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Newsgroups: comp.os.386bsd.bugs Path: sserve!newshost.anu.edu.au!munnari.oz.au!constellation!osuunx.ucc.okstate.edu!moe.ksu.ksu.edu!ux1.cso.uiuc.edu!howland.reston.ans.net!wupost!uunet!mcsun!sun4nl!eur.nl!pk From: pk@cs.few.eur.nl (Paul Kranenburg) Subject: Re: ioctls and core dumps Message-ID: <1993Jun26.074010.5689@cs.few.eur.nl> Sender: news@cs.few.eur.nl Reply-To: pk@cs.few.eur.nl Organization: Erasmus University Rotterdam References: <1993Jun22.173715.6498@fac.com> <20cljmINNa7a@fstgds01.tu-graz.ac.at> Date: Sat, 26 Jun 1993 07:40:10 GMT Lines: 17 In <20cljmINNa7a@fstgds01.tu-graz.ac.at> chmr@edvz.tu-graz.ac.at (Christoph Robitschko) writes: [...] >VM system does with changes, since there are not supposed to be any. >If you change the protections with mprotect, the VM system does the >right thing. Not quite. Currently, upgrading permissions on a mmap'ed region of memory from, say, read-only to read-write, is not handled correctly by the VM system. As I've pointed out earlier, this can lead to a kernel deadlock or, in case the mmap'ed file resides on an NFS filesystem, to a panic due to IO without a process context or to silent failure of the write back because of misplaced credentials. -pk