netdev - Re: [PATCH] x86/dumpstack/64: Add guard pages to stack

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Date:   Fri, 17 Sep 2021 12:21:24 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     王贇 <yun.wang@...ux.alibaba.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        "open list:PERFORMANCE EVENTS SUBSYSTEM" 
        <linux-perf-users@...r.kernel.org>,
        "open list:PERFORMANCE EVENTS SUBSYSTEM" 
        <linux-kernel@...r.kernel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <netdev@...r.kernel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <bpf@...r.kernel.org>, jroedel@...e.de, x86@...nel.org,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH] x86/dumpstack/64: Add guard pages to stack_info

On Fri, Sep 17, 2021 at 11:02:07AM +0800, 王贇 wrote:
> 
> 
> On 2021/9/16 下午6:02, Peter Zijlstra wrote:
> [snip]
> >  
> > +static __always_inline bool in_stack_guard(void *addr, void *begin, void *end)
> > +{
> > +#ifdef CONFIG_VMAP_STACK
> > +	if (addr > (begin - PAGE_SIZE))
> > +		return true;
> 
> After fix this logical as:
> 
>   addr >= (begin - PAGE_SIZE) && addr < begin
> 
> it's working.

Shees, I seem to have a knack for getting it wrong, don't I. Thanks!

Anyway, I'll ammend the commit locally, but I'd really like some
feedback from Andy, who wrote all that VIRT_STACK stuff in the first
place.