MTD/block regression (was Re: Slub debugging NAND error in 2.6.25.10.atmel.2)

[FUJITA Tomonori]

On Fri, 29 Aug 2008 16:28:24 +0200
Haavard Skinnemoen <haavard.skinnemoen at atmel.com> wrote:

> Haavard Skinnemoen <haavard.skinnemoen at atmel.com> wrote:
> > Hmm...I just saw this when booting 2.6.27-rc5 on the NGW100:
> > 
> > physmap platform flash device: 00800000 at 00000000
> > physmap-flash.0: Found 1 x16 devices at 0x0 in 16-bit bank
> >  Amd/Fujitsu Extended Query Table at 0x0041
> > number of CFI chips: 1
> > cfi_cmdset_0002: Disabling erase-suspend-program due to code brokenness.
> > RedBoot partition parsing not available
> > Using physmap partition information
> > Creating 3 MTD partitions on "physmap-flash.0":
> > 0x00000000-0x00020000 : "u-boot"
> > 0x00020000-0x007f0000 : "root"
> > kobject (91ce8410): tried to init an initialized object, something is seriously wrong.
> > Call trace:
> >  [<90017184>] dump_stack+0x18/0x20
> >  [<900c1894>] kobject_init+0x28/0x5c
> >  [<900c1bf6>] kobject_init_and_add+0xe/0x24
> >  [<900beff0>] blk_register_filter+0x28/0x40
> >  [<900be224>] add_disk+0x38/0x68
> >  [<900e70f0>] add_mtd_blktrans_dev+0x174/0x184
> >  [<900e748e>] mtdblock_add_mtd+0x36/0x3c
> >  [<900e6e38>] blktrans_notify_add+0x1a/0x3a
> >  [<900e533c>] add_mtd_device+0x60/0xa0
> >  [<900e5f7e>] add_mtd_partitions+0x37a/0x3a0
> >  [<900ec4d0>] physmap_flash_probe+0x1ec/0x21c
> >  [<900e0f24>] platform_drv_probe+0x10/0x12
> >  [<900e06d0>] driver_probe_device+0x84/0xf0
> >  [<900e076a>] __driver_attach+0x2e/0x44
> >  [<900e0096>] bus_for_each_dev+0x2e/0x4c
> >  [<900e05b6>] driver_attach+0x12/0x14
> >  [<900e036c>] bus_add_driver+0x6c/0x178
> >  [<900e08a4>] driver_register+0x58/0xb0
> >  [<900e1126>] platform_driver_register+0x56/0x5c
> >  [<9000aaf6>] physmap_init+0xa/0x10
> >  [<9001422a>] do_one_initcall+0x2a/0x10c
> >  [<900005b8>] kernel_init+0x48/0x90
> >  [<9001fcc0>] do_exit+0x0/0x4cc
> > 
> > 0x007f0000-0x00800000 : "env"
> > kobject (91ce8410): tried to init an initialized object, something is seriously wrong.
> > Call trace:
> >  [<90017184>] dump_stack+0x18/0x20
> >  [<900c1894>] kobject_init+0x28/0x5c
> >  [<900c1bf6>] kobject_init_and_add+0xe/0x24
> >  [<900beff0>] blk_register_filter+0x28/0x40
> >  [<900be224>] add_disk+0x38/0x68
> >  [<900e70f0>] add_mtd_blktrans_dev+0x174/0x184
> >  [<900e748e>] mtdblock_add_mtd+0x36/0x3c
> >  [<900e6e38>] blktrans_notify_add+0x1a/0x3a
> >  [<900e533c>] add_mtd_device+0x60/0xa0
> >  [<900e5f7e>] add_mtd_partitions+0x37a/0x3a0
> >  [<900ec4d0>] physmap_flash_probe+0x1ec/0x21c
> >  [<900e0f24>] platform_drv_probe+0x10/0x12
> >  [<900e06d0>] driver_probe_device+0x84/0xf0
> >  [<900e076a>] __driver_attach+0x2e/0x44
> >  [<900e0096>] bus_for_each_dev+0x2e/0x4c
> >  [<900e05b6>] driver_attach+0x12/0x14
> >  [<900e036c>] bus_add_driver+0x6c/0x178
> >  [<900e08a4>] driver_register+0x58/0xb0
> >  [<900e1126>] platform_driver_register+0x56/0x5c
> >  [<9000aaf6>] physmap_init+0xa/0x10
> >  [<9001422a>] do_one_initcall+0x2a/0x10c
> >  [<900005b8>] kernel_init+0x48/0x90
> >  [<9001fcc0>] do_exit+0x0/0x4cc
> > 
> > I wonder if it's related?
> 
> Ok, it turns out it's not related. It's a newly introduced regression
> which I've bisected down to:
> 
> commit abf5439370491dd6fbb4fe1a7939680d2a9bc9d4
> Author: FUJITA Tomonori <fujita.tomonori at lab.ntt.co.jp>
> Date:   Sat Aug 16 14:10:05 2008 +0900
> 
>     block: move cmdfilter from gendisk to request_queue

Really sorry about that. A fix was queued in Jens' tree:

http://marc.info/?l=linux-kernel&m=122000748432301&w=2


> Unfortunately, I can't revert it cleanly, so it could be a false
> positive. But it does sort of make sense, since it makes the filter
> per-queue instead of per-gendisk, so if MTD uses the same queue for
> several block devices, the filter kobject might end up being
> initialized multiple times. Or something.

Right, the problem is that MTD uses the same queue for multiple
gendisks. It would be great if a MTD developer could fix it.


Thanks,