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Kernel: Don't hog the MM lock while unmapping regions

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We were holding the MM lock across all of the region unmapping code.
This was previously necessary since the quickmaps used during unmapping
required holding the MM lock.

Now that it's no longer necessary, we can leave the MM lock alone here.
This commit is contained in:
Andreas Kling 2022-08-23 12:38:17 +02:00
parent dc9d2c1b10
commit d6ef18f587
Notes: sideshowbarker 2024-07-17 07:49:01 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/d6ef18f587
3 changed files with 5 additions and 8 deletions
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3
Kernel/Memory/AddressSpace.cpp
View file

@ -341,10 +341,9 @@ void AddressSpace::remove_all_regions(Badge<Process>)
VERIFY(Thread::current() == g_finalizer);
{
SpinlockLocker pd_locker(m_page_directory->get_lock());
SpinlockLocker mm_locker(s_mm_lock);
m_region_tree.with([&](auto& region_tree) {
for (auto& region : region_tree.regions())
region.unmap_with_locks_held(ShouldFlushTLB::No, pd_locker, mm_locker);
region.unmap_with_locks_held(ShouldFlushTLB::No, pd_locker);
});
}

8
Kernel/Memory/Region.cpp
View file

@ -70,8 +70,7 @@ Region::~Region()
if (!is_readable() && !is_writable() && !is_executable()) {
// If the region is "PROT_NONE", we didn't map it in the first place.
} else {
SpinlockLocker mm_locker(s_mm_lock);
unmap_with_locks_held(ShouldFlushTLB::Yes, pd_locker, mm_locker);
unmap_with_locks_held(ShouldFlushTLB::Yes, pd_locker);
VERIFY(!m_page_directory);
}
}
@ -268,11 +267,10 @@ void Region::unmap(ShouldFlushTLB should_flush_tlb)
if (!m_page_directory)
return;
SpinlockLocker pd_locker(m_page_directory->get_lock());
SpinlockLocker mm_locker(s_mm_lock);
unmap_with_locks_held(should_flush_tlb, pd_locker, mm_locker);
unmap_with_locks_held(should_flush_tlb, pd_locker);
}
void Region::unmap_with_locks_held(ShouldFlushTLB should_flush_tlb, SpinlockLocker<RecursiveSpinlock>&, SpinlockLocker<RecursiveSpinlock>&)
void Region::unmap_with_locks_held(ShouldFlushTLB should_flush_tlb, SpinlockLocker<RecursiveSpinlock>&)
{
if (!m_page_directory)
return;

2
Kernel/Memory/Region.h
View file

@ -183,7 +183,7 @@ public:
void set_page_directory(PageDirectory&);
ErrorOr<void> map(PageDirectory&, ShouldFlushTLB = ShouldFlushTLB::Yes);
void unmap(ShouldFlushTLB = ShouldFlushTLB::Yes);
void unmap_with_locks_held(ShouldFlushTLB, SpinlockLocker<RecursiveSpinlock>& pd_locker, SpinlockLocker<RecursiveSpinlock>& mm_locker);
void unmap_with_locks_held(ShouldFlushTLB, SpinlockLocker<RecursiveSpinlock>& pd_locker);
void remap();