[PATCH v2] libnvdimm/pmem: Fix blk_cleanup_disk() usage

[Jens Axboe]

On 6/7/21 5:52 PM, Dan Williams wrote:
> The queue_to_disk() helper can not be used after del_gendisk()
> communicate @disk via the pgmap->owner.
> 
> Otherwise, queue_to_disk() returns NULL resulting in the splat below.
> 
>  Kernel attempted to read user page (330) - exploit attempt? (uid: 0)
>  BUG: Kernel NULL pointer dereference on read at 0x00000330
>  Faulting instruction address: 0xc000000000906344
>  Oops: Kernel access of bad area, sig: 11 [#1]
>  [..]
>  NIP [c000000000906344] pmem_pagemap_cleanup+0x24/0x40
>  LR [c0000000004701d4] memunmap_pages+0x1b4/0x4b0
>  Call Trace:
>  [c000000022cbb9c0] [c0000000009063c8] pmem_pagemap_kill+0x28/0x40 (unreliable)
>  [c000000022cbb9e0] [c0000000004701d4] memunmap_pages+0x1b4/0x4b0
>  [c000000022cbba90] [c0000000008b28a0] devm_action_release+0x30/0x50
>  [c000000022cbbab0] [c0000000008b39c8] release_nodes+0x2f8/0x3e0
>  [c000000022cbbb60] [c0000000008ac440] device_release_driver_internal+0x190/0x2b0
>  [c000000022cbbba0] [c0000000008a8450] unbind_store+0x130/0x170

Applied, thanks.

-- 
Jens Axboe