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Kernel: Make Region::try_create_user_accessible() OOM-safe

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Previously we would simply assume that Region allocation always
succeeded. There is still one such assumption when splitting user
regions inside a Space. That will be dealt with in a separate commit.
This commit is contained in:
Andreas Kling 2021-07-11 18:07:12 +02:00
parent 241bbce264
commit cac557eee0
3 changed files with 33 additions and 14 deletions
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21
Kernel/VM/Region.cpp
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@ -83,8 +83,12 @@ OwnPtr<Region> Region::clone(Process& new_owner)
VERIFY(vmobject().is_shared_inode());
// Create a new region backed by the same VMObject.
auto region = Region::create_user_accessible(
auto region = Region::try_create_user_accessible(
&new_owner, m_range, m_vmobject, m_offset_in_vmobject, m_name ? m_name->try_clone() : OwnPtr<KString> {}, access(), m_cacheable ? Cacheable::Yes : Cacheable::No, m_shared);
if (!region) {
dbgln("Region::clone: Unable to allocate new Region");
return nullptr;
}
if (m_vmobject->is_anonymous())
region->copy_purgeable_page_ranges(*this);
region->set_mmap(m_mmap);
@ -102,8 +106,12 @@ OwnPtr<Region> Region::clone(Process& new_owner)
// Set up a COW region. The parent (this) region becomes COW as well!
remap();
auto clone_region = Region::create_user_accessible(
auto clone_region = Region::try_create_user_accessible(
&new_owner, m_range, vmobject_clone.release_nonnull(), m_offset_in_vmobject, m_name ? m_name->try_clone() : OwnPtr<KString> {}, access(), m_cacheable ? Cacheable::Yes : Cacheable::No, m_shared);
if (!clone_region) {
dbgln("Region::clone: Unable to allocate new Region for COW");
return nullptr;
}
if (m_vmobject->is_anonymous())
clone_region->copy_purgeable_page_ranges(*this);
if (m_stack) {
@ -208,13 +216,14 @@ size_t Region::amount_shared() const
return bytes;
}
NonnullOwnPtr<Region> Region::create_user_accessible(Process* owner, const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable cacheable, bool shared)
OwnPtr<Region> Region::try_create_user_accessible(Process* owner, const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable cacheable, bool shared)
{
auto region = adopt_own_if_nonnull(new (nothrow) Region(range, move(vmobject), offset_in_vmobject, move(name), access, cacheable, shared));
if (region && owner)
if (!region)
return nullptr;
if (owner)
region->m_owner = owner->make_weak_ptr();
// FIXME: Return OwnPtr and propagate failure, currently there are too many assumptions made by down stream callers.
return region.release_nonnull();
return region;
}
OwnPtr<Region> Region::create_kernel_only(const Range& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable cacheable)