Re: [REGRESSION] BUG: KFENCE: memory corruption in drm_gem_put_pages+0x186/0x250

[Bagas Sanjaya <bagasdotme@gmail.com>]

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On Sun, Oct 01, 2023 at 06:32:34PM +0200, Oleksandr Natalenko wrote:
> Hello.
> 
> I've got a VM from a cloud provider, and since v6.5 I observe the following kfence splat in dmesg during boot:
> 
> ```
> BUG: KFENCE: memory corruption in drm_gem_put_pages+0x186/0x250
> 
> Corrupted memory at 0x00000000e173a294 [ ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ] (in kfence-#108):
>  drm_gem_put_pages+0x186/0x250
>  drm_gem_shmem_put_pages_locked+0x43/0xc0
>  drm_gem_shmem_object_vunmap+0x83/0xe0
>  drm_gem_vunmap_unlocked+0x46/0xb0
>  drm_fbdev_generic_helper_fb_dirty+0x1dc/0x310
>  drm_fb_helper_damage_work+0x96/0x170
>  process_one_work+0x254/0x470
>  worker_thread+0x55/0x4f0
>  kthread+0xe8/0x120
>  ret_from_fork+0x34/0x50
>  ret_from_fork_asm+0x1b/0x30
> 
> kfence-#108: 0x00000000cda343af-0x00000000aec2c095, size=3072, cache=kmalloc-4k
> 
> allocated by task 51 on cpu 0 at 14.668667s:
>  drm_gem_get_pages+0x94/0x2b0
>  drm_gem_shmem_get_pages+0x5d/0x110
>  drm_gem_shmem_object_vmap+0xc4/0x1e0
>  drm_gem_vmap_unlocked+0x3c/0x70
>  drm_client_buffer_vmap+0x23/0x50
>  drm_fbdev_generic_helper_fb_dirty+0xae/0x310
>  drm_fb_helper_damage_work+0x96/0x170
>  process_one_work+0x254/0x470
>  worker_thread+0x55/0x4f0
>  kthread+0xe8/0x120
>  ret_from_fork+0x34/0x50
>  ret_from_fork_asm+0x1b/0x30
> 
> freed by task 51 on cpu 0 at 14.668697s:
>  drm_gem_put_pages+0x186/0x250
>  drm_gem_shmem_put_pages_locked+0x43/0xc0
>  drm_gem_shmem_object_vunmap+0x83/0xe0
>  drm_gem_vunmap_unlocked+0x46/0xb0
>  drm_fbdev_generic_helper_fb_dirty+0x1dc/0x310
>  drm_fb_helper_damage_work+0x96/0x170
>  process_one_work+0x254/0x470
>  worker_thread+0x55/0x4f0
>  kthread+0xe8/0x120
>  ret_from_fork+0x34/0x50
>  ret_from_fork_asm+0x1b/0x30
> 
> CPU: 0 PID: 51 Comm: kworker/0:2 Not tainted 6.5.0-pf4 #1 8b557a4173114d86eef7240f7a080080cfc4617e
> Hardware name: Red Hat KVM, BIOS 1.11.0-2.el7 04/01/2014
> Workqueue: events drm_fb_helper_damage_work
> ```
> 
> This repeats a couple of times and then stops.
> 
> Currently, I'm running v6.5.5. So far, there's no impact on how VM functions for me.
> 
> The VGA adapter is as follows: 00:02.0 VGA compatible controller: Cirrus Logic GD 5446
> 

Thanks for the regression report. I'm adding it to regzbot:

#regzbot ^introduced: v6.4..v6.5

-- 
An old man doll... just what I always wanted! - Clara

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