Re: [PATCH] blk-mq: fix possible memleak when register 'hctx' failed

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

On Thu, Nov 17, 2022 at 10:29:40AM +0800, Ye Bin wrote:
> From: Ye Bin <yebin10@huawei.com>
> 
> There's issue as follows when do fault injection test:
> unreferenced object 0xffff888132a9f400 (size 512):
>   comm "insmod", pid 308021, jiffies 4324277909 (age 509.733s)
>   hex dump (first 32 bytes):
>     00 00 00 00 00 00 00 00 08 f4 a9 32 81 88 ff ff  ...........2....
>     08 f4 a9 32 81 88 ff ff 00 00 00 00 00 00 00 00  ...2............
>   backtrace:
>     [<00000000e8952bb4>] kmalloc_node_trace+0x22/0xa0
>     [<00000000f9980e0f>] blk_mq_alloc_and_init_hctx+0x3f1/0x7e0
>     [<000000002e719efa>] blk_mq_realloc_hw_ctxs+0x1e6/0x230
>     [<000000004f1fda40>] blk_mq_init_allocated_queue+0x27e/0x910
>     [<00000000287123ec>] __blk_mq_alloc_disk+0x67/0xf0
>     [<00000000a2a34657>] 0xffffffffa2ad310f
>     [<00000000b173f718>] 0xffffffffa2af824a
>     [<0000000095a1dabb>] do_one_initcall+0x87/0x2a0
>     [<00000000f32fdf93>] do_init_module+0xdf/0x320
>     [<00000000cbe8541e>] load_module+0x3006/0x3390
>     [<0000000069ed1bdb>] __do_sys_finit_module+0x113/0x1b0
>     [<00000000a1a29ae8>] do_syscall_64+0x35/0x80
>     [<000000009cd878b0>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
> 
> Fault injection context as follows:
>  kobject_add
>  blk_mq_register_hctx
>  blk_mq_sysfs_register
>  blk_register_queue
>  device_add_disk
>  null_add_dev.part.0 [null_blk]
> 
> As 'blk_mq_register_hctx' may already add some objects when failed halfway,
> but there isn't do fallback, caller don't know which objects add failed.
> To solve above issue just do fallback when add objects failed halfway in
> 'blk_mq_register_hctx'.
> 
> Signed-off-by: Ye Bin <yebin10@huawei.com>

Reviewed-by: Ming Lei <ming.lei@redhat.com>


Thanks,
Ming