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From: Song Liu <songliubraving@fb.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>, Song Liu <song@kernel.org>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	bpf <bpf@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Kernel Team <Kernel-team@fb.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
	Christoph Hellwig <hch@infradead.org>,
	Andrii Nakryiko <andrii@kernel.org>
Subject: Re: [PATCH bpf] bpf: invalidate unused part of bpf_prog_pack
Date: Fri, 22 Apr 2022 01:31:17 +0000	[thread overview]
Message-ID: <4EA80DBB-4194-4FC4-866F-7088C2107E17@fb.com> (raw)
In-Reply-To: <CAHk-=wgW2vxREeH0Bgr8hGxVavfRsNAX3cyaS9eCcg9A77zhLw@mail.gmail.com>

Hi Linus,

> On Apr 21, 2022, at 4:10 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> 
> On Thu, Apr 21, 2022 at 3:52 PM Song Liu <songliubraving@fb.com> wrote:
>> 
>> I think this won’t work, as set_memory_ro makes all the aliases of
>> these pages read only.
> 
> Argh. I thought we only did that for the whole memory type thing
> (history: nasty machine checks possible on some hardware if you mix
> memory types for the same physical page with virtual mappings), but if
> we do it for RO too, then yeah.
> 
> It's sad to use that horrid machinery for basically non-live code, but
> whatever.

I guess we will stick with bpf_arch_text_copy(), and we will keep the 
Invalidation at BPF program free time?

I will reorder and resend pending patches. Then we can decide which ones
to ship with 5.18. 

Thanks,
Song

  parent reply	other threads:[~2022-04-22  1:31 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-21  7:22 Song Liu
2022-04-21 17:09 ` Linus Torvalds
2022-04-21 18:24   ` Alexei Starovoitov
     [not found]     ` <CAHk-=whFeBezdSrPy31iYv-UZNnNavymrhqrwCptE4uW8aeaHw@mail.gmail.com>
2022-04-21 19:40       ` Song Liu
2022-04-21 21:28         ` Linus Torvalds
2022-04-21 21:52           ` Song Liu
     [not found]             ` <CAHk-=wi62LDc5B3DOr5pyVtOUOuLkLzHvmZQApH9q=raqaGkUg@mail.gmail.com>
2022-04-21 22:51               ` Song Liu
     [not found]                 ` <CAHk-=wgW2vxREeH0Bgr8hGxVavfRsNAX3cyaS9eCcg9A77zhLw@mail.gmail.com>
2022-04-22  1:31                   ` Song Liu [this message]
2022-04-22  7:31                 ` Peter Zijlstra
2022-04-23  5:25                   ` Song Liu

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