Date: Sun, 09 Jan 2005 01:37:17 +0000 From: Ian Dowse <iedowse@maths.tcd.ie> To: Peter Jeremy <PeterJeremy@optushome.com.au> Cc: freebsd-stable@freebsd.org Subject: Re: 4.10 kernel panic: Fatal trap 12: page fault while in kernel mode Message-ID: <200501090137.aa00596@salmon.maths.tcd.ie> In-Reply-To: Your message of "Sun, 09 Jan 2005 11:58:39 %2B1100." <20050109005838.GX79646@cirb503493.alcatel.com.au>
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In message <20050109005838.GX79646@cirb503493.alcatel.com.au>, Peter Jeremy wri tes: >On Wed, Dec 15, 2004 at 12:42:25PM -0800, Scott Sewall wrote: >> I'm running FreeBSD 4.10-RELEASE-p3 that occasionally panics. The panic >> occurs seems to happen when I'm running rsync of large directories >> possibly in combination with reading or writing to a compact flash >> attached to USB. > >Having just looked into an identical panic, the problem is an >interface bug between bus_dmamem_alloc() and contigmalloc(). It's >nothing to do with USB and (AFAIK) exists in 4.x, 5.x and 6.x. The USB code is not entirely free of blame here however. It allocates numerous big chunks of contiguous memory for tranfer buffers instead of using the (admittedly limited) scatter-gather capabilities of the USB host controllers. Try applying the change from revision 1.6 of usb_mem.c. This fixed one particularly inefficient memory use behaviour in the USB code. That change is already in 5.x and 6.x, but wasn't merged to 4.x. http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/dev/usb/usb_mem.c Ian
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