ACK/cmnt: [PATCH 1/1][SRU][F/G][RISCV] riscv: set max_pfn to the PFN of the last page

[Kleber Souza]

On 05.05.20 11:27, Colin King wrote:
> From: Vincent Chen <vincent.chen at sifive.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1876885
> 
> The current max_pfn equals to zero. In this case, I found it caused users
> cannot get some page information through /proc such as kpagecount in v5.6
> kernel because of new sanity checks. The following message is displayed by
> stress-ng test suite with the command "stress-ng --verbose --physpage 1 -t
> 1" on HiFive unleashed board.
> 
>  # stress-ng --verbose --physpage 1 -t 1
>  stress-ng: debug: [109] 4 processors online, 4 processors configured
>  stress-ng: info: [109] dispatching hogs: 1 physpage
>  stress-ng: debug: [109] cache allocate: reducing cache level from L3 (too high) to L0
>  stress-ng: debug: [109] get_cpu_cache: invalid cache_level: 0
>  stress-ng: info: [109] cache allocate: using built-in defaults as no suitable cache found
>  stress-ng: debug: [109] cache allocate: default cache size: 2048K
>  stress-ng: debug: [109] starting stressors
>  stress-ng: debug: [109] 1 stressor spawned
>  stress-ng: debug: [110] stress-ng-physpage: started [110] (instance 0)
>  stress-ng: error: [110] stress-ng-physpage: cannot read page count for address 0x3fd34de000 in /proc/kpagecount, errno=0 (Success)
>  stress-ng: error: [110] stress-ng-physpage: cannot read page count for address 0x3fd32db078 in /proc/kpagecount, errno=0 (Success)
>  ...
>  stress-ng: error: [110] stress-ng-physpage: cannot read page count for address 0x3fd32db078 in /proc/kpagecount, errno=0 (Success)
>  stress-ng: debug: [110] stress-ng-physpage: exited [110] (instance 0)
>  stress-ng: debug: [109] process [110] terminated
>  stress-ng: info: [109] successful run completed in 1.00s
>  #
> 
> After applying this patch, the kernel can pass the test.
> 
>  # stress-ng --verbose --physpage 1 -t 1
>  stress-ng: debug: [104] 4 processors online, 4 processors configured stress-ng: info: [104] dispatching hogs: 1 physpage
>  stress-ng: info: [104] cache allocate: using defaults, can't determine cache details from sysfs
>  stress-ng: debug: [104] cache allocate: default cache size: 2048K
>  stress-ng: debug: [104] starting stressors
>  stress-ng: debug: [104] 1 stressor spawned
>  stress-ng: debug: [105] stress-ng-physpage: started [105] (instance 0) stress-ng: debug: [105] stress-ng-physpage: exited [105] (instance 0) stress-ng: debug: [104] process [105] terminated
>  stress-ng: info: [104] successful run completed in 1.01s
>  #
> 
> Cc: stable at vger.kernel.org
> Signed-off-by: Vincent Chen <vincent.chen at sifive.com>
> Reviewed-by: Anup Patel <anup at brainfault.org>
> Reviewed-by: Yash Shah <yash.shah at sifive.com>
> Tested-by: Yash Shah <yash.shah at sifive.com>
> Signed-off-by: Palmer Dabbelt <palmerdabbelt at google.com>
> (cherry picked from commit c749bb2d554825e007cbc43b791f54e124dadfce linux-next)
> Signed-off-by: Colin Ian King <colin.king at canonical.com>

This patch was already merged into Linus' tree, so we can remove the 'linux-next'
part from the provenance above.

Acked-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>

> ---
>  arch/riscv/mm/init.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index b55be44ff9bd..5b813532db59 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -150,7 +150,8 @@ void __init setup_bootmem(void)
>  	memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);
>  
>  	set_max_mapnr(PFN_DOWN(mem_size));
> -	max_low_pfn = PFN_DOWN(memblock_end_of_DRAM());
> +	max_pfn = PFN_DOWN(memblock_end_of_DRAM());
> +	max_low_pfn = max_pfn;
>  
>  #ifdef CONFIG_BLK_DEV_INITRD
>  	setup_initrd();
>