Date: Sun, 22 Jul 2007 18:53:32 +0200 (CEST) From: Juergen Lock <nox@jelal.kn-bremen.de> To: mime@traveller.cz Cc: freebsd-stable@freebsd.org Subject: Re: Panic with umass (with USB tape and Amanda) Message-ID: <200707221653.l6MGrWMu003868@saturn.kn-bremen.de> In-Reply-To: <1184792674.1670.7.camel@genius.i.cz>
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In article <1184792674.1670.7.camel@genius.i.cz> you write: >Hello everybody, Hi! > >I have just had a panic on 6.2 amd64 box with ehci connected USB DDS4 >tape drive while it was for the first time being accessed with Amanda. I >have previously successfully tested it with tar. > >I have a kernel crash dump with the following information: > >panic: trying to sleep while sleeping is prohibited >cpuid = 0 >KDB: stack backtrace: >panic() at panic+0x250 >sleepq_add() at sleepq_add+0x225 >msleep() at msleep+0x132 >bwait() at bwait+0x55 >swap_pager_putpages() at swap_pager_putpages+0x45c >vm_pageout_flush() at vm_pageout_flush+0x13b >vm_contig_launder_page() at vm_contig_launder_page+0xdc >vm_page_alloc_contig() at vm_page_alloc_contig+0x321 >contigmalloc() at contigmalloc+0x5f7 >bus_dmamem_alloc() at bus_dmamem_alloc+0x80 >usb_block_allocmem() at usb_block_allocmem+0x118 >... This looks like the known problem of bus_dmamem_alloc sleeping when it shouldn't (its being called with BUS_DMA_NOWAIT), which has hit me with usb before. Workarounds: 1. add more RAM (this seems to be triggered by page shortage/fragmentation) 2. reboot before you use the device 3. try the HPS usb stack, it may have worked around this issue: http://www.turbocat.net/~hselasky/usb4bsd/ (I hope this is still the right url, I haven't used the stack in a while.) HTH, Juergen
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