Received-SPF: softfail (google.com: domain of transitioning linux-kernel-owner@vger.kernel.org does not designate 23.128.96.19 as permitted sender) client-ip=23.128.96.19;
MIME-Version: 1.0
References: <20220422060107.781512-1-npiggin@gmail.com> <20220422060107.781512-3-npiggin@gmail.com>
 <CAHk-=wgFoWLCV9aPHkHe1Mpu0XqxYWaPkKLpe_hcsTS_Vx3aRA@mail.gmail.com>
In-Reply-To: <CAHk-=wgFoWLCV9aPHkHe1Mpu0XqxYWaPkKLpe_hcsTS_Vx3aRA@mail.gmail.com>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 22 Apr 2022 11:41:38 -0700
Message-ID: <CAHk-=whao=iosX1s5Z4SF-ZGa-ebAukJoAdUJFk5SPwnofV+Vg@mail.gmail.com>
Subject: Re: [PATCH 2/2] Revert "vmalloc: replace VM_NO_HUGE_VMAP with VM_ALLOW_HUGE_VMAP"
To:     Nicholas Piggin <npiggin@gmail.com>
Cc:     Paul Menzel <pmenzel@molgen.mpg.de>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Song Liu <songliubraving@fb.com>,
        "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>
Content-Type: multipart/mixed; boundary="000000000000a114e105dd429420"
Precedence: bulk

--000000000000a114e105dd429420
Content-Type: text/plain; charset="UTF-8"

On Fri, Apr 22, 2022 at 10:08 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> Just opt-in with the mappings that matter.

Actually, we could automatically opt-in a few common cases that we
know are fundamentally ok, because they already can't play protection
games.

In particular, kvmalloc().

So I think something like this patch - along with Song's patch to
enable it for alloc_large_system_hash() - would be fairly safe, and
avoid any nasty cases.

And probably catch quite a lot of the cases that matter that can grow large.

               Linus

--000000000000a114e105dd429420
Content-Type: text/x-patch; charset="US-ASCII"; name="patch.diff"
Content-Disposition: attachment; filename="patch.diff"
Content-Transfer-Encoding: base64
Content-ID: <f_l2ary56k0>
X-Attachment-Id: f_l2ary56k0
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=
--000000000000a114e105dd429420--