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Date: Thu, 28 Aug 2008 13:28:33 -0700 From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> To: Alan Cox <alan@...rguk.ukuu.org.uk> Cc: David Howells <dhowells@...hat.com>, linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org Subject: Re: [PATCH 00/59] Introduce credentials On Thu, Aug 28, 2008 at 10:45:03AM +0100, Alan Cox wrote: > On Thu, 28 Aug 2008 10:19:44 +0100 > David Howells <dhowells@...hat.com> wrote: > > > Alan Cox <alan@...rguk.ukuu.org.uk> 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. > > I suspect you to - or every "nth" event - building up a small queue as > would occur in normal usage probably isn't a problem. Makes sense to me, given that we should not expect real-time determinism out of alter_credentials(). ;-) Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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