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

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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. :^)
This commit is contained in:
Andreas Kling 2020-05-06 21:11:38 +02:00
parent c633c1c2ea
commit 6fe83b0ac4
6 changed files with 27 additions and 20 deletions
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6
Kernel/VM/Region.cpp
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@ -368,7 +368,7 @@ PageFaultResponse Region::handle_zero_fault(size_t page_index_in_region)
auto page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::Yes);
if (page.is_null()) {
klog() << "MM: handle_zero_fault was unable to allocate a physical page";
return PageFaultResponse::ShouldCrash;
return PageFaultResponse::OutOfMemory;
}
#ifdef PAGE_FAULT_DEBUG
@ -401,7 +401,7 @@ PageFaultResponse Region::handle_cow_fault(size_t page_index_in_region)
auto page = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::No);
if (page.is_null()) {
klog() << "MM: handle_cow_fault was unable to allocate a physical page";
return PageFaultResponse::ShouldCrash;
return PageFaultResponse::OutOfMemory;
}
auto physical_page_to_copy = move(page_slot);
u8* dest_ptr = MM.quickmap_page(*page);
@ -463,7 +463,7 @@ PageFaultResponse Region::handle_inode_fault(size_t page_index_in_region)
vmobject_physical_page_entry = MM.allocate_user_physical_page(MemoryManager::ShouldZeroFill::No);
if (vmobject_physical_page_entry.is_null()) {
klog() << "MM: handle_inode_fault was unable to allocate a physical page";
return PageFaultResponse::ShouldCrash;
return PageFaultResponse::OutOfMemory;
}
u8* dest_ptr = MM.quickmap_page(*vmobject_physical_page_entry);