Re: [bug report] kmemleak issue observed during blktests

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

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().

Does kmemleak show wrong backtrace?

Thanks,
Kuai

>      nbd_send_cmd+0x24b/0x1480 [nbd]
>      configfs_write_iter+0x2ae/0x470
>      vfs_write+0x524/0xe70
>      ksys_write+0xff/0x200
>      do_syscall_64+0x98/0x3c0
>      entry_SYSCALL_64_after_hwframe+0x76/0x7e