Messages in this thread | | | Date | Wed, 18 Apr 2012 14:55:05 +0200 (CEST) | From | Joel Reardon <> | Subject | Re: mtdchar kernel oops |
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Perhaps Artem can shed some light on this, I'm working on a branch he's prepared. But if its not happening at your end then perhaps something's up on mine; the oops log is rather bizzare. I'll remake it from scratch and see what happens.
Cheers, Joel
On Mon, 16 Apr 2012, Al Viro wrote:
> On Mon, Apr 16, 2012 at 02:37:06PM +0200, Joel Reardon wrote: > > The troubled asm pair corresponds to this line: > > this_cpu_add(mnt->mnt_pcp->mnt_count, n) in the inline mnt_add_count(). > > So I suppose that perhaps either mnt is bad, or mnt_pcp is bad. > > > > I'm using nandsim to simulate the mtd device. Steps are simple, load the > > modules: > > nand_ecc nand nand_ids mtd mtd_blkdevs mtdblock mtdchar > > nandsim first_id_byte=0x20 second_id_byte=0xa5 third_id_byte=0x00 fourth_id_byte=0x15 parts=0xa40 rptwear=1000 > > > > then `ubiformat /dev/mtd0` does the oops. > > Not here: > > root@dizzy:~# modprobe nandsim first_id_byte=0x20 second_id_byte=0xa5 third_id_byte=0x00 fourth_id_byte=0x15 parts=0xa40 rptwear=1000 > ubiformat: mtd0 (nand), size 343932928 bytes (328.0 MiB), 2624 eraseblocks of 131072 bytes (128.0 KiB), min. I/O size 2048 bytes > libscan: scanning eraseblock 2623 -- 100 % complete > ubiformat: 2624 eraseblocks are supposedly empty > ubiformat: formatting eraseblock 2623 -- 100 % complete > root@dizzy:~# uname -a > Linux dizzy 3.4.0-rc2+ #4 SMP Mon Apr 16 15:04:25 EDT 2012 x86_64 GNU/Linux > > and no oopsen in sight... > > > > > Could you add printk into mtdchar_open(), dumping mnt and count values > > > right after simple_pin_fs() call? > > > > > > > It oopses before it returns from the simple_pin_fs call, so that won't be > > possible... > > Wha...? You mean, that happens on the _first_ simple_pin_fs() call? > But that makes no damn sense whatsoever - we just do vfs_kern_mount(), > get a vfsmount from it (and not an ERR_PTR(), at that), then store > it into mnt and do mntget(mnt) followed by mntput(mnt). If that really > happens when simple_pin_fs() gets called with mnt == NULL and count == 0, > we have much bigger problem on hands... > > Please, slap such printks before and after simple_pin_fs() in mtdchar_open() > and before and after simple_release_fs() in mtdchar_close(). And verify that > you have commit c65390f4dd49755863f6d772ec538ee4757c08d7 in your tree. >
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