From 12300b7d0b1b3735bb1c413ee5d8ac22163ac385 Mon Sep 17 00:00:00 2001
From: Idan Horowitz <idan.horowitz@gmail.com>
Date: Sat, 27 Aug 2022 19:00:57 +0300
Subject: [PATCH] Kernel: Dump OOM debug info after releasing the MM global
 data lock

Otherwise we would be holding the MM global data lock and the Process
address space locks in reversed order to the rest of the system, which
can lead to deadlocks.
---
 Kernel/Memory/MemoryManager.cpp | 41 +++++++++++++++++----------------
 1 file changed, 21 insertions(+), 20 deletions(-)

diff --git a/Kernel/Memory/MemoryManager.cpp b/Kernel/Memory/MemoryManager.cpp
index 5d108e26bf..4db696a92e 100644
--- a/Kernel/Memory/MemoryManager.cpp
+++ b/Kernel/Memory/MemoryManager.cpp
@@ -829,28 +829,9 @@ ErrorOr<NonnullOwnPtr<Region>> MemoryManager::allocate_kernel_region_with_vmobje
 ErrorOr<CommittedPhysicalPageSet> MemoryManager::commit_physical_pages(size_t page_count)
 {
     VERIFY(page_count > 0);
-    return m_global_data.with([&](auto& global_data) -> ErrorOr<CommittedPhysicalPageSet> {
+    auto result = m_global_data.with([&](auto& global_data) -> ErrorOr<CommittedPhysicalPageSet> {
         if (global_data.system_memory_info.physical_pages_uncommitted < page_count) {
             dbgln("MM: Unable to commit {} pages, have only {}", page_count, global_data.system_memory_info.physical_pages_uncommitted);
-
-            Process::for_each([&](Process const& process) {
-                size_t amount_resident = 0;
-                size_t amount_shared = 0;
-                size_t amount_virtual = 0;
-                process.address_space().with([&](auto& space) {
-                    amount_resident = space->amount_resident();
-                    amount_shared = space->amount_shared();
-                    amount_virtual = space->amount_virtual();
-                });
-                dbgln("{}({}) resident:{}, shared:{}, virtual:{}",
-                    process.name(),
-                    process.pid(),
-                    amount_resident / PAGE_SIZE,
-                    amount_shared / PAGE_SIZE,
-                    amount_virtual / PAGE_SIZE);
-                return IterationDecision::Continue;
-            });
-
             return ENOMEM;
         }
 
@@ -858,6 +839,26 @@ ErrorOr<CommittedPhysicalPageSet> MemoryManager::commit_physical_pages(size_t pa
         global_data.system_memory_info.physical_pages_committed += page_count;
         return CommittedPhysicalPageSet { {}, page_count };
     });
+    if (result.is_error()) {
+        Process::for_each([&](Process const& process) {
+            size_t amount_resident = 0;
+            size_t amount_shared = 0;
+            size_t amount_virtual = 0;
+            process.address_space().with([&](auto& space) {
+                amount_resident = space->amount_resident();
+                amount_shared = space->amount_shared();
+                amount_virtual = space->amount_virtual();
+            });
+            dbgln("{}({}) resident:{}, shared:{}, virtual:{}",
+                process.name(),
+                process.pid(),
+                amount_resident / PAGE_SIZE,
+                amount_shared / PAGE_SIZE,
+                amount_virtual / PAGE_SIZE);
+            return IterationDecision::Continue;
+        });
+    }
+    return result;
 }
 
 void MemoryManager::uncommit_physical_pages(Badge<CommittedPhysicalPageSet>, size_t page_count)