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Date:   Mon, 2 Oct 2023 17:40:43 +0700
From:   Bagas Sanjaya <bagasdotme@gmail.com>
To:     Oleksandr Natalenko <oleksandr@natalenko.name>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc:     Linux Media Mailing List <linux-media@vger.kernel.org>,
        linaro-mm-sig@lists.linaro.org,
        Linux DRI Development <dri-devel@lists.freedesktop.org>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.com>,
        Linux Regressions <regressions@lists.linux.dev>
Subject: Re: [REGRESSION] BUG: KFENCE: memory corruption in
 drm_gem_put_pages+0x186/0x250
Message-ID: <ZRqeK_OgfDS4liMt@debian.me>
References: <13360591.uLZWGnKmhe@natalenko.name>
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On Sun, Oct 01, 2023 at 06:32:34PM +0200, Oleksandr Natalenko wrote:
> Hello.
>=20
> I've got a VM from a cloud provider, and since v6.5 I observe the followi=
ng kfence splat in dmesg during boot:
>=20
> ```
> BUG: KFENCE: memory corruption in drm_gem_put_pages+0x186/0x250
>=20
> 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
>=20
> kfence-#108: 0x00000000cda343af-0x00000000aec2c095, size=3D3072, cache=3D=
kmalloc-4k
>=20
> 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
>=20
> 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
>=20
> CPU: 0 PID: 51 Comm: kworker/0:2 Not tainted 6.5.0-pf4 #1 8b557a4173114d8=
6eef7240f7a080080cfc4617e
> Hardware name: Red Hat KVM, BIOS 1.11.0-2.el7 04/01/2014
> Workqueue: events drm_fb_helper_damage_work
> ```
>=20
> This repeats a couple of times and then stops.
>=20
> Currently, I'm running v6.5.5. So far, there's no impact on how VM functi=
ons for me.
>=20
> The VGA adapter is as follows: 00:02.0 VGA compatible controller: Cirrus =
Logic GD 5446
>=20

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

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

--=20
An old man doll... just what I always wanted! - Clara

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