Date: Fri, 30 Apr 2004 22:13:17 -0400 (EDT) From: Robert Watson <rwatson@FreeBSD.org> To: Brian Fundakowski Feldman <green@FreeBSD.org> Cc: Pawel Jakub Dawidek <pjd@FreeBSD.org> Subject: Re: LOR: /sys/ufs/ffs/ffs_snapshot.c:1893 /sys/vm/vm_map.c:2206 Message-ID: <Pine.NEB.3.96L.1040430221157.63854C-100000@fledge.watson.org> In-Reply-To: <200404301437.i3UEbnvM076898@green.homeunix.org>
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On Fri, 30 Apr 2004, Brian Fundakowski Feldman wrote: > I haven't seen it myself, but it seems like it's only going to happen > sometimes (when a full page is freed). There's really no technical > reason you'd ever want to do a free(9) with locks held, so I suggest > fixing it in the straightforward way. While I sympathize with this point, I don't think it's realistic to assert that free() will never be called while helding a lock. Once the mbuf allocator backs into regular malloc() and free(); the network stack relies on being able to perform wait-free allocation and free while locks are held, since it uses locks as a light-weight form of reference-counting. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research
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