Date: Fri, 31 Jul 2009 10:27:16 -0400 From: John Baldwin <jhb@freebsd.org> To: Attilio Rao <attilio@freebsd.org> Cc: freebsd-current@freebsd.org, pjd@freebsd.org Subject: Re: panic: mutex Giant owned at .../base/head/sys/kern/kern_exit.c:131 Message-ID: <200907311027.16492.jhb@freebsd.org> In-Reply-To: <3bbf2fe10907310711v4ed3ba48jac84ea99d863d0a9@mail.gmail.com> References: <152E0401-8750-4363-85D8-F058BD87C150@mac.com> <200907310853.52946.jhb@freebsd.org> <3bbf2fe10907310711v4ed3ba48jac84ea99d863d0a9@mail.gmail.com>
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On Friday 31 July 2009 10:11:25 am Attilio Rao wrote: > 2009/7/31 John Baldwin <jhb@freebsd.org>: > > On Friday 31 July 2009 2:36:46 am Marcel Moolenaar wrote: > >> All, > >> > >> I got the following panic after I had to import my ZFS file system on > >> ia64. > >> The following panic happened when executing "zpool import": > >> > >> panic: mutex Giant owned at /nfs/freebsd/base/head/sys/kern/ > >> kern_exit.c:131 > >> cpuid = 0 > >> KDB: enter: panic > > > > It looks like ZFS doesn't actually ever check if any of the namei lookups it > > does internally return with Giant locked. For example, it doesn't check > > NDHASGIANT() in lookupnameat(). Fixing this may be a bit of work as I'm not > > sure it is safe to drop Giant right after the namei(). If it is because the > > end vnode's returned are always MPSAFE then that fix is easy. If not, then > > Giant needs to be held until the code stops frobbing the vnode returned from > > the lookup. > > NDHASGIANT() reflects the locking of the mountpoint where the vnode is > on so you need to size it in regard of what the namei() consumer is > going to expect in terms of locking with such vnode/mountpoint. True, but in this case the Giant lock that is leaked is locked in namei(). If you have LOCKPARENT set and you lookup your / then the parent vnode may be from a different !MPSAFE filesystem even if your filesystem is safe, yes? -- John Baldwin
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