need help with slub.c duplicate filename '/kernel/slab/:t-0000048' problem

need help with slub.c duplicate filename '/kernel/slab/:t-0000048' problem

[andy_purcell]

Hello,

I am using a Linux kernel = 4.14.13. Debug. 

The problem: 
=============
If I attach a USB flash drive and then turn my device power on, then during the boot, I see this:  
             sysfs: cannot create duplicate filename '/kernel/slab/:t-0000048'

Result: the application does not boot successfully. 
This happens about 50% of the time when booting with the USB flash drive attached. 
Flash drive is FAT32, 3.7 GBytes. 

This happens with several different USB flash drives. 

---------------- more complete output below --------------------
ubi0: attaching mtd13
usb 2-1: new high-speed USB device number 2 using xxx-ehci
ubi0: scanning is finished
usb-storage 2-1:1.0: USB Mass Storage device detected
ubi0: attached mtd13 (name "rootfs", size 104 MiB)
ubi0: PEB size: 131072 bytes (128 KiB), LEB size: 129024 bytes
ubi0: min./max. I/O unit sizes: 2048/2048, sub-page size 512
ubi0: VID header offset: 512 (aligned 512), data offset: 2048
ubi0: good PEBs: 836, bad PEBs: 0, corrupted PEBs: 0
ubi0: user volume: 3, internal volumes: 1, max. volumes count: 128
ubi0: max/mean erase counter: 1/0, WL threshold: 4096, image sequence number: 1705465617
ubi0: available PEBs: 180, total reserved PEBs: 656, PEBs reserved for bad PEB handling: 40
ubi1: attaching mtd11
ubi0: background thread "ubi_bgt0d" started, PID 714
ubi1: scanning is finished
ubi1: attached mtd11 (name "system-storage", size 8 MiB)
ubi1: PEB size: 131072 bytes (128 KiB), LEB size: 129024 bytes
ubi1: min./max. I/O unit sizes: 2048/2048, sub-page size 512
ubi1: VID header offset: 512 (aligned 512), data offset: 2048
ubi1: good PEBs: 64, bad PEBs: 0, corrupted PEBs: 0
ubi1: user volume: 1, internal volumes: 1, max. volumes count: 128
ubi1: max/mean erase counter: 2/0, WL threshold: 4096, image sequence number: 945702109
ubi1: available PEBs: 0, total reserved PEBs: 64, PEBs reserved for bad PEB handling: 40
ubi2: attaching mtd12
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at /var/lib/jenkins/workspace/Rocky.Scheduled.Build/bitbake/build/tmp/development/tlo/work-shared/xxx/development/kernel-source/fs/sysfs/dir.c:31 sysfs_warn_dup+0x54/0x74
sysfs: cannot create duplicate filename '/kernel/slab/:t-0000048'
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Not tainted 4.14.13-andyp-development #1 Hardware name: xxx (Flattened Device Tree) [<c000f7c4>] (unwind_backtrace) from [<c000d758>] (show_stack+0x10/0x14) [<c000d758>] (show_stack) from [<c00174d8>] (__warn+0xd4/0xfc) [<c00174d8>] (__warn) from [<c0017538>] (warn_slowpath_fmt+0x38/0x48) [<c0017538>] (warn_slowpath_fmt) from [<c012e5b8>] (sysfs_warn_dup+0x54/0x74) [<c012e5b8>] (sysfs_warn_dup) from [<c012e69c>] (sysfs_create_dir_ns+0x80/0x94) [<c012e69c>] (sysfs_create_dir_ns) from [<c04ea88c>] (kobject_add_internal+0x9c/0x2d8) [<c04ea88c>] (kobject_add_internal) from [<c04eace8>] (kobject_init_and_add+0x44/0x6c) [<c04eace8>] (kobject_init_and_add) from [<c00c1a6c>] (sysfs_slab_add+0x124/0x230) [<c00c1a6c>] (sysfs_slab_add) from [<c00c2bb8>] (__kmem_cache_create+0x108/0x33c) [<c00c2bb8>] (__kmem_cache_create) from [<c009d644>] (kmem_cache_create+0x114/0x22c) [<c009d644>] (kmem_cache_create) from [<c031ca3c>] (ubi_attach+0x94/0x1608) [<c031ca3c>] (ubi_attach) from [<c031130c>] (ubi_attach_mtd_dev+0x3e4/0xb74) [<c031130c>] (ubi_attach_mtd_dev) from [<c06732b8>] (ubi_init+0x164/0x21c) [<c06732b8>] (ubi_init) from [<c0009978>] (do_one_initcall+0x3c/0x174) [<c0009978>] (do_one_initcall) from [<c065dd60>] (kernel_init_freeable+0x108/0x1bc)
[<c065dd60>] (kernel_init_freeable) from [<c04fa710>] (kernel_init+0x8/0xf4) [<c04fa710>] (kernel_init) from [<c000a740>] (ret_from_fork+0x14/0x34) ---[ end trace ba5c8beef5034fec ]--- ------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at /var/lib/jenkins/workspace/Rocky.Scheduled.Build/bitbake/build/tmp/development/tlo/work-shared/xxx/development/kernel-source/lib/kobject.c:240 kobject_add_internal+0x230/0x2d8 kobject_add_internal failed for :t-0000048 with -EEXIST, don't try to register things with the same name in the same directory.
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Tainted: G        W       4.14.13-andyp-development #1
Hardware name: xxx (Flattened Device Tree) [<c000f7c4>] (unwind_backtrace) from [<c000d758>] (show_stack+0x10/0x14) [<c000d758>] (show_stack) from [<c00174d8>] (__warn+0xd4/0xfc) [<c00174d8>] (__warn) from [<c0017538>] (warn_slowpath_fmt+0x38/0x48) [<c0017538>] (warn_slowpath_fmt) from [<c04eaa20>] (kobject_add_internal+0x230/0x2d8)
[<c04eaa20>] (kobject_add_internal) from [<c04eace8>] (kobject_init_and_add+0x44/0x6c) [<c04eace8>] (kobject_init_and_add) from [<c00c1a6c>] (sysfs_slab_add+0x124/0x230) [<c00c1a6c>] (sysfs_slab_add) from [<c00c2bb8>] (__kmem_cache_create+0x108/0x33c) [<c00c2bb8>] (__kmem_cache_create) from [<c009d644>] (kmem_cache_create+0x114/0x22c) [<c009d644>] (kmem_cache_create) from [<c031ca3c>] (ubi_attach+0x94/0x1608) [<c031ca3c>] (ubi_attach) from [<c031130c>] (ubi_attach_mtd_dev+0x3e4/0xb74) [<c031130c>] (ubi_attach_mtd_dev) from [<c06732b8>] (ubi_init+0x164/0x21c) [<c06732b8>] (ubi_init) from [<c0009978>] (do_one_initcall+0x3c/0x174) [<c0009978>] (do_one_initcall) from [<c065dd60>] (kernel_init_freeable+0x108/0x1bc)
[<c065dd60>] (kernel_init_freeable) from [<c04fa710>] (kernel_init+0x8/0xf4) [<c04fa710>] (kernel_init) from [<c000a740>] (ret_from_fork+0x14/0x34) ---[ end trace ba5c8beef5034fed ]---
kmem_cache_create(ubi_aeb_slab_cache) failed with error -17
CPU: 0 PID: 1 Comm: swapper Tainted: G        W       4.14.13-andyp-development #1
 [<c000f7c4>] (unwind_backtrace) from [<c000d758>] (show_stack+0x10/0x14) [<c000d758>] (show_stack) from [<c009d588>] (kmem_cache_create+0x58/0x22c) [<c009d588>] (kmem_cache_create) from [<c031ca3c>] (ubi_attach+0x94/0x1608) [<c031ca3c>] (ubi_attach) from [<c031130c>] (ubi_attach_mtd_dev+0x3e4/0xb74) [<c031130c>] (ubi_attach_mtd_dev) from [<c06732b8>] (ubi_init+0x164/0x21c) [<c06732b8>] (ubi_init) from [<c0009978>] (do_one_initcall+0x3c/0x174) [<c0009978>] (do_one_initcall) from [<c065dd60>] (kernel_init_freeable+0x108/0x1bc)
[<c065dd60>] (kernel_init_freeable) from [<c04fa710>] (kernel_init+0x8/0xf4) [<c04fa710>] (kernel_init) from [<c000a740>] (ret_from_fork+0x14/0x34)
ubi2 error: ubi_attach_mtd_dev: failed to attach mtd12, error -12 UBI error: cannot attach mtd12 block ubiblock0_0: created from ubi0:0(rootfs)
ubi1: background thread "ubi_bgt1d" started, PID 718 bq32k 0-0068: setting system clock to 2018-07-02 09:32:41 UTC (1530523961)
uart-pl011 d0000000.serial: no DMA platform data scsi host0: usb-storage 2-1:1.0
VFS: Mounted root (squashfs filesystem) readonly on device 253:0.
devtmpfs: mounted


Additional observation: 
1. if the ubi background thread starts before the next ubi volume attach gets started, then the duplicate filename problem does not happen. 

  Example of PASS
  ubi0: background thread "ubi_bgt0d" started, PID 721                  ..... background thread started before next ubi attaching message... 
  ubi1: attaching mtd11

2. If the ubi background thread is delayed from starting until after the next ubi volume attach is started, the duplicate filename problem does happen 

  Example of FAIL: 
  ubi0: available PEBs: 180, total reserved PEBs: 656, PEBs reserved for bad PEB handling: 40
  ubi1: attaching mtd11
  ubi0: background thread "ubi_bgt0d" started, PID 714                     ..... background thread started after next ubi attaching message...
  ... 
  sysfs: cannot create duplicate filename '/kernel/slab/:t-0000048'


I am looking for suggestions on how to fix this. 
Any suggestions are greatly appreciated.


Andy Purcell

Re: need help with slub.c duplicate filename '/kernel/slab/:t-0000048' problem

[Christopher Lameter]

See commit commit d50d82faa0c964e31f7a946ba8aba7c715ca7ab0