linux-kernel - Re: [PATCH bpf-next 1/3] mm/vmalloc: introduce vmalloc

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Date:   Fri, 15 Jul 2022 00:24:15 +0000
From:   Song Liu <songliubraving@...com>
To:     Uladzislau Rezki <urezki@...il.com>
CC:     Christoph Hellwig <hch@...radead.org>, Song Liu <song@...nel.org>,
        bpf <bpf@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-modules@...r.kernel.org" <linux-modules@...r.kernel.org>,
        "mcgrof@...nel.org" <mcgrof@...nel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "mhiramat@...nel.org" <mhiramat@...nel.org>,
        "naveen.n.rao@...ux.ibm.com" <naveen.n.rao@...ux.ibm.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "anil.s.keshavamurthy@...el.com" <anil.s.keshavamurthy@...el.com>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "dave@...olabs.net" <dave@...olabs.net>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        Kernel Team <Kernel-team@...com>,
        "x86@...nel.org" <x86@...nel.org>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "rick.p.edgecombe@...el.com" <rick.p.edgecombe@...el.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: Re: [PATCH bpf-next 1/3] mm/vmalloc: introduce vmalloc_exec which
 allocates RO+X memory



> On Jul 14, 2022, at 11:15 AM, Uladzislau Rezki <urezki@...il.com> wrote:
> 
> On Thu, Jul 14, 2022 at 04:54:40AM +0000, Song Liu wrote:
>> 
>> 
>>> On Jul 13, 2022, at 9:23 PM, Christoph Hellwig <hch@...radead.org> wrote:
>>> 
>>> On Wed, Jul 13, 2022 at 03:49:45PM +0000, Song Liu wrote:
>>>> 
>>>> 
>>>>> On Jul 13, 2022, at 3:08 AM, Christoph Hellwig <hch@...radead.org> wrote:
>>>>> 
>>>>> NAK.  This is not something that should be an exported public API
>>>>> ever.
>>>> 
>>>> Hmm.. I will remove EXPORT_SYMBOL_GPL (if we ever do a v2 of this..)
>>> 
>>> Even without that it really is not a vmalloc API anyway.  
>> 
>> This ...
>> 
>>> Executable
>>> memory needs to be written first, so we should allocate it in that state
>>> and only mark it executable after that write has completed.
>> 
>> ... and this are two separate NAKs.
>> 
>> For the first NAK, I agree that my version is another layer on top of 
>> vmalloc. But what do you think about Peter's idea? AFAICT, that fits
>> well in vmalloc logic. 
>> 
> I am not able to find the patch/change to see what you have done.

vger dropped my patch again. :(

> But
> please do not build a new allocator on top of vmalloc code. We have
> three different ones what make things to be complicated :)

It was a bpf_prog_pack like allocator, but named as vmalloc_exec(), 
vfree_exec(). I guess I have got enough NAKs for it. 

Thanks,
Song