Re: [patch] mm: mlock: document scary-looking stack expansion mlock chain

From: Michel Lespinasse
Date: Wed Feb 20 2013 - 09:23:03 EST

On Wed, Feb 20, 2013 at 8:51 PM, Ric Mason <ric.masonn@xxxxxxxxx> wrote:
> On 02/01/2013 02:10 PM, Johannes Weiner wrote:
>> The fact that mlock calls get_user_pages, and get_user_pages might
>> call mlock when expanding a stack looks like a potential recursion.
> Why expand stack need call mlock? I can't find it in the codes, could you
> point out to me?

Its hidden in find_expand_vma(). Basically if the existing stack is
already mlocked, any additional stack expansions get mlocked as well.

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