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Date:   Mon, 2 Oct 2023 17:42:42 +0700
From:   Bagas Sanjaya <bagasdotme@gmail.com>
To:     Oleksandr Natalenko <oleksandr@natalenko.name>,
        linux-kernel@vger.kernel.org
Cc:     linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
        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: <ZRqeoiZ2ayrAR6AV@debian.me>
References: <13360591.uLZWGnKmhe@natalenko.name>
 <ZRoEqEPxPAz3QlEz@debian.me>
 <2701570.mvXUDI8C0e@natalenko.name>
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On Mon, Oct 02, 2023 at 08:20:15AM +0200, Oleksandr Natalenko wrote:
> Hello.
>=20
> On pond=C4=9Bl=C3=AD 2. =C5=99=C3=ADjna 2023 1:45:44 CEST Bagas Sanjaya w=
rote:
> > 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 fol=
lowing 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, cach=
e=3Dkmalloc-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 8b557a41731=
14d86eef7240f7a080080cfc4617e
> > > 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 fu=
nctions for me.
> > >=20
> > > The VGA adapter is as follows: 00:02.0 VGA compatible controller: Cir=
rus Logic GD 5446
> > >=20
> >=20
> > Do you have this issue on v6.4?
>=20
> No, I did not have this issue with v6.4.
>=20

Then proceed with kernel bisection. You can refer to
Documentation/admin-guide/bug-bisect.rst in the kernel sources for the
process.

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

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