From mboxrd@z Thu Jan 1 00:00:00 1970 From: n.kinar@usask.ca (Nicholas Kinar) Date: Sat, 14 May 2011 21:52:21 -0600 Subject: Kernel oops with undefined instruction when accessing memory on an AT91 custom system In-Reply-To: <4DCEF71A.9050405@vollmann.ch> References: <4DCEADB5.9010905@usask.ca> <4DCEF71A.9050405@vollmann.ch> Message-ID: <4DCF4DF5.8020004@usask.ca> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Detlef Vollmann wrote: > On 05/14/11 18:28, Nicholas Kinar wrote: >> I've had a number of random kernel oops when trying to use the AT91 mmc >> driver with an SD card, > I'm not sure if this is related, but we also get oopses with SDcard, > with both, at91_mci.c and atmel-mci.c. > But we only get it with debugging turned on (CONFIG_DEBUG_BUGVERBOSE=y > and CONFIG_DEBUG_VM=y). > This is the interesting part of the oops: > kernel BUG at include/linux/mm.h:636 > [] (__bug+0x18/0x24) from [] > (flush_dcache_page+0x28/0x144) > [] (flush_dcache_page+0x28/0x144) from [] > (atmci_interrupt+0x1f4/0x6ec) > [] (atmci_interrupt+0x1f4/0x6ec) from [] > (handle_IRQ_event+0x3c/0x10c) > > This is for a 2.6.32 kernel, but I also tested 2.6.39-rc4. > The interesting thing is that this only happens with SDcard, with > an original MMC card everything is fine. > I haven't had the time yet to hunt this down, but I propose you > turn on DEBUG_VM and BUG and see whether you get more consistent oopses. > > Detlef Thanks for your response, Detlef. It appears that the AT91 mmc driver is a little bit more stable now with debugging turned off. The kernel oops still continues as documented in my response to Nicolas Ferre, but I think that the debugging should indeed be turned off in a production system. Once again, thank you very much for your response! Nicholas