Re: Re: [PATCH] drivers/video/fbdev/core/fbmem.c: add pointer judgment

 > On Wed, May 19, 2021 at 08:00:28PM +0800, songqiang wrote:

quoted

Signed-off-by: songqiang <redacted>

From: "Matthew Wilcox <willy@infradead.org>"

quoted

You need to explain:

- Why you think this patch is needed
- Did you observe a problem at runtime?
- Is this the output from some checking tool?
- Why this is the right way to address the problem

On Thu, May 20, 2021 at 7:58 AM 宋强 [off-list ref] wrote:

I find null pointer bug when I debug the kernel of loongson，I think the function fb_set_suspend()
add pointer judgment will more friendly.

When replying to emails on the list, please remember

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The information from your reply should be part of the patch description when
you send a patch, see
https://www.kernel.org/doc/html/v4.17/process/submitting-patches.html

[  102.011018] Call Trace:

[  102.013443] [<ffffffff81068e10>] fb_set_suspend+0x50/0x80
[  102.018819] [<ffffffffc0061aa0>] loongson_drm_suspend+0x1a0/0x340 [loongson]
[  102.025827] [<ffffffffc0061c58>] loongson_pmops_freeze+0x18/0x40 [loongson]
[  102.032748] [<ffffffff81008fd4>] pci_pm_freeze+0x94/0x240
[  102.038114] [<ffffffff815377e0>] dpm_run_callback.isra.5+0x20/0x140
[  102.044341] [<ffffffff81539608>] __device_suspend+0x2c8/0x740

It looks like the check would actually belong into the loongson_drm driver.
The driver is not upstream yet, but I assume you have the source for it, so
try to fix the bug there and send the patch to the owners of that driver.

       Arnd