[PATCH] arm64: cacheinfo: Fix incorrect assignment of signed error value to unsigned fw_level

[Sudeep Holla]

Hi Will,

On Mon, Aug 08, 2022 at 09:46:40AM +0100, Sudeep Holla wrote:
> Though acpi_find_last_cache_level() always returned signed value and the
> document states it will return any errors caused by lack of a PPTT table,
> it never returned negative values before.
> 
> Commit 0c80f9e165f8 ("ACPI: PPTT: Leave the table mapped for the runtime usage")
> however changed it by returning -ENOENT if no PPTT was found. The value
> returned from acpi_find_last_cache_level() is then assigned to unsigned
> fw_level.
> 
> It will result in the number of cache leaves calculated incorrectly as
> a huge value which will then cause the following warning from __alloc_pages
> as the order would be great than MAX_ORDER because of incorrect and huge
> cache leaves value.
> 
>   |  WARNING: CPU: 0 PID: 1 at mm/page_alloc.c:5407 __alloc_pages+0x74/0x314
>   |  Modules linked in:
>   |  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.19.0-10393-g7c2a8d3ac4c0 #73
>   |  pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>   |  pc : __alloc_pages+0x74/0x314
>   |  lr : alloc_pages+0xe8/0x318
>   |  Call trace:
>   |   __alloc_pages+0x74/0x314
>   |   alloc_pages+0xe8/0x318
>   |   kmalloc_order_trace+0x68/0x1dc
>   |   __kmalloc+0x240/0x338
>   |   detect_cache_attributes+0xe0/0x56c
>   |   update_siblings_masks+0x38/0x284
>   |   store_cpu_topology+0x78/0x84
>   |   smp_prepare_cpus+0x48/0x134
>   |   kernel_init_freeable+0xc4/0x14c
>   |   kernel_init+0x2c/0x1b4
>   |   ret_from_fork+0x10/0x20
> 
> Fix the same by changing fw_level to be signed integer and return the
> error from init_cache_level() early in case of error.
>

Can you pick up this for next round of fixes ?
The original report can be found @[1]

-- 
Regards,
Sudeep

[1] https://lore.kernel.org/all/CA+QYu4rPbfH-4wNR06Vn=31RCGKFFEB-KRskn52Jtig_UugYzg@mail.gmail.com/