together with MAP_ANONYMOUS. anon_create() memory is always purgeable.
73 lines
2.4 KiB
C++
73 lines
2.4 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/NonnullRefPtrVector.h>
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#include <Kernel/Arch/x86/InterruptDisabler.h>
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#include <Kernel/Process.h>
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#include <Kernel/VM/AnonymousVMObject.h>
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#include <Kernel/VM/InodeVMObject.h>
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#include <Kernel/VM/MemoryManager.h>
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namespace Kernel {
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KResultOr<FlatPtr> Process::sys$purge(int mode)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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REQUIRE_NO_PROMISES;
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if (!is_superuser())
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return EPERM;
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size_t purged_page_count = 0;
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if (mode & PURGE_ALL_VOLATILE) {
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NonnullRefPtrVector<AnonymousVMObject> vmobjects;
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{
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KResult result(KSuccess);
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MM.for_each_vmobject([&](auto& vmobject) {
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if (vmobject.is_anonymous()) {
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// In the event that the append fails, only attempt to continue
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// the purge if we have already appended something successfully.
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if (!vmobjects.try_append(vmobject) && vmobjects.is_empty()) {
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result = ENOMEM;
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return IterationDecision::Break;
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}
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}
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return IterationDecision::Continue;
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});
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if (result.is_error())
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return result.error();
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}
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for (auto& vmobject : vmobjects) {
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purged_page_count += vmobject.purge();
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}
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}
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if (mode & PURGE_ALL_CLEAN_INODE) {
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NonnullRefPtrVector<InodeVMObject> vmobjects;
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{
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KResult result(KSuccess);
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MM.for_each_vmobject([&](auto& vmobject) {
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if (vmobject.is_inode()) {
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// In the event that the append fails, only attempt to continue
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// the purge if we have already appended something successfully.
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if (!vmobjects.try_append(static_cast<InodeVMObject&>(vmobject)) && vmobjects.is_empty()) {
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result = ENOMEM;
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return IterationDecision::Break;
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}
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}
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return IterationDecision::Continue;
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});
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if (result.is_error())
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return result.error();
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}
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for (auto& vmobject : vmobjects) {
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purged_page_count += vmobject.release_all_clean_pages();
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}
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}
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return purged_page_count;
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}
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}
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