Date: Sun, 16 Nov 2014 11:31:58 -0700 From: Ian Lepore <ian@FreeBSD.org> To: Mark R V Murray <markm@FreeBSD.org> Cc: Hans Petter Selasky <hps@selasky.org>, Adrian Chadd <adrian@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, Steve Kargl <sgk@troutmask.apl.washington.edu>, Dag-Erling Sm?rgrav <des@freebsd.org> Subject: Re: USB locks up system -- WAS Re: shutdown or acpi problem Message-ID: <1416162718.4781.192.camel@revolution.hippie.lan> In-Reply-To: <F0B9570C-BADD-4843-AE91-66CAB0B5DE85@FreeBSD.org> References: <20141112224212.GA14013@troutmask.apl.washington.edu> <20141113172533.GA18690@troutmask.apl.washington.edu> <20141113180332.GA18990@troutmask.apl.washington.edu> <20141113181515.GA19117@troutmask.apl.washington.edu> <546515BF.6030508@selasky.org> <20141113212206.GA20802@troutmask.apl.washington.edu> <20141116054141.GA33186@troutmask.apl.washington.edu> <CAJ-Vmo=8oQdi_5um3ck%2BQwb=4KL2QfHE=ykQ2mNTJc5QerOEuw@mail.gmail.com> <20141116175102.GA35649@troutmask.apl.washington.edu> <D5925789-834A-42C8-9854-2E055592DA46@FreeBSD.org> <1416162070.4781.186.camel@revolution.hippie.lan> <F0B9570C-BADD-4843-AE91-66CAB0B5DE85@FreeBSD.org>
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On Sun, 2014-11-16 at 18:23 +0000, Mark R V Murray wrote: > > On 16 Nov 2014, at 18:21, Ian Lepore <ian@FreeBSD.org> wrote: > >=20 > > On Sun, 2014-11-16 at 18:17 +0000, Mark R V Murray wrote: > >>> On 16 Nov 2014, at 17:51, Steve Kargl <sgk@troutmask.apl.washington= .edu> wrote: > >>>=20 > >>> Is there a 'random: device_detach():' missing between the 'umass0' > >>> and 'da0' messages in the last 4 lines. > >>=20 > >> No. At attach time, the RNG grabs some probe entropy. At detach time= it does nothing. > >>=20 > >> M > >=20 > > And yet... Steve has gathered evidence that the system bricks when a > > device is detached with the new entropy-gathering code and doesn't do= so > > prior to that code. What else is the new code doing around detach ti= me? >=20 > Nothing, except possibly harvesting interrupt entropy. I=A2ll promise t= o be > astonished if this is other-than-harmless. >=20 > I=A2d be more suspicious of the harvester thread, but I still can=A2t s= ee how > its hurting :-( >=20 > M The point I'm trying to make here is that you trimmed away the important part of the prior messages and replied only to the part where Steve's debugging efforts were somewhat speculating. The non-speculative part was where he bisected the failure to an exact commit: > > > The problem is caused > > > by r273872. This is the recent random device patch. I have no > > > idea why removing a usb device would cause the system to lock > > > up other than random is probably trying to harvest some entropy. -- Ian
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