From mboxrd@z Thu Jan 1 00:00:00 1970 From: dv@vollmann.ch (Detlef Vollmann) Date: Sat, 14 May 2011 23:41:46 +0200 Subject: Kernel oops with undefined instruction when accessing memory on an AT91 custom system In-Reply-To: <4DCEADB5.9010905@usask.ca> References: <4DCEADB5.9010905@usask.ca> Message-ID: <4DCEF71A.9050405@vollmann.ch> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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