From: Charles Forsyth <forsyth@terzarima.net>
To: 9fans@9fans.net
Subject: Re: [9fans] Race condition in /sys/src/9/pc/trap.c?
Date: Fri, 31 Jul 2009 20:31:39 +0100 [thread overview]
Message-ID: <8ab5e568a932c69389783454382c2401@terzarima.net> (raw)
In-Reply-To: <f390245ec5802e1703b4bd6a6b15a6c3@gmx.de>
>but my testcase crashes a uniprocessor system, so here is no
>waiting for mmuflushes on other processors going on.
it ensures mmuflushes in all other processes (sharing that segment) as well.
in fact, the crash you describe just emphasises that point:
the page reference no longer exists, hence the fault.
the problem (which frankly doesn't bother me) is that fault386
is being overly cautious in assuming that a page fault that occurs
in system mode but can't map a page successfully is necessarily a kernel bug:
that's not true. it could just note the process instead.
(it doesn't bother me because since unix days i've seen less than a handful
of programs that SHRINK their existing data segments, and i think that's the
only case that can cause the panic you're seeing.)
next prev parent reply other threads:[~2009-07-31 19:31 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-30 4:03 Matthew J Jones
2009-07-30 11:27 ` erik quanstrom
2009-07-30 14:25 ` Elizabeth Jones
2009-07-30 14:37 ` Sape Mullender
2009-07-30 15:01 ` cinap_lenrek
2009-07-30 15:24 ` cinap_lenrek
2009-07-30 15:17 ` cinap_lenrek
2009-07-30 15:54 ` Charles Forsyth
2009-07-31 13:07 ` Charles Forsyth
2009-07-31 13:28 ` Richard Miller
2009-07-31 17:13 ` cinap_lenrek
2009-07-31 18:00 ` erik quanstrom
2009-07-31 18:08 ` Devon H. O'Dell
2009-07-31 18:18 ` erik quanstrom
2009-07-31 18:35 ` Devon H. O'Dell
2009-07-31 21:52 ` cinap_lenrek
2009-07-31 19:31 ` Charles Forsyth [this message]
2009-07-31 19:40 ` erik quanstrom
2009-07-31 20:41 ` Charles Forsyth
2009-07-30 15:20 ` erik quanstrom
2009-07-30 14:39 ` erik quanstrom
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