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

From: Thomas Zimmermann
Date: Thu Oct 05 2023 - 09:56:43 EST


Hi

Am 01.10.23 um 18:32 schrieb Oleksandr Natalenko:
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

There's nothing special about the cirrus driver. Can you please provide the full output of 'lspci -v' ?

Would you be able to bisect this bug?

Best regards
Thomas


Please check.

Thanks.


--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)

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