[PATCH 1/2] Re: Major breakage in linux-git on x86_64, oom killergoes on rampage

[Pavel Roskin]

Hello again,

here's the solution.  The x86_64 specific portion will be posted as a
separate patch.

> Now the system boot goes a little further and then the kernel reports a
> BUG in mm/memory.c:985.  Apparently __handle_mm_fault() returns
> something unexpected.

I'm getting a BUG in mm/memory.c:985.  The unexpected value is 18 or
VM_FAULT_MINOR|VM_FAULT_WRITE.  As it turns out, __handle_mm_fault()
never returns VM_FAULT_WRITE, but in combination with VM_FAULT_MINOR.
Apparently, that's what was meant, and the fallthrough to case
VM_FAULT_MINOR is an indication of that.

Signed-off-by: Pavel Roskin <proski@xxxxxxx>

diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -963,7 +963,7 @@ int get_user_pages(struct task_struct *t
 				spin_unlock(&mm->page_table_lock);
 				switch (__handle_mm_fault(mm, vma, start,
 							write_access)) {
-				case VM_FAULT_WRITE:
+				case VM_FAULT_WRITE|VM_FAULT_MINOR:
 					/*
 					 * do_wp_page has broken COW when
 					 * necessary, even if maybe_mkwrite

-- 
Regards,
Pavel Roskin

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