Thomas Zimmermann <tzimmermann@xxxxxxx> writes:
Hello Thomas,
> Hi
>
> Am 10.06.24 um 10:47 schrieb Thomas Zimmermann:
>> Hi
>>
>> Am 04.06.24 um 10:03 schrieb Peng Fan (OSS):
>>> From: Peng Fan <peng.fan@xxxxxxx>
>>>
>>> If 'info->screen_buffer' locates in vmalloc address space, virt_to_page
>>> will not be able to get correct results. With CONFIG_DEBUG_VM and
>>> CONFIG_DEBUG_VIRTUAL enabled on ARM64, there is dump below:
>>
>> Which graphics driver triggers this bug?
>>
>>> [ 3.536043] ------------[ cut here ]------------
>>> [ 3.540716] virt_to_phys used for non-linear address:
>>> 000000007fc4f540 (0xffff800086001000)
>>> [ 3.552628] WARNING: CPU: 4 PID: 61 at arch/arm64/mm/physaddr.c:12
>>> __virt_to_phys+0x68/0x98
>>> [ 3.565455] Modules linked in:
>>> [ 3.568525] CPU: 4 PID: 61 Comm: kworker/u12:5 Not tainted
>>> 6.6.23-06226-g4986cc3e1b75-dirty #250
>>> [ 3.577310] Hardware name: NXP i.MX95 19X19 board (DT)
>>> [ 3.582452] Workqueue: events_unbound deferred_probe_work_func
>>> [ 3.588291] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
>>> BTYPE=--)
>>> [ 3.595233] pc : __virt_to_phys+0x68/0x98
>>> [ 3.599246] lr : __virt_to_phys+0x68/0x98
>>> [ 3.603276] sp : ffff800083603990
>>> [ 3.677939] Call trace:
>>> [ 3.680393] __virt_to_phys+0x68/0x98
>>> [ 3.684067] drm_fbdev_dma_helper_fb_probe+0x138/0x238
>>> [ 3.689214] __drm_fb_helper_initial_config_and_unlock+0x2b0/0x4c0
>>> [ 3.695385] drm_fb_helper_initial_config+0x4c/0x68
>>> [ 3.700264] drm_fbdev_dma_client_hotplug+0x8c/0xe0
>>> [ 3.705161] drm_client_register+0x60/0xb0
>>> [ 3.709269] drm_fbdev_dma_setup+0x94/0x148
>>>
>>> So add a check 'is_vmalloc_addr'.
>>>
>>> Fixes: b79fe9abd58b ("drm/fbdev-dma: Implement fbdev emulation for
>>> GEM DMA helpers")
>>> Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
>>
>> Reviewed-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
>
> I'm taking back my r-b. The memory is expected to by be physically
> contiguous and vmalloc() won't guarantee that.
>
Agreed.
> Best regards
> Thomas
>
--
Best regards,
Javier Martinez Canillas
Core Platforms
Red Hat
