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From: John Polstra <jdp@FreeBSD.ORG>
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Date: Thu, 8 Oct 1998 17:24:51 -0700 (PDT)
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To: cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG
Subject: cvs commit: src/sys/vm vm_zone.c
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jdp         1998/10/08 17:24:51 PDT

  Modified files:
    sys/vm               vm_zone.c 
  Log:
  Fix a panic on SMP systems, caused by sleeping while holding a
  simple-lock.
  
  The reviewer raises the following caveat: "I believe these changes
  open a non-critical race condition when adding memory to the pool
  for the zone. I think what will happen is that you could have two
  threads that are simultaneously adding additional memory when the
  pool runs out. This appears to not be a problem, however, since
  the re-aquisition of the lock will protect the list pointers."
  The submitter agrees that the race is non-critical, and points out
  that it already existed for the non-SMP case.  He suggests that
  perhaps a sleep lock (using the lock manager) should be used to
  close that race.  This might be worth revisiting after 3.0 is
  released.
  
  Reviewed by:	dg (David Greenman)
  Submitted by:	tegge (Tor Egge)
  
  Revision  Changes    Path
  1.22      +13 -1     src/sys/vm/vm_zone.c