Re: [PATCH 00/59] Introduce credentials

[David Howells]

Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:

> > We get a number of things:
> > 
> >  (1) Multiple credential changes all happen simultaneously (setresuid() for
> >      example).  The new set of credentials is committed with a single RCU
> >      assignment.
> 
> Makes sense - except for the question of bounding memory utilisation.

Would it make sense to call synchronise_rcu() from commit_creds() or from
setuid()/setresuid()/setgroups()/etc. to make sure that some user process
doing:

	while (1)
		alter_credentials();

doesn't run the system out of memory by having loads of frees waiting in RCU's
queues because put_cred() uses call_rcu() to defer the destruction.

David
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