linux-kernel - Re: [RFC v2 0/4] vmalloc_exec for modules and BPF programs

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Message-ID: <20221018145021.GC20131@lst.de>
Date:   Tue, 18 Oct 2022 16:50:21 +0200
From:   Christoph Hellwig <hch@....de>
To:     Song Liu <songliubraving@...a.com>
Cc:     Christoph Hellwig <hch@....de>, Song Liu <song@...nel.org>,
        Linux-MM <linux-mm@...ck.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        X86 ML <x86@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
        Kernel Team <Kernel-team@...com>,
        "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "urezki@...il.com" <urezki@...il.com>
Subject: Re: [RFC v2 0/4] vmalloc_exec for modules and BPF programs

On Mon, Oct 17, 2022 at 04:23:52PM +0000, Song Liu wrote:
> > Well, nothing explains what the method is to avoid having memory
> > that is mapped writable and executable at the same time, which really
> > could use some explanation here (and in the main patch as well).
> 
> Thanks for the feedback. I will add this. 
> 
> Does the code look good to you? I personally think patch 1, 2, 4 could
> ship with a little more work. 

I only took a quick look and I'm not sure how the W^X actually works.
Yes, it alls into the text poke helpers, but how do these work on
less than page sized allocations?