Hi, Geert,
On Tue, Jul 12, 2022 at 4:33 PM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
Hi Huacai,
Thanks for your patch!
On Tue, Jul 12, 2022 at 9:53 AM Huacai Chen <chenhuacai@xxxxxxxxxxx> wrote:
When CONFIG_CPUMASK_OFFSTACK and CONFIG_DEBUG_PER_CPU_MAPS is selected,
DEBUG_PER_CPU_MAPS depends on SMP, which is not supported on m68k,
and thus cannot be enabled.
This patch is derived from MIPS and LoongArch, I search all
architectures and change those that look the same as MIPS and
LoongArch.
And the warning message below is also a copy-paste from LoongArch, sorry.
Since M68K doesn't support SMP, then this patch seems to make no
difference, but does it make sense to keep consistency across all
architectures?
Huacai
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
efivarfs on m68k?
EFIVAR_FS depends on EFI depends on !CPU_BIG_ENDIAN
[ 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>
Does this need a Fixes tag, so we know when the problem was introduced?
--- a/arch/m68k/kernel/setup_no.c
+++ b/arch/m68k/kernel/setup_no.c
@@ -201,7 +201,7 @@ 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 ? ((void *) 0x12345678) : NULL;
+ return *pos < nr_cpu_ids ? ((void *) 0x12345678) : NULL;
}
include/linux/cpumask.h has:
#if NR_CPUS == 1
#define nr_cpu_ids 1U
so on m68k, both evaluate to the same value?
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
