Re: [PATCH 2/4] fs: Remove FIRMWARE_PREALLOC_BUFFER from kernel_read_file() enums

[Matthew Wilcox]

On Fri, Jul 10, 2020 at 02:00:32PM -0700, Scott Branden wrote:
> > @@ -950,8 +951,8 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size,
> >   		goto out;
> >   	}
> > -	if (id != READING_FIRMWARE_PREALLOC_BUFFER)
> > -		*buf = vmalloc(i_size);
> > +	if (!*buf)
> The assumption that *buf is always NULL when id !=
> READING_FIRMWARE_PREALLOC_BUFFER doesn't appear to be correct.
> I get unhandled page faults due to this change on boot.

Did it give you a stack backtrace?