Date: Mon, 28 May 2007 23:06:24 +0200 From: Attilio Rao <attilio@FreeBSD.org> To: Tor Egge <Tor.Egge@cvsup.no.freebsd.org> Cc: jroberson@chesapeake.net, current@freebsd.org Subject: Re: Panic on -CURRENT after LDT changes Message-ID: <465B4450.90800@FreeBSD.org> In-Reply-To: <20070528.162023.41711345.Tor.Egge@cvsup.no.freebsd.org> References: <1180138048.94117.17.camel@shumai.marcuscom.com> <465780A3.8040603@FreeBSD.org> <1180140483.94117.24.camel@shumai.marcuscom.com> <20070528.162023.41711345.Tor.Egge@cvsup.no.freebsd.org>
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Tor Egge wrote: > > Finally, I found that i386_ldt_grow() called smp_rendezvous() without > temporarily unlocking dt_lock. That caused a deadlock. Adding a temporary > unlock of dt_lock seems to solve the problem for me. Effectively, there is the need to release the dt_lock before to call smp_rendezvous() beacause other threads running on other CPUs will contest on this lock and it will cause a deadlock (since their curthreads don't hold the lock). I think that mantaining the current locking requirements for i386_ldt_grow() is still good, since, for how it is used, this is the lighter approach. I will add release/unrelease around smp_rendezvous() too. Thanks for the catch, Attilio
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