Date: Sat, 09 Nov 2002 14:38:28 -0600 From: "Alan L. Cox" <alc@imimic.com> To: Jeff Roberson <jroberson@chesapeake.net> Cc: Matthew Jacob <mjacob@feral.com>, Andrew Gallatin <gallatin@cs.duke.edu>, alpha@FreeBSD.ORG, alc@FreeBSD.ORG, John Baldwin <jhb@FreeBSD.ORG> Subject: Re: alpha: top of tree kernel blooie Message-ID: <3DCD7244.DEEA7387@imimic.com> References: <20021109150359.B97372-100000@mail.chesapeake.net>
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Jeff Roberson wrote: > > On Fri, 8 Nov 2002, Matthew Jacob wrote: > > > > > > > > > Can you 'ps aux -o wchan' ? > > > > I tried a buildworld -j4 again- this time it was too far hung to let > > anyone log in... > > > > > > I ran into the vm_map_delete() duplicate free again. This has been the > same code path too many times for it to be a non logic bug. > > Jeff I'm still wondering if this isn't a false positive: 1. My reading of the UMA debug code is that two or more processors can simultaneously read and modify us_freelist[]. The only lock held during an access is the CPU private lock. 2. Don't we compile by default for the older Alphas that lack byte manipulation instructions? Thus, a byte store is implemented by a read-modify-write sequence of instructions. Thus, two simultaneous uma_dbg_alloc()s on adjacent locations in us_freelist could cause corruption. Regards, Alan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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