Witam, > On Mon, Sep 08 2008, Jens Axboe wrote: > > 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. > > I think the problem here is due to the usage of kobject_init_and_add(). > When we hit the add the second time, the ->state_initalised in the kojb > is still 1. The below should fix it. > > The ->state_initalised stuff is a disaster imho, it should be shot and > killed. > > diff --git a/block/blk-core.c b/block/blk-core.c > index 6cb3c6d..820132b 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -495,6 +495,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) > INIT_LIST_HEAD(&q->timeout_list); > > kobject_init(&q->kobj, &blk_queue_ktype); > + kobject_init(&q->cmd_filter.kobj, &rcf_ktype); > > mutex_init(&q->sysfs_lock); > spin_lock_init(&q->__queue_lock); > diff --git a/block/blk.h b/block/blk.h > index eb13740..47d6b22 100644 > --- a/block/blk.h > +++ b/block/blk.h > @@ -9,6 +9,7 @@ > > extern struct kmem_cache *blk_requestq_cachep; > extern struct kobj_type blk_queue_ktype; > +extern struct kobj_type rcf_ktype; > > void init_request_from_bio(struct request *req, struct bio *bio); > void blk_rq_bio_prep(struct request_queue *q, struct request *rq, > diff --git a/block/cmd-filter.c b/block/cmd-filter.c > index da7f7a4..9556e85 100644 > --- a/block/cmd-filter.c > +++ b/block/cmd-filter.c > @@ -201,7 +201,7 @@ static struct sysfs_ops rcf_sysfs_ops = { > .store = rcf_attr_store, > }; > > -static struct kobj_type rcf_ktype = { > +struct kobj_type rcf_ktype = { > .sysfs_ops = &rcf_sysfs_ops, > .default_attrs = default_attrs, > }; > @@ -211,8 +211,7 @@ int blk_register_filter(struct gendisk *disk) > int ret; > struct blk_cmd_filter *filter = &disk->queue->cmd_filter; > > - ret = kobject_init_and_add(&filter->kobj, &rcf_ktype, > - &disk_to_dev(disk)->kobj, > + ret = kobject_add(&filter->kobj, &disk_to_dev(disk)->kobj, > "%s", "cmd_filter"); > if (ret < 0) > return ret; > I applied your fix to 2.6.27-rc5-mm1 (it doesn't apply to mainline) and the result is that when I first rmmod ide-cd_mod it's ok, but it seems that the module is not unregistered because when you rmmod ide-cd_mod again immediately you will see this: BUG: atomic counter underflow at: Pid: 4920, comm: rmmod Tainted: G W 2.6.27-rc5-mm1 #4 [<c01ec579>] ? kobject_release+0x0/0x59 [<c01ed300>] kref_put+0x4c/0x7c [<c01ec4cc>] kobject_put+0x20/0x4e [<c01aed10>] ? sysfs_hash_and_remove+0x50/0x57 [<c01e8d4b>] blk_unregister_filter+0x13/0x15 [<dedd822b>] ide_cd_remove+0xf/0x21 [ide_cd_mod] [<c025147b>] generic_ide_remove+0x1a/0x1e [<c024bdaf>] __device_release_driver+0x59/0x7f [<c024be6c>] driver_detach+0x97/0x99 [<c024b26e>] bus_remove_driver+0x6f/0x8b [<c024c231>] driver_unregister+0x2f/0x33 [<deddb341>] ide_cdrom_exit+0xd/0xf [ide_cd_mod] [<c0143da5>] sys_delete_module+0x10d/0x1e2 [<c0162cbc>] ? do_munmap+0x1d7/0x234 [<c0163d13>] ? sys_munmap+0x30/0x36 [<c01030f1>] sysenter_do_call+0x12/0x35 ======================= hdc: ATAPI 24X DVD-ROM CD-R/RW drive, 2048kB Cache Btw I found something interesting. On earlier kernels - 2.6.25 I can not remove ide-cd_mod at all - it's still there when I lsmod modules: # modprobe ide-cd_mod # rmmod ide-cd_mod # rmmod ide-cd_mod # rmmod ide-cd_mod # rmmod ide-cd_mod # rmmod ide-cd_mod # rmmod ide-cd_mod # rmmod ide-cd_mod # lsmod | grep ide_cd ide_cd_mod 29600 0 cdrom 32160 1 ide_cd_mod On the other hand on newer kernels (post 2.6.26 - these which did not blow up) right after boot I have to run rmmod ide-cd_mod exactly three times to have ide-cd_mod unloaded. If I modprobe and rmmod again it works as expected. Why is this? laptop mako # modprobe ide-cd_mod laptop mako # rmmod ide-cd_mod laptop mako # rmmod ide-cd_mod laptop mako # rmmod ide-cd_mod laptop mako # rmmod ide-cd_mod ERROR: Module ide_cd_mod does not exist in /proc/modules laptop mako # modprobe ide-cd_mod laptop mako # rmmod ide-cd_mod laptop mako # rmmod ide-cd_mod ERROR: Module ide_cd_mod does not exist in /proc/modules Mariusz -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
