Date: Sat, 19 Mar 2011 12:34:54 +0100 From: Willem Jan Withagen <wjw@digiware.nl> To: Alan Cox <alc@rice.edu> Cc: Alan Cox <alc@freebsd.org>, freebsd-stable@freebsd.org, John Baldwin <jhb@freebsd.org> Subject: Re: panic on vm_page_cache_transfer: object 0xfffffff0035508000's type is not compatible with cache pages Message-ID: <4D8494DE.9050408@digiware.nl> In-Reply-To: <4D837C89.4000005@rice.edu> References: <4D760AEC.7050604@digiware.nl> <201103080915.29284.jhb@freebsd.org> <4D837C89.4000005@rice.edu>
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On 18-3-2011 16:38, Alan Cox wrote: > On 03/08/2011 08:15, John Baldwin wrote: >> On Tuesday, March 08, 2011 5:54:36 am Willem Jan Withagen wrote: >>> System: >>> >>> FreeBSD zfs.digiware.nl 8.2-STABLE FreeBSD 8.2-STABLE #1: Sat Feb 26 >>> 06:28:43 CET 2011 >>> root@zfs.digiware.nl:/usr/obj/usr/src/src8/src/sys/ZFS amd64 >>> >>> Don't have a serial console, so I wrote down the traceback. >>> But my guess is that that is not enough, however I needed the system so >>> I rebooted. >>> >>> tb: >>> vm_object_split at .... +0x125 >>> vm_space_fork at .... +0x3f7 >>> fork1 at .... +0x6a9 >>> fork at .... +0xee >>> syscall_entr at .... +1c >>> syscall at .... +4c >>> >>> rip = 0x8006bc39c >>> rsp = 0x7fffffffe9d8 >>> rbp = 0x800a04470 >>> >>> It looks a lot like what I find on >>> http://people.freebsd.org/~pho/stress/log/kostik079.html >>> >>> But my system is amd64, with 8Gb RAM and is fully ZFS based >>> with swap on 2 gpt freebsd-swap partitions. >>> >>> System crashed last night around 1:30, which is when a few large rsync >>> backups are coming in. >>> >>> Would I be able to call doadump to obtain something usefull afterward >>> (provided I have savecore set?) >> Hmm, judging from the info at the URL above, I'm not sure what to make >> of this >> assertion. In vm_object_split(), the 'new_object' is always >> OBJT_DEFAULT, so >> it will always fail that half of the assertion. In fact, this is the >> only >> place that vm_page_cache_transfer() is called, so 'new_object->type == >> OBJT_SWAP' is pretty much guaranteed to almost never be true. >> >> I guess it is assuming that swap_pager_copy() would have always converted >> 'new_object' to OBJT_SWAP if it had any cache pages? Perhaps that is >> a bogus >> assumption if 'orig_object' only has cache pages and no >> currently-swapped out >> pages (or if the swapped out pages are not in the range of the new >> object)? >> >> I've cc'd Alan to see if he has any ideas. >> > > Yes, it is assuming that the object is converted to OBJT_SWAP. As a > rule, for a page to be PG_CACHE, it should exist somewhere on secondary > storage. The panic has only occured twice thusfar, since I upgraded to FreeBSD 8.2-STABLE (ZFS) #1: Sat Feb 26 06:28:43 CET 2011. But I have the feeling that in due course, it'll return again. So if there are any suggestions on how to proceed, I would be happy to have a go at them. --WjW
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