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Date: Thu, 02 Jan 2003 13:51:54 -0600
From: "Alan L. Cox" <alc@imimic.com>
Organization: iMimic Networking, Inc.
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To: John Baldwin <jhb@FreeBSD.org>
Cc: Nate Lawson <nate@root.org>, cvs-committers@freebsd.org,
	cvs-all@freebsd.org, Alan Cox <alc@FreeBSD.org>
Subject: Re: cvs commit: src/sys/nfsclient nfs_vnops.c
References: <XFMail.20030102124236.jhb@FreeBSD.org>
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John Baldwin wrote:
> ...
> Unless you use M_NOWAIT (highly undesirable in mose cases), you need to
> not hold locks across malloc() anyways as it can sleep.  One should be
> able to hold locks across free() without problems however.  I would rather
> require callers of the code in question to hold Giant for now rather than
> add in hacks that have to be cleaned up later on.
> 

In general, yes.  The vnode interlock is, however, a special case.  Any
form of malloc() or free() while holding a vnode interlock will cause a
reversal.  This stems from the intertwining of vm objects and vnodes.

Regards,
Alan

P.S. If someone knows a good place to document this, please do.

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