Re: [bug report] kmemleak issue observed during blktests

[Ming Lei <ming.lei@redhat.com>]

On Wed, Jul 16, 2025 at 03:50:34PM +0800, Yu Kuai wrote:
> Hi,
> 
> 在 2025/07/16 9:54, Jens Axboe 写道:
> > unreferenced object 0xffff8882e7fbb000 (size 2048):
> >    comm "check", pid 10460, jiffies 4324980514
> >    hex dump (first 32 bytes):
> >      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> >      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
> >    backtrace (crc c47e6a37):
> >      __kvmalloc_node_noprof+0x55d/0x7a0
> >      sbitmap_init_node+0x15a/0x6a0
> >      kyber_init_hctx+0x316/0xb90
> >      blk_mq_init_sched+0x416/0x580
> >      elevator_switch+0x18b/0x630
> >      elv_update_nr_hw_queues+0x219/0x2c0
> >      __blk_mq_update_nr_hw_queues+0x36a/0x6f0
> >      blk_mq_update_nr_hw_queues+0x3a/0x60
> >      find_fallback+0x510/0x540 [nbd]
> 
> This is werid, and I check the code that it's impossible
> blk_mq_update_nr_hw_queues() can be called from find_fallback().

Yes.

> Does kmemleak show wrong backtrace?

I tried to run blktests block/005 over nbd, but can't reproduce this
kmemleak report after setting up the detector.

Yi, can you share your reproducer?


Thanks
Ming