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Subject: Re: [GIT PULL] x86/mm changes for v4.4
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
        Borislav Petkov <bp@alien8.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Denys Vlasenko <dvlasenk@redhat.com>
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On Tue, Nov 3, 2015 at 3:16 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> The new CONFIG_DEBUG_WX=y warning is marked default-y if CONFIG_DEBUG_RODATA=y is
> already eanbled, as a special exception, as these bugs are hard to notice and this
> check already found several live bugs.

So this seems to be not very useful.

  ...
  Freeing unused kernel memory: 1068K (ffffffff8bcc0000 -
ffffffff8bdcb000)
  Write protecting the kernel read-only data: 12288k
  Freeing unused kernel memory: 1944K (ffff88000b61a000 - ffff88000b800000)
  Freeing unused kernel memory: 1372K (ffff88000baa9000 - ffff88000bc00000)
  ------------[ cut here ]------------
  WARNING: CPU: 7 PID: 1 at arch/x86/mm/dump_pagetables.c:225
note_page+0x5dc/0x780()
  x86/mm: Found insecure W+X mapping at address
ffff88000005f000/0xffff88000005f000
  ...
  x86/mm: Checked W+X mappings: FAILED, 165660 W+X pages found.
  ...

because it doesn't seem to give you any idea where to look for the
issue. Those 165660 pages come out to 647MB. Odd number.

Is this *supposed* to come out clean?

                   Linus