From: Linus Torvalds <torvalds@linux-foundation.org>
To: Song Liu <songliubraving@fb.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Luis Chamberlain <mcgrof@kernel.org>, Song Liu <song@kernel.org>,
bpf <bpf@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
open 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>,
Claudio Imbrenda <imbrenda@linux.ibm.com>
Subject: Re: [PATCH v4 bpf 0/4] vmalloc: bpf: introduce VM_ALLOW_HUGE_VMAP
Date: Sat, 16 Apr 2022 13:30:47 -0700 [thread overview]
Message-ID: <CAHk-=wiMCndbBvGSmRVvsuHFWC6BArv-OEG2Lcasih=B=7bFNQ@mail.gmail.com> (raw)
In-Reply-To: <4AD023F9-FBCE-4C7C-A049-9292491408AA@fb.com>
On Sat, Apr 16, 2022 at 12:55 PM Song Liu <songliubraving@fb.com> wrote:
>
> Based on this analysis, I think we should either
> 1) ship the whole set with 5.18; or
> 2) ship 1/4, 3/4, and 4/4 with 5.18, and 2/4 with 5.19.
Honestly, I think the proper thing to do is
- apply #1, because yes, that "use huge pages" should be an opt-in.
- but just disable hugepages for now.
I think those games with set_memory_nx() and friends just show how
rough this all is right now.
In fact, I personally think that the whole bpf 'prog_pack' stuff
should probably be disabled. It looks incredible broken to me right
now.
Unless I mis-read it, it does a "module_alloc()" to allocate the vmap
area, and then just marks it executable without having even
initialized the pages. Am I missing something? So now we have random
kernel memory that is marked executable.
Sure, it's also marked RO, but who cares? It's random data that is now
executable.
Maybe I am missing something, but I really don't think this is ready
for prime-time. We should effectively disable it all, and have people
think through it a lot more.
Linus
next prev parent reply other threads:[~2022-04-16 20:31 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-15 16:44 Song Liu
2022-04-15 16:44 ` [PATCH v4 bpf 1/4] vmalloc: replace VM_NO_HUGE_VMAP with VM_ALLOW_HUGE_VMAP Song Liu
2022-04-15 17:43 ` Rik van Riel
2022-04-15 16:44 ` [PATCH v4 bpf 2/4] page_alloc: use vmalloc_huge for large system hash Song Liu
2022-04-15 17:43 ` Rik van Riel
2022-04-25 7:07 ` Geert Uytterhoeven
2022-04-25 8:17 ` Linus Torvalds
2022-04-25 8:24 ` Geert Uytterhoeven
2022-04-15 16:44 ` [PATCH v4 bpf 3/4] module: introduce module_alloc_huge Song Liu
2022-04-15 18:06 ` Rik van Riel
2022-06-16 16:10 ` Dave Hansen
2022-04-15 16:44 ` [PATCH v4 bpf 4/4] bpf: use module_alloc_huge for bpf_prog_pack Song Liu
2022-04-15 19:05 ` [PATCH v4 bpf 0/4] vmalloc: bpf: introduce VM_ALLOW_HUGE_VMAP Luis Chamberlain
2022-04-16 1:34 ` Song Liu
2022-04-16 1:42 ` Luis Chamberlain
2022-04-16 1:43 ` Luis Chamberlain
2022-04-16 5:08 ` Christoph Hellwig
2022-04-16 19:55 ` Song Liu
2022-04-16 20:30 ` Linus Torvalds [this message]
2022-04-16 22:26 ` Song Liu
2022-04-18 10:06 ` Mike Rapoport
2022-04-19 0:44 ` Luis Chamberlain
2022-04-19 1:56 ` Edgecombe, Rick P
2022-04-19 5:36 ` Song Liu
2022-04-19 18:42 ` Mike Rapoport
2022-04-19 19:20 ` Linus Torvalds
2022-04-20 2:03 ` Alexei Starovoitov
2022-04-20 2:18 ` Linus Torvalds
2022-04-20 14:42 ` Song Liu
2022-04-20 18:28 ` Luis Chamberlain
2022-04-21 7:29 ` Song Liu
2022-04-21 3:25 ` Nicholas Piggin
2022-04-21 5:48 ` Linus Torvalds
2022-04-21 6:02 ` Linus Torvalds
2022-04-21 9:07 ` Nicholas Piggin
2022-04-21 8:57 ` Nicholas Piggin
2022-04-21 15:44 ` Linus Torvalds
2022-04-21 23:30 ` Nicholas Piggin
2022-04-22 0:49 ` Linus Torvalds
2022-04-22 1:51 ` Nicholas Piggin
2022-04-22 2:31 ` Linus Torvalds
2022-04-22 2:57 ` Nicholas Piggin
2022-04-21 15:47 ` Edgecombe, Rick P
2022-04-21 16:15 ` Linus Torvalds
2022-04-22 0:12 ` Nicholas Piggin
2022-04-22 2:29 ` Edgecombe, Rick P
2022-04-22 2:47 ` Linus Torvalds
2022-04-22 16:54 ` Edgecombe, Rick P
2022-04-22 3:08 ` Nicholas Piggin
2022-04-22 4:31 ` Nicholas Piggin
2022-04-22 17:10 ` Edgecombe, Rick P
2022-04-22 20:22 ` Edgecombe, Rick P
2022-04-22 3:33 ` Nicholas Piggin
2022-04-21 9:47 ` Nicholas Piggin
2022-04-19 21:24 ` Luis Chamberlain
2022-04-19 23:58 ` Edgecombe, Rick P
2022-04-20 7:58 ` Petr Mladek
2022-04-19 18:20 ` Mike Rapoport
2022-04-24 17:43 ` Linus Torvalds
2022-04-25 6:48 ` Song Liu
2022-04-21 3:19 ` Nicholas Piggin
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