From: Vincent Chen <vincent.chen@xxxxxxxxxx> commit c749bb2d554825e007cbc43b791f54e124dadfce upstream. 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@xxxxxxxxxxxxxxx Signed-off-by: Vincent Chen <vincent.chen@xxxxxxxxxx> Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx> Reviewed-by: Yash Shah <yash.shah@xxxxxxxxxx> Tested-by: Yash Shah <yash.shah@xxxxxxxxxx> Signed-off-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx> [Palmer: back-ported to 4.19] Signed-off-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/riscv/kernel/setup.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -19,6 +19,7 @@ * to the Free Software Foundation, Inc., */ +#include <linux/bootmem.h> #include <linux/init.h> #include <linux/mm.h> #include <linux/memblock.h> @@ -187,6 +188,7 @@ static void __init setup_bootmem(void) set_max_mapnr(PFN_DOWN(mem_size)); max_low_pfn = PFN_DOWN(memblock_end_of_DRAM()); + max_pfn = max_low_pfn; #ifdef CONFIG_BLK_DEV_INITRD setup_initrd();
