Re: [PATCHv5 6/7] block: protect wbt_lat_usec using q->elevator_lock

[Nilay Shroff <nilay@linux.ibm.com>]

On 3/4/25 11:48 AM, kernel test robot wrote:
> 
> 
> Hello,
> 
> kernel test robot noticed "sysfs:cannot_create_duplicate_filename" on:
> 
> commit: 2951441c42530952368c2bae7190ea8779b2385f ("[PATCHv5 6/7] block: protect wbt_lat_usec using q->elevator_lock")
> url: https://github.com/intel-lab-lkp/linux/commits/Nilay-Shroff/block-acquire-q-limits_lock-while-reading-sysfs-attributes/20250226-204836
> base: https://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git for-next
> patch link: https://lore.kernel.org/all/20250226124006.1593985-7-nilay@linux.ibm.com/
> patch subject: [PATCHv5 6/7] block: protect wbt_lat_usec using q->elevator_lock
> 
> in testcase: boot
> 
> config: x86_64-randconfig-074-20250228
> compiler: gcc-12
> test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
> 
> (please refer to attached dmesg/kmsg for entire log/backtrace)
> 
> 
> +----------------------------------------+------------+------------+
> |                                        | 96ec4f2440 | 2951441c42 |
> +----------------------------------------+------------+------------+
> | sysfs:cannot_create_duplicate_filename | 0          | 12         |
> +----------------------------------------+------------+------------+
> 
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <oliver.sang@intel.com>
> | Closes: https://lore.kernel.org/oe-lkp/202503041413.872983bd-lkp@intel.com
> 
> 
> [   14.648633][    T1] Non-volatile memory driver v1.3
> [   14.649743][    T1] telclk_interrupt = 0xf non-mcpbl0010 hw.
> [   14.650659][    T1] usbcore: registered new interface driver xillyusb
> [   14.658940][    T1] zram: Added device: zram0
> [   14.659758][   T11] Floppy drive(s): fd0 is 2.88M AMI BIOS
> [   14.662273][    T1] sysfs: cannot create duplicate filename '/devices/virtual/block/nullb0/queue/wbt_lat_usec'
> [   14.663506][    T1] CPU: 0 UID: 0 PID: 1 Comm: swapper Not tainted 6.14.0-rc3-00270-g2951441c4253 #1 adcfde6e4f1dd47f52d455fb462243a4f271be2a
> [   14.664847][    T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> [   14.665952][    T1] Call Trace:
> [   14.666355][    T1]  <TASK>
> [ 14.666473][ T1] dump_stack_lvl (kbuild/src/consumer/lib/dump_stack.c:123 (discriminator 1)) 
> [ 14.666473][ T1] dump_stack (kbuild/src/consumer/lib/dump_stack.c:130) 
> [ 14.666473][ T1] sysfs_warn_dup (kbuild/src/consumer/fs/sysfs/dir.c:32) 
> [ 14.666473][ T1] sysfs_add_file_mode_ns (kbuild/src/consumer/fs/sysfs/file.c:318) 
> 
> 
> The kernel config and materials to reproduce are available at:
> https://download.01.org/0day-ci/archive/20250304/202503041413.872983bd-lkp@intel.com
> 
Sorry, but there was a stale entry left over for wbt_lat_usec attribute 
causing the observed symptom.I will be sending next patchset with the fix.

Thanks,
--Nilay