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Message-ID: <Y0Wk0WD6CL4aFEIi@yury-laptop>
Date: Tue, 11 Oct 2022 10:16:01 -0700
From: Yury Norov <yury.norov@...il.com>
To: Andrew Jones <ajones@...tanamicro.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>, lkp@...ts.01.org,
lkp@...el.com, Linux Memory Management List <linux-mm@...ck.org>,
linux-kernel@...r.kernel.org
Subject: Re: [oliver.sang@...el.com: [cpumask] b9a7ecc71f:
WARNING:at_include/linux/cpumask.h:#__is_kernel_percpu_address]
> Hi Yury,
>
> I just wanted to report that the warning fires when doing
> 'cat /proc/cpuinfo' on at least x86 and riscv. I don't think
> those are false positives. I'm guessing a patch should be
> something like the following diff. If you haven't already
> addressed this and I'm not off in left field, then I guess
> we should integrate it into your series.
>
> Thanks,
> drew
Hi Andrew,
Can you please send it as a patch with a description?
>
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index 4aa8cd749441..4c5dfa230d4b 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -166,9 +166,12 @@ static void print_mmu(struct seq_file *f)
>
> static void *c_start(struct seq_file *m, loff_t *pos)
> {
> - *pos = cpumask_next(*pos - 1, cpu_online_mask);
> - if ((*pos) < nr_cpu_ids)
> - return (void *)(uintptr_t)(1 + *pos);
> + if (*pos < nr_cpu_ids) {
> + *pos = cpumask_next(*pos - 1, cpu_online_mask);
> + if ((*pos) < nr_cpu_ids)
Braces around *pos are not needed.
> + return (void *)(uintptr_t)(1 + *pos);
> + }
> +
> return NULL;
> }
>
> diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
> index 099b6f0d96bd..2ea614e78e28 100644
> --- a/arch/x86/kernel/cpu/proc.c
> +++ b/arch/x86/kernel/cpu/proc.c
> @@ -153,9 +153,12 @@ static int show_cpuinfo(struct seq_file *m, void *v)
>
> static void *c_start(struct seq_file *m, loff_t *pos)
> {
> - *pos = cpumask_next(*pos - 1, cpu_online_mask);
> - if ((*pos) < nr_cpu_ids)
> - return &cpu_data(*pos);
> + if (*pos < nr_cpu_ids) {
> + *pos = cpumask_next(*pos - 1, cpu_online_mask);
> + if ((*pos) < nr_cpu_ids)
Here too.
Thanks,
Yury
> + return &cpu_data(*pos);
> + }
> +
> return NULL;
> }
>
> >
> > > I suspect that to avoid any automation noise, you should just rebase
> > > so that the fixes come first. Otherwise we'll end up wasting a lot of
> > > time on the noise.
> > >
> > > This is not that different from introducing new buil;d-time warnings:
> > > the things they point out need to be fixed before the warning can be
> > > integrated, or it causes bisection problems.
> >
> > OK, I'll reorder the patches. Thanks for your help.
> >
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