On Wed, Nov 04, 2015 at 11:26:12AM -0800, Linus Torvalds wrote:
> On Tue, Nov 3, 2015 at 3:16 AM, Ingo Molnar <mi...@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?
FWIW I'm seeing this too.
[ 3.293503] x86/mm: Found insecure W+X mapping at address
ffff880000800000/0xffff880000800000
Looking further up the dmesg I see that range is..
[ 0.468368] ---[ Low Kernel Mapping ]---
[ 0.468381] 0xffff880000000000-0xffff880000800000 8M RW
GLB NX pte
[ 0.468391] 0xffff880000800000-0xffff880000900000 1M RW
GLB x pte
Linus, does that match your trace too ? The 2nd low kernel mapping?
Dave
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