On Thu, 2022-07-14 at 16:41 +0800, Huacai Chen wrote:
> When CONFIG_CPUMASK_OFFSTACK and CONFIG_DEBUG_PER_CPU_MAPS is selected,
> cpu_max_bits_warn() generates a runtime warning similar as below while
> we show /proc/cpuinfo. Fix this by using nr_cpu_ids (the runtime limit)
> instead of NR_CPUS to iterate CPUs.
>
> [ 3.052463] ------------[ cut here ]------------
> [ 3.059679] WARNING: CPU: 3 PID: 1 at include/linux/cpumask.h:108 show_cpuinfo+0x5e8/0x5f0
> [ 3.070072] Modules linked in: efivarfs autofs4
> [ 3.076257] CPU: 0 PID: 1 Comm: systemd Not tainted 5.19-rc5+ #1052
> [ 3.099465] Stack : 9000000100157b08 9000000000f18530 9000000000cf846c 9000000100154000
> [ 3.109127] 9000000100157a50 0000000000000000 9000000100157a58 9000000000ef7430
> [ 3.118774] 90000001001578e8 0000000000000040 0000000000000020 ffffffffffffffff
> [ 3.128412] 0000000000aaaaaa 1ab25f00eec96a37 900000010021de80 900000000101c890
> [ 3.138056] 0000000000000000 0000000000000000 0000000000000000 0000000000aaaaaa
> [ 3.147711] ffff8000339dc220 0000000000000001 0000000006ab4000 0000000000000000
> [ 3.157364] 900000000101c998 0000000000000004 9000000000ef7430 0000000000000000
> [ 3.167012] 0000000000000009 000000000000006c 0000000000000000 0000000000000000
> [ 3.176641] 9000000000d3de08 9000000001639390 90000000002086d8 00007ffff0080286
> [ 3.186260] 00000000000000b0 0000000000000004 0000000000000000 0000000000071c1c
> [ 3.195868] ...
> [ 3.199917] Call Trace:
> [ 3.203941] [<90000000002086d8>] show_stack+0x38/0x14c
> [ 3.210666] [<9000000000cf846c>] dump_stack_lvl+0x60/0x88
> [ 3.217625] [<900000000023d268>] __warn+0xd0/0x100
> [ 3.223958] [<9000000000cf3c90>] warn_slowpath_fmt+0x7c/0xcc
> [ 3.231150] [<9000000000210220>] show_cpuinfo+0x5e8/0x5f0
> [ 3.238080] [<90000000004f578c>] seq_read_iter+0x354/0x4b4
> [ 3.245098] [<90000000004c2e90>] new_sync_read+0x17c/0x1c4
> [ 3.252114] [<90000000004c5174>] vfs_read+0x138/0x1d0
> [ 3.258694] [<90000000004c55f8>] ksys_read+0x70/0x100
> [ 3.265265] [<9000000000cfde9c>] do_syscall+0x7c/0x94
> [ 3.271820] [<9000000000202fe4>] handle_syscall+0xc4/0x160
> [ 3.281824] ---[ end trace 8b484262b4b8c24c ]---
>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> ---
> arch/sh/kernel/cpu/proc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/sh/kernel/cpu/proc.c b/arch/sh/kernel/cpu/proc.c
> index a306bcd6b341..5f6d0e827bae 100644
> --- a/arch/sh/kernel/cpu/proc.c
> +++ b/arch/sh/kernel/cpu/proc.c
> @@ -132,7 +132,7 @@ static int show_cpuinfo(struct seq_file *m, void *v)
>
> static void *c_start(struct seq_file *m, loff_t *pos)
> {
> - return *pos < NR_CPUS ? cpu_data + *pos : NULL;
> + return *pos < nr_cpu_ids ? cpu_data + *pos : NULL;
> }
> static void *c_next(struct seq_file *m, void *v, loff_t *pos)
> {
I build-tested the patch and also booted the patched kernel successfully
on my SH-7785LCR board.
Showing the contents of /proc/cpuinfo works fine, too:
root@tirpitz:~> cat /proc/cpuinfo
machine : SH7785LCR
processor : 0
cpu family : sh4a
cpu type : SH7785
cut : 7.x
cpu flags : fpu perfctr llsc
cache type : split (harvard)
icache size : 32KiB (4-way)
dcache size : 32KiB (4-way)
address sizes : 32 bits physical
bogomips : 599.99
root@tirpitz:~>
Tested-by: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
I am not sure yet whether the change is also correct as I don't know whether
it's possible to change the number of CPUs at runtime on SuperH.
Adrian
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
