Re: 2.6.27-rc5-mm1: rmmod ide-cd_mod: tried to init an initialized object, something is seriously wrong.

[Jens Axboe]

On Sat, Sep 06 2008, FUJITA Tomonori wrote:
> On Fri, 5 Sep 2008 18:25:04 +0200
> Mariusz Kozlowski <m.kozlowski@xxxxxxxxxx> wrote:
> 
> > Hello,
> > 
> > > > > 	Again 100% reproducible rmmod ide-cd_mod problem. Kernel is tainted because
> > > > > of earlier sysfs acpi problems similar (probably identical) to those reported
> > > > > by Li Zefan here http://marc.info/?l=linux-kernel&m=121921059026064&w=2
> > > > > 
> > > > > Steps to reproduce: unload ide-cd_mod
> > > > > 
> > > > > kobject (dd9e4a7c): tried to init an initialized object, something is seriously wrong.
> > > > > Pid: 4734, comm: modprobe Tainted: G        W 2.6.27-rc5-mm1 #1
> > > > >  [<c01ec982>] kobject_init+0xc4/0xc9
> > > > >  [<c02cb84a>] ? _spin_unlock+0x27/0x3f
> > > > >  [<c01aff2e>] ? sysfs_find_dirent+0x21/0x2b
> > > > >  [<c01aff7e>] ? __sysfs_add_one+0x46/0x6d
> > > > >  [<c01affb4>] ? sysfs_add_one+0xf/0x44
> > > > >  [<c01b0036>] ? sysfs_addrm_start+0x4d/0x90
> > > > >  [<c01b0f31>] ? sysfs_do_create_link+0x9a/0x14c
> > > > >  [<c01ec9c5>] kobject_init_and_add+0x14/0x30
> > > > >  [<c01b1009>] ? sysfs_create_link+0x12/0x19
> > > > >  [<c01e8bad>] blk_register_filter+0x3b/0x46
> > > > >  [<ded9e40a>] ide_cd_probe+0x253/0x5a8 [ide_cd_mod]
> > > > >  [<c01b0000>] ? sysfs_addrm_start+0x17/0x90
> > > > >  [<c01b0f31>] ? sysfs_do_create_link+0x9a/0x14c
> > > > >  [<c01b004e>] ? sysfs_addrm_start+0x65/0x90
> > > > >  [<c025145f>] generic_ide_probe+0x1f/0x21
> > > > >  [<c024c002>] driver_probe_device+0x77/0x15b
> > > > >  [<c02cb91b>] ? _spin_unlock_irqrestore+0x39/0x60
> > > > >  [<c024c146>] __driver_attach+0x60/0x62
> > > > >  [<c024b7bd>] bus_for_each_dev+0x44/0x62
> > > > >  [<c0251461>] ? generic_ide_remove+0x0/0x1e
> > > > >  [<c024bead>] driver_attach+0x19/0x1b
> > > > >  [<c024c0e6>] ? __driver_attach+0x0/0x62
> > > > >  [<c024bca8>] bus_add_driver+0x1ab/0x213
> > > > >  [<c0251461>] ? generic_ide_remove+0x0/0x1e
> > > > >  [<c024c291>] driver_register+0x4f/0x118
> > > > >  [<de7bf000>] ? ide_cdrom_init+0x0/0xf [ide_cd_mod]
> > > > >  [<de7bf00d>] ide_cdrom_init+0xd/0xf [ide_cd_mod]
> > > > >  [<c0101114>] do_one_initcall+0x24/0x12f
> > > > >  [<c02c9d8e>] ? mutex_unlock+0x8/0xa
> > > > >  [<c01455ca>] sys_init_module+0xa5/0x1c1
> > > > >  [<c0176a0a>] ? sys_read+0x3d/0x64
> > > > >  [<c01030f1>] sysenter_do_call+0x12/0x35
> > > > >  [<c012007b>] ? __set_special_pids+0x43/0x71
> > > > > 
> > > > > First time I modprobe/rmmod ide-cd_mod the system works but quickly gets unstable.
> > > > > Second modprobe/rmmod is 100% fatal. Memory gets corruped seriously I guess.
> > > > > pcspeaker beeps all the time, kernel throws dumps on the screen until
> > > > > its really dead, sadly blinking 'leds of panic' ;)
> > > > 
> > > > Can you please verify if that happens with the current mainline?
> > > 
> > > Oops. How come I didn't find it earlier? hmm...
> > 
> > It's relatively new, that's why :) And this is the culprit:
> > 
> > abf5439370491dd6fbb4fe1a7939680d2a9bc9d4 is first bad commit
> > commit abf5439370491dd6fbb4fe1a7939680d2a9bc9d4
> > Author: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
> > Date:   Sat Aug 16 14:10:05 2008 +0900
> > 
> >     block: move cmdfilter from gendisk to request_queue
> >     
> >     cmd_filter works only for the block layer SG_IO with SCSI block
> >     devices. It breaks scsi/sg.c, bsg, and the block layer SG_IO with SCSI
> >     character devices (such as st). We hit a kernel crash with them.
> >     
> >     The problem is that cmd_filter code accesses to gendisk (having struct
> >     blk_scsi_cmd_filter) via inode->i_bdev->bd_disk. It works for only
> >     SCSI block device files. With character device files, inode->i_bdev
> >     leads you to struct cdev. inode->i_bdev->bd_disk->blk_scsi_cmd_filter
> >     isn't safe.
> >     
> >     SCSI ULDs don't expose gendisk; they keep it private. bsg needs to be
> >     independent on any protocols. We shouldn't change ULDs to expose their
> >     gendisk.
> >     
> >     This patch moves struct blk_scsi_cmd_filter from gendisk to
> >     request_queue, a common object, which eveyone can access to.
> >     
> >     The user interface doesn't change; users can change the filters via
> >     /sys/block/. gendisk has a pointer to request_queue so the cmd_filter
> >     code accesses to struct blk_scsi_cmd_filter.
> >     
> >     Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
> >     Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx>
> > 
> > > This is current mainline:
> > > 
> > > kobject (ddb049fc): tried to init an initialized object, something is seriously wrong.
> > > Pid: 4650, comm: modprobe Not tainted 2.6.27-rc5-00132-gb380b0d #8
> > >  [<c01e3196>] kobject_init+0x6a/0x6c
> > >  [<c01e35cb>] kobject_init_and_add+0x14/0x30
> > >  [<c01e32f7>] ? kobject_get+0x12/0x17
> > >  [<c01df89c>] blk_register_filter+0x4b/0x5a
> > >  [<de839310>] ide_cd_probe+0x289/0x5ae [ide_cd_mod]
> > >  [<c01aad99>] ? sysfs_addrm_start+0x65/0x90
> > >  [<c01aba69>] ? sysfs_do_create_link+0x9a/0x11c
> > >  [<c024f7a0>] generic_ide_probe+0x1f/0x21
> > >  [<c024a672>] driver_probe_device+0x77/0x15b
> > >  [<c02c8bdb>] ? _spin_unlock_irqrestore+0x39/0x60
> > >  [<c024a7b6>] __driver_attach+0x60/0x62
> > >  [<c0249e2a>] bus_for_each_dev+0x44/0x62
> > >  [<c024f7a2>] ? generic_ide_remove+0x0/0x1e
> > >  [<c024a51d>] driver_attach+0x19/0x1b
> > >  [<c024a756>] ? __driver_attach+0x0/0x62
> > >  [<c024a318>] bus_add_driver+0x1ae/0x216
> > >  [<c024f7a2>] ? generic_ide_remove+0x0/0x1e
> > >  [<c024a901>] driver_register+0x4f/0x118
> > >  [<dee3500d>] ide_cdrom_init+0xd/0xf [ide_cd_mod]
> > >  [<c010111a>] do_one_initcall+0x2a/0x14c
> > >  [<c0108560>] ? native_sched_clock+0x58/0xa1
> > >  [<dee35000>] ? ide_cdrom_init+0x0/0xf [ide_cd_mod]
> > >  [<c013d042>] ? trace_hardirqs_on+0xb/0xd
> > >  [<c013cfaf>] ? trace_hardirqs_on_caller+0xac/0x134
> > >  [<c0147083>] sys_init_module+0x7e/0x19f
> > >  [<c013cfaf>] ? trace_hardirqs_on_caller+0xac/0x134
> > >  [<c01e8144>] ? trace_hardirqs_on_thunk+0xc/0x10
> > >  [<c0103035>] sysenter_do_call+0x12/0x35
> > >  [<c012007b>] ? put_fs_struct+0x5/0x2e
> 
> ide-cd uses multiple gendisks share one request_queue?
> 
> Here's a patch for mainline.

Hmm, I don't think that it does. There's a queue per drive in the old
IDE driver, so there should be a 1:1 relation between queues and gendisk
there.

> 
> =
> From: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
> Subject: [PATCH] ide: remove cmd filter support in ide-cd
> 
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
> ---
>  drivers/ide/ide-cd.c |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
> index f148999..49a8c58 100644
> --- a/drivers/ide/ide-cd.c
> +++ b/drivers/ide/ide-cd.c
> @@ -1933,7 +1933,6 @@ static void ide_cd_remove(ide_drive_t *drive)
>  
>  	ide_proc_unregister_driver(drive, info->driver);
>  
> -	blk_unregister_filter(info->disk);
>  	del_gendisk(info->disk);
>  
>  	ide_cd_put(info);
> @@ -2159,7 +2158,6 @@ static int ide_cd_probe(ide_drive_t *drive)
>  	g->fops = &idecd_ops;
>  	g->flags |= GENHD_FL_REMOVABLE;
>  	add_disk(g);
> -	blk_register_filter(g);
>  	return 0;
>  
>  out_free_cd:
> -- 
> 1.5.4.2
> 

-- 
Jens Axboe

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