Re: [PATCH] null_blk: fix kmemleak by releasing references to fault configfs items

[Jens Axboe <axboe@kernel.dk>]

On 1/12/26 10:39 AM, Nilay Shroff wrote:
> When CONFIG_BLK_DEV_NULL_BLK_FAULT_INJECTION is enabled, the null-blk
> driver sets up fault injection support by creating the timeout_inject,
> requeue_inject, and init_hctx_fault_inject configfs items as children
> of the top-level nullb configfs group.
> 
> However, when the nullb device is removed, the references taken to
> these fault-config configfs items are not released. As a result,
> kmemleak reports a memory leak, for example:
> 
> unreferenced object 0xc00000021ff25c40 (size 32):
>   comm "mkdir", pid 10665, jiffies 4322121578
>   hex dump (first 32 bytes):
>     69 6e 69 74 5f 68 63 74 78 5f 66 61 75 6c 74 5f  init_hctx_fault_
>     69 6e 6a 65 63 74 00 88 00 00 00 00 00 00 00 00  inject..........
>   backtrace (crc 1a018c86):
>     __kmalloc_node_track_caller_noprof+0x494/0xbd8
>     kvasprintf+0x74/0xf4
>     config_item_set_name+0xf0/0x104
>     config_group_init_type_name+0x48/0xfc
>     fault_config_init+0x48/0xf0
>     0xc0080000180559e4
>     configfs_mkdir+0x304/0x814
>     vfs_mkdir+0x49c/0x604
>     do_mkdirat+0x314/0x3d0
>     sys_mkdir+0xa0/0xd8
>     system_call_exception+0x1b0/0x4f0
>     system_call_vectored_common+0x15c/0x2ec
> 
> Fix this by explicitly releasing the references to the fault-config
> configfs items when dropping the reference to the top-level nullb
> configfs group.

Seems like this should have a fixes and stable tag, too?

-- 
Jens Axboe