[PATCH 03/16] mm: check rb_subtree_gap correctness

[Michel Lespinasse]

On Fri, Nov 9, 2012 at 6:13 AM, Sasha Levin <levinsasha928 at gmail.com> wrote:
> While fuzzing with trinity inside a KVM tools (lkvm) guest, using today's -next
> kernel, I'm getting these:
>
> [  117.007714] free gap 7fba0dd1c000, correct 7fba0dcfb000
> [  117.019773] map_count 750 rb -1
> [  117.028362] ------------[ cut here ]------------
> [  117.029813] kernel BUG at mm/mmap.c:439!
>
> Note that they are very easy to reproduce.

Thanks for the report. I had trouble reproducing this on Friday, but
after Hugh came up with an easy test case I think I have it figured
out. I sent out a proposed fix as "[PATCH 0/3] fix missing
rb_subtree_gap updates on vma insert/erase". Let's follow up the
discussion there if necessary.

Cheers,

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.