[Linux-ia64] Re: switch_mm race condition with Ingo's scheduler

From: David Mosberger <davidm_at_napali.hpl.hp.com>
Date: 2002-07-13 03:02:43
>>>>> On Fri, 12 Jul 2002 18:47:58 +0200, Erich Focht <efocht@ess.nec.de> said:

  Erich> But then other processors would continue using the old TLBs
  Erich> maybe of tasks which died. The problem is that we need to do
  Erich> a TLB flush on all CPUs when wrapping around the
  Erich> context. Otherwise we might reuse the context number of a
  Erich> recently exited process and on other CPUs some of its TLB
  Erich> entries may survive until the new task switches CPUs. Hard to
  Erich> debug, probably...

But the only time you might reuse an old context number is when you
allocate one.  Yes, you will have old entries hanging around in the
TLB for a while, but you _know_ that the corresponding tasks already
died and you also know that you'll flush the TLB before re-using one
of those context numbers.

Received on Fri Jul 12 10:04:20 2002

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