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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
View file

@ -83,8 +83,12 @@ OwnPtr<Region> Region::clone(Process& new_owner)
VERIFY(vmobject().is_shared_inode()); VERIFY(vmobject().is_shared_inode());
// Create a new region backed by the same VMObject. // 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); &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()) if (m_vmobject->is_anonymous())
region->copy_purgeable_page_ranges(*this); region->copy_purgeable_page_ranges(*this);
region->set_mmap(m_mmap); 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! // Set up a COW region. The parent (this) region becomes COW as well!
remap(); 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); &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()) if (m_vmobject->is_anonymous())
clone_region->copy_purgeable_page_ranges(*this); clone_region->copy_purgeable_page_ranges(*this);
if (m_stack) { if (m_stack) {
@ -208,13 +216,14 @@ size_t Region::amount_shared() const
return bytes; 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)); 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(); 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;
return region.release_nonnull();
} }
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) 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)

2
Kernel/VM/Region.h
View file

@ -49,7 +49,7 @@ public:
Yes, Yes,
}; };
static NonnullOwnPtr<Region> create_user_accessible(Process*, const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable, bool shared); static OwnPtr<Region> try_create_user_accessible(Process*, const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable, bool shared);
static OwnPtr<Region> create_kernel_only(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable = Cacheable::Yes); static OwnPtr<Region> create_kernel_only(const Range&, NonnullRefPtr<VMObject>, size_t offset_in_vmobject, OwnPtr<KString> name, Region::Access access, Cacheable = Cacheable::Yes);
~Region(); ~Region();

24
Kernel/VM/Space.cpp
View file

@ -145,8 +145,11 @@ Optional<Range> Space::allocate_range(VirtualAddress vaddr, size_t size, size_t
Region& Space::allocate_split_region(const Region& source_region, const Range& range, size_t offset_in_vmobject) Region& Space::allocate_split_region(const Region& source_region, const Range& range, size_t offset_in_vmobject)
{ {
auto& region = add_region(Region::create_user_accessible( auto new_region = Region::try_create_user_accessible(
m_process, range, source_region.vmobject(), offset_in_vmobject, KString::try_create(source_region.name()), source_region.access(), source_region.is_cacheable() ? Region::Cacheable::Yes : Region::Cacheable::No, source_region.is_shared())); m_process, range, source_region.vmobject(), offset_in_vmobject, KString::try_create(source_region.name()), source_region.access(), source_region.is_cacheable() ? Region::Cacheable::Yes : Region::Cacheable::No, source_region.is_shared());
// FIXME: Handle !new_region (by propagating ENOMEM)
VERIFY(new_region);
auto& region = add_region(new_region.release_nonnull());
region.set_syscall_region(source_region.is_syscall_region()); region.set_syscall_region(source_region.is_syscall_region());
region.set_mmap(source_region.is_mmap()); region.set_mmap(source_region.is_mmap());
region.set_stack(source_region.is_stack()); region.set_stack(source_region.is_stack());
@ -164,10 +167,12 @@ KResultOr<Region*> Space::allocate_region(Range const& range, StringView name, i
auto vmobject = AnonymousVMObject::try_create_with_size(range.size(), strategy); auto vmobject = AnonymousVMObject::try_create_with_size(range.size(), strategy);
if (!vmobject) if (!vmobject)
return ENOMEM; return ENOMEM;
auto region = Region::create_user_accessible(m_process, range, vmobject.release_nonnull(), 0, KString::try_create(name), prot_to_region_access_flags(prot), Region::Cacheable::Yes, false); auto region = Region::try_create_user_accessible(m_process, range, vmobject.release_nonnull(), 0, KString::try_create(name), prot_to_region_access_flags(prot), Region::Cacheable::Yes, false);
if (!region)
return ENOMEM;
if (!region->map(page_directory())) if (!region->map(page_directory()))
return ENOMEM; return ENOMEM;
return &add_region(move(region)); return &add_region(region.release_nonnull());
} }
KResultOr<Region*> Space::allocate_region_with_vmobject(Range const& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, StringView name, int prot, bool shared) KResultOr<Region*> Space::allocate_region_with_vmobject(Range const& range, NonnullRefPtr<VMObject> vmobject, size_t offset_in_vmobject, StringView name, int prot, bool shared)
@ -187,12 +192,17 @@ KResultOr<Region*> Space::allocate_region_with_vmobject(Range const& range, Nonn
return EINVAL; return EINVAL;
} }
offset_in_vmobject &= PAGE_MASK; offset_in_vmobject &= PAGE_MASK;
auto& region = add_region(Region::create_user_accessible(m_process, range, move(vmobject), offset_in_vmobject, KString::try_create(name), prot_to_region_access_flags(prot), Region::Cacheable::Yes, shared)); auto region = Region::try_create_user_accessible(m_process, range, move(vmobject), offset_in_vmobject, KString::try_create(name), prot_to_region_access_flags(prot), Region::Cacheable::Yes, shared);
if (!region.map(page_directory())) { if (!region) {
dbgln("allocate_region_with_vmobject: Unable to allocate Region");
return nullptr;
}
auto& region_ref = add_region(region.release_nonnull());
if (!region_ref.map(page_directory())) {
// FIXME: What is an appropriate error code here, really? // FIXME: What is an appropriate error code here, really?
return ENOMEM; return ENOMEM;
} }
return &region; return &region_ref;
} }
bool Space::deallocate_region(Region& region) bool Space::deallocate_region(Region& region)