Date: Tue, 7 Jul 1998 10:57:45 -0500 From: "Alton, Matthew" <Matthew.Alton@anheuser-busch.com> To: "'Erick Engelke'" <erick@dark.uwaterloo.ca> Cc: "'hackers@freebsd.org'" <hackers@FreeBSD.ORG>, "'freebsd-fs@freebsd.org'" <freebsd-fs@FreeBSD.ORG>, "Smallie, Scott" <Scott.Smallie@anheuser-busch.com> Subject: RE: lfs Message-ID: <31B3F0BF1C40D11192A700805FD48BF901776602@STLABCEXG011>
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> -----Original Message----- > From: Erick Engelke [SMTP:erick@dark.uwaterloo.ca] > Sent: Tuesday, July 07, 1998 9:39 AM > To: Alton, Matthew > Cc: 'hackers@freebsd.org'; 'freebsd-fs@freebsd.org'; Smallie, Scott > Subject: RE: lfs > > > > The actual error is in the lfs_writeseg() of lfs_segment.c > where lfs is copying individual bufs into contiguous memory > for a big long write. (called from lfs_segwrite, from lfs_sync) > > It looks like I'm dying at ++cbp->b_vp->v_numoutput... and a quick > look > suggests it is possible the vnode points to garbage. I'll have to > verify > that with kdb and experiment some more. [Alton, Matthew] We need to know precisely where panic() is called and whether it is called there exclusively. The lfs code has been sitting stagnant for a good long time and changes made 'around' it in the rest of the system may be breaking some assumptions. I don't know how stable this code was ever considered to be, but it's surprisingly pre-alpha now. I'm looking into ways to do automated bounds checking for pointer arithmetic for another (rent- paying) project and we may be able to use them here. > While on the topic, LFS has a lot of hacks, many specifically about > bufferring. Some other PC OS's simply manipulate the page tables to > map > buffers into contiguous RAM... (and then instruct 3rd parties to never > do > the same). I don't imagine that pagetable fiddling practice is ever > used > with FreeBSD, is it? > > [Alton, Matthew] FreeBSD is, thank God, really anything but a PC OS. All our APIs are published and everything! 8^D To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message
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