Kernel: Crash the current process on OOM (instead of panicking kernel)

This patch adds PageFaultResponse::OutOfMemory which informs the fault
handler that we were unable to allocate a necessary physical page and
cannot continue.

In response to this, the kernel will crash the current process. Because
we are OOM, we can't symbolicate the crash like we normally would
(since the ELF symbolication code needs to allocate), so we also
communicate to Process::crash() that we're out of memory.

Now we can survive "allocate 300 MB" (only the allocate process dies.)
This is definitely not perfect and can easily end up killing a random
innocent other process who happened to allocate one page at the wrong
time, but it's a *lot* better than panicking on OOM. :^)

1 files changed, 12 insertions, 8 deletions

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index 616fdff75e..2f25867518 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -1540,21 +1540,25 @@ int Process::sys$sigreturn(RegisterState& registers)
     return smuggled_eax;
 }
 
-void Process::crash(int signal, u32 eip)
+void Process::crash(int signal, u32 eip, bool out_of_memory)
 {
     ASSERT_INTERRUPTS_DISABLED();
     ASSERT(!is_dead());
     ASSERT(Process::current == this);
 
-    if (eip >= 0xc0000000 && g_kernel_symbols_available) {
-        auto* symbol = symbolicate_kernel_address(eip);
-        dbg() << "\033[31;1m" << String::format("%p", eip) << "  " << (symbol ? demangle(symbol->name) : "(k?)") << " +" << (symbol ? eip - symbol->address : 0) << "\033[0m\n";
-    } else if (auto elf_bundle = this->elf_bundle()) {
-        dbg() << "\033[31;1m" << String::format("%p", eip) << "  " << elf_bundle->elf_loader->symbolicate(eip) << "\033[0m\n";
+    if (out_of_memory) {
+        dbg() << "\033[31;1mOut of memory\033[m, killing: " << *this;
     } else {
-        dbg() << "\033[31;1m" << String::format("%p", eip) << "  (?)\033[0m\n";
+        if (eip >= 0xc0000000 && g_kernel_symbols_available) {
+            auto* symbol = symbolicate_kernel_address(eip);
+            dbg() << "\033[31;1m" << String::format("%p", eip) << "  " << (symbol ? demangle(symbol->name) : "(k?)") << " +" << (symbol ? eip - symbol->address : 0) << "\033[0m\n";
+        } else if (auto elf_bundle = this->elf_bundle()) {
+            dbg() << "\033[31;1m" << String::format("%p", eip) << "  " << elf_bundle->elf_loader->symbolicate(eip) << "\033[0m\n";
+        } else {
+            dbg() << "\033[31;1m" << String::format("%p", eip) << "  (?)\033[0m\n";
+        }
+        dump_backtrace();
     }
-    dump_backtrace();
     m_termination_signal = signal;
     dump_regions();
     ASSERT(is_ring3());