Re: kernel 3.0: BUG: soft lockup: find_get_pages+0x51/0x110

From: Andrea Arcangeli
Date: Mon Oct 31 2011 - 13:54:34 EST


Hi Nai,

On Sat, Oct 22, 2011 at 01:07:11PM +0800, Nai Xia wrote:
> Yeah, anon_vma root lock is a big lock. And JFYI, actually I am doing
> some very nasty hacking on anon_vma and one of the side effects is
> breaking the root lock into pieces. But this area is pretty
> convolved by many racing conditions. I hope some day I will finally make
> my patch work and have your precious review of it. :-)

:) It's going to be not trivial, initially it was not a shared lock
but it wasn't safe that way (especially with migrate required a
reliable rmap_walk) and using a shared lock across all
same_anon_vma/same_vma lists was the only way to be safe and solve the
races.
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