Messages in this thread Patch in this message | | | Date | Sat, 30 Aug 2008 19:04:08 +0200 (MEST) | From | Mikael Pettersson <> | Subject | [REGRESSION 2.6.27-rc4-git7] mtd broken by cmdfilter move |
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Starting with kernel 2.6.27-rc4-git7 my n2100 arm box throws a bunch of kobject errors at boot:
Creating 6 MTD partitions on "physmap-flash.0": 0x00000000-0x00040000 : "RedBoot" 0x00040000-0x00d40000 : "ramdisk" kobject (df8fd510): tried to init an initialized object, something is seriously wrong. [<c0024c68>] (dump_stack+0x0/0x14) from [<c01136f4>] (kobject_init+0x40/0x78) [<c01136b4>] (kobject_init+0x0/0x78) from [<c0113c28>] (kobject_init_and_add+0x20/0x44) r5:df8fd510 r4:df9ee8b0 [<c0113c0c>] (kobject_init_and_add+0x4/0x44) from [<c010a92c>] (blk_register_filter+0x4c/0x60) r5:df8f6d20 r4:df8fd108 [<c010a8e0>] (blk_register_filter+0x0/0x60) from [<c010983c>] (add_disk+0x60/0xb8) r4:df9ee800 [<c01097dc>] (add_disk+0x0/0xb8) from [<c0170bb4>] (add_mtd_blktrans_dev+0x248/0x284) r5:df8f6d20 r4:00000001 [<c017096c>] (add_mtd_blktrans_dev+0x0/0x284) from [<c01711a8>] (mtdblock_add_mtd+0x5c/0x68) r8:00040000 r7:df8604cc r6:c02c5c98 r5:c02c5cc8 r4:df8602a0 [<c017114c>] (mtdblock_add_mtd+0x0/0x68) from [<c017075c>] (blktrans_notify_add+0x38/0x64) r5:df8602a0 r4:c02c5cc8 [<c0170724>] (blktrans_notify_add+0x0/0x64) from [<c016daec>] (add_mtd_device+0xb4/0x110) r6:c02c5c34 r5:df8602a0 r4:c02c5c88 [<c016da38>] (add_mtd_device+0x0/0x110) from [<c016ee70>] (add_mtd_partitions+0x490/0x54c) r6:df844080 r5:00000c00 r4:df8602a0 [<c016e9e0>] (add_mtd_partitions+0x0/0x54c) from [<c01789b8>] (physmap_flash_probe+0x27c/0x2e8) [<c017873c>] (physmap_flash_probe+0x0/0x2e8) from [<c01468b8>] (platform_drv_probe+0x20/0x24) [<c0146898>] (platform_drv_probe+0x0/0x24) from [<c0145b20>] (driver_probe_device+0xd8/0x18c) [<c0145a48>] (driver_probe_device+0x0/0x18c) from [<c0145c20>] (__driver_attach+0x4c/0x70) r7:c02c5e1c r6:c02c5e1c r5:c02b8338 r4:c02b828c [<c0145bd4>] (__driver_attach+0x0/0x70) from [<c0145180>] (bus_for_each_dev+0x54/0x88) r6:c0145bd4 r5:df821ec0 r4:00000000 [<c014512c>] (bus_for_each_dev+0x0/0x88) from [<c0145960>] (driver_attach+0x20/0x28) r7:df88c620 r6:00000000 r5:c02c5e1c r4:00000000 [<c0145940>] (driver_attach+0x0/0x28) from [<c0145618>] (bus_add_driver+0xa8/0x214) [<c0145570>] (bus_add_driver+0x0/0x214) from [<c0145e14>] (driver_register+0x98/0x120) r8:00000000 r7:00000000 r6:00000000 r5:c02c5e1c r4:c02cd924 [<c0145d7c>] (driver_register+0x0/0x120) from [<c0146a78>] (platform_driver_register+0x78/0x94) [<c0146a00>] (platform_driver_register+0x0/0x94) from [<c0016ee4>] (physmap_init+0x14/0x1c) [<c0016ed0>] (physmap_init+0x0/0x1c) from [<c00202b8>] (__exception_text_end+0x50/0x184) [<c0020268>] (__exception_text_end+0x0/0x184) from [<c000874c>] (kernel_init+0x70/0xd8) [<c00086dc>] (kernel_init+0x0/0xd8) from [<c003750c>] (do_exit+0x0/0x708) r5:00000000 r4:00000000 0x00d40000-0x00ea0000 : "kernel" kobject (df8fd510): tried to init an initialized object, something is seriously wrong.
and so on for every partition except the first one.
I bisected this to commit abf5439370491dd6fbb4fe1a7939680d2a9bc9d4, "block: move cmdfilter from gendisk to request_queue".
There is a many-to-one mapping from gendisks to queues, so when this commit moved the cmd_filter object from the gendisk to the gendisk's queue it allowed (by design or by accident, I don't know) gendisks to share cmd_filters. However, the commit didn't update blk_register_filter() to handle shared cmd_filters: it still unconditionally calls kobject_init_and_add() for the gendisk's cmd_filter kobject. When queue and thus cmd_filter sharing is present, reinitialisation of already initialised kobjects occur, resulting in loud complaints from lib/kobject.c.
As a quick workaround I added a check to blk_register_filter() to avoid reinitialising already initialised cmd_filters, and to log the addresses of the disks, queues, and cmd_filters passed to it:
--- linux-2.6.27-rc4-git6/block/cmd-filter.c.~1~ 2008-08-30 17:08:58.000000000 +0200 +++ linux-2.6.27-rc4-git6/block/cmd-filter.c 2008-08-30 17:36:36.000000000 +0200 @@ -215,6 +215,13 @@ int blk_register_filter(struct gendisk * if (!parent) return -ENODEV; + printk("%s: disk %p queue %p filter %p &filter->kobj %p\n", + __func__, disk, disk->queue, filter, &filter->kobj); + if (filter->kobj.state_initialized) { + printk("%s: kobj %p already inited, bailing out\n", + __func__, &filter->kobj); + return 0; + } ret = kobject_init_and_add(&filter->kobj, &rcf_ktype, parent, "%s", "cmd_filter"); This eliminated the kobject complaints for me. The log messages also showed that the mtd gendisks indeed share queue and thus cmd_filter and its kobject: 6 RedBoot partitions found on MTD device physmap-flash.0 Creating 6 MTD partitions on "physmap-flash.0": 0x00000000-0x00040000 : "RedBoot" blk_register_filter: disk df8f4000 queue df8fd108 filter df8fd4d0 &filter->kobj df8fd510 0x00040000-0x00d40000 : "ramdisk" blk_register_filter: disk df9f0800 queue df8fd108 filter df8fd4d0 &filter->kobj df8fd510 blk_register_filter: kobj df8fd510 already inited, bailing out 0x00d40000-0x00ea0000 : "kernel" blk_register_filter: disk df9f0000 queue df8fd108 filter df8fd4d0 &filter->kobj df8fd510 blk_register_filter: kobj df8fd510 already inited, bailing out 0x00ea0000-0x00fc0000 : "user" blk_register_filter: disk df9ed800 queue df8fd108 filter df8fd4d0 &filter->kobj df8fd510 blk_register_filter: kobj df8fd510 already inited, bailing out 0x00fc0000-0x00fc1000 : "RedBoot config" blk_register_filter: disk df9ed000 queue df8fd108 filter df8fd4d0 &filter->kobj df8fd510 blk_register_filter: kobj df8fd510 already inited, bailing out 0x00fe0000-0x01000000 : "FIS directory" blk_register_filter: disk df9ea800 queue df8fd108 filter df8fd4d0 &filter->kobj df8fd510 blk_register_filter: kobj df8fd510 already inited, bailing out I'll leave it to you guys to decide what the proper fix for this mess should be.
/Mikael
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